Canadian Environmental Protection Act, 1999
Annual Report to Parliament for April 2020 to March 2021:
chapter 7

On this page

• 7. Report on research
  • 7.1 Chemical substances
    • 7.1.1 Environment and Climate Change Canada research
    • 7.1.2 Health Canada Research
  • 7.2 Air pollutants and greenhouse gases
    • 7.2.1 ECCC Research
    • 7.2.2 Health Canada research
  • 7.3 Water quality
    • 7.3.1 ECCC research

7. Report on research

ECCC and HC conduct a wide range of research to help inform assessment and management of the risks associated with various substances to human health or the environment. This research is often done in collaboration with scientists in other agencies and universities across Canada and the world. This section provides highlights of the research published in 2020-2021.

7.1 Chemical substances

Research on chemical substances is designed primarily to:

• fill data gaps in risk assessment and risk management
• develop novel methods and approaches to improve priority setting, support risk assessment and work towards the goal of reducing animal testing
• evaluate the fate and the impact of toxic substances, complex environmental mixtures, and other substances of concern on the environment and human health
• determine the extent of ecological and human health exposure to contaminants
• investigate the toxicity of chemicals, including effects on endocrine systems
• investigate the health effects of chemicals on human health

In addition, HC undertakes research to support the development of regulations, guidelines and air quality objectives with the goal of reducing population exposure to pollutants and improving human health.

During 2020-2021, research on chemicals was carried out by both departments under a number of programs, including the Chemicals Management Plan (CMP), the Northern Contaminants Program (NCP), the Strategic Technology Applications of Genomics in the Environment Program, Genome Canada and the Great Lakes Protection Initiative.

7.1.1 Environment and Climate Change Canada research

In 2020-2021, work on 19 new CMP research projects initiated in 2019-2020 continued, but at a slower pace than expected due to the COVID-19 pandemic and related suspension of laboratory and fieldwork for the entire year. Some of the latter work was able to progress for those research projects conducted in partnership with universities that only experienced short shutdown periods. It is worth noting that significant progress was made for all research projects in terms of data analysis and publication of manuscripts. Thirty-five papers related to chemicals in the atmosphere were published by ECCC scientists in 2020-2021, with references to a selection of these articles provided below as examples.

7.1.1.1 Chemicals in the atmosphere

• Persistent organic pollutants (POPs), organic flame retardants and other priority substances

  Focus of research: Long-term trends on Arctic concentrations of POPs and other chemicals of concern, indoor and outdoor concentrations of flame retardants and other chemicals of concern and potential for exposure.

  Results: In the Arctic, while some POPs showed declining trends at all monitoring sites, others were stable, increasing, or showed different trends at different locations. Phthalate concentrations in air are linked to both primary sources such as urban activity and traffic, and to secondary sources such as volatilization from water bodies. Landfill air was found to be a potential source of exposure to organic flame retardants. Liquid crystal monomers (LCMs) used in television and smartphone displays give off particles that were found to be more persistent in air than expected and whose oxidation produces many transformation products.

  Publications: Wong, F., Hung, H., Dryfhout-Clark, H., Aas, W., Bohlin-Nizzetto, P., Breivik, K., Mastromonaco, M.N., Lundén, E.B., Ólafsdóttir, K., Sigurðsson, Á., Vorkamp, K., Bossi, R., Skov, H., Hakola, H., Barresi, E., Sverko, E., Fellin, P., Li, H., Vlasenko, A., Zapevalov, M., Samsonov, D., Wilson, S. 2021. Time trends of persistent organic pollutants (POPs) and Chemicals of Emerging Arctic Concern (CEAC) in Arctic air from 25 years of monitoring. Science of the Total Environment, 775, art. no. 145109, DOI: 10.1016/j.scitotenv.2021.145109

  Vasiljevic, T., Su, K., Harner, T. 2020. A first look at atmospheric concentrations and temporal trends of phthalates in distinct urban sectors of the Greater Toronto Area. Atmospheric Pollution Research, Vol. 12, Issue 2, pp 173-182, DOI: 10.1016/j.apr.2020.10.019

  Navaranjan, G., Diamond, M.L., Harris, S.A., Jantunen, L.M., Bernstein, S., Scott, J.A., Takaro, T.K., Dai, R., Lefebvre, D.L., Azad, M.B., Becker, A.B., Mandhane, P.J., Moraes, T.J., Simons, E., Turvey, S.E., Sears, M.R., Subbarao, P., Brook, J.R. 2021. Early life exposure to phthalates and the development of childhood asthma among Canadian children. Environmental Research, 197, art. no. 110981, DOI: 10.1016/j.envres.2021.110981

  Kerric, A., Okeme, J., Jantunen, L., Giroux, J.-F., Diamond, M.L., Verreault, J. 2021. Spatial and temporal variations of halogenated flame retardants and organophosphate esters in landfill air: Potential linkages with gull exposure. Environ. Pollut., 271, art. no. 116396, DOI: 10.1016/j.envpol.2020.116396

  Liu, Q., Liggio, J., Wentzell, J., Lee, P., Li, K., Li, S.-M. 2020. Atmospheric OH Oxidation Chemistry of Particulate Liquid Crystal Monomers: An Emerging Persistent Organic Pollutant in Air. Environmental Science and Technology Letters, 7 (9), pp. 646-652. DOI: 10.1021/acs.estlett.0c00447.

• Microplastics and other man-made particles

  Focus of research: Measurement of microplastics and other man-made particles in the Canadian environment.

  Results: Microplastics or other anthropogenic particles were found in 85-90% of Arctic samples analyzed, highlighting the presence of microplastics across the eastern Canadian Arctic, in multiple media, and offering evidence of long-range transport via ocean and atmospheric currents. Denim fabrics were found to be a major contributor.

  Publications: Huntington, A., Corcoran, P.L., Jantunen, L., Thaysen, C., Bernstein, S., Stern, G.A., Rochman, C.M. 2020. A first assessment of microplastics and other anthropogenic particles in Hudson Bay and the surrounding eastern Canadian Arctic waters of Nunavut. Facets, 5 (1), pp. 432-454. DOI: 10.1139/FACETS-2019-0042.

  Athey, S.N., Adams, J.K., Erdle, L.M., Jantunen, L.M., Helm, P.A., Finkelstein, S.A., Diamond, M.L. 2020. The Widespread Environmental Footprint of Indigo Denim Microfibers from Blue Jeans. Environmental Science & Technology Letters 2020 7 (11), 840-847, DOI: 10.1021/acs.estlett.0c00498.

• Polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic compounds (PACs) in Canada

  Focus of research: Long-term trends and sources of PAHs and PACs in Canada.

  Results: PAHs in the Canadian Great Lakes Basin atmosphere significantly decreased between 1997 and 2017, as anthropogenic emissions declined. Tailings ponds of Athabasca oil sands operations were found to be a source of fugitive emissions of PACs and specific activities within oil sands operations were identified as potential sources of PACs.

  Publications: Li, W., Park, R., Alexandrou, N., Dryfhout-Clark, H., Brice, K., Hung, H. 2021. Multi-year analyses reveal different trends, sources, and implications for source-related human health risks of atmospheric polycyclic aromatic hydrocarbons in the Canadian Great Lakes basin. Environ. Sci. Technol., 55 (4), pp. 2254-2264. DOI: 10.1021/acs.est.0c07079.

  Moradi, M., You, Y., Hung, H., Li, J., Park, R., Alexandrou, N., Moussa, S.G., Jantunen, L., Robitaille, R., Staebler, R.M. 2020. Fugitive emissions of polycyclic aromatic compounds from an oil sands tailings pond based on fugacity and inverse dispersion flux calculations. Environ. Pollut., Vol. 269, 116115, https://doi.org/10.1016/j.envpol.2020.116115.

  Wnorowski, A., Aklilu, Y.-A., Harner, T., Schuster, J., Charland, J.-P. 2021. Polycyclic aromatic compounds in ambient air in the surface minable area of Athabasca oil sands in Alberta (Canada). Atmospheric Environment, 244, art. no. 117897, DOI: 10.1016/j.atmosenv.2020.117897

• Review of Polycyclic Aromatic Compounds (PACs) in Canadian environments

  Focus of research: A State of Knowledge report for PACs with focus on the Canadian environment

  Results: A state of knowledge report on PACs in the Canadian environment was published as a Special Issue in the Environmental Pollution journal. Scientists from the Canadian government and academia authored the Special Issue’s seven main papers. Five papers follow the environmental chain of events from emissions and releases to effects on wildlife, with additional papers examining the challenges of ecological risk assessment and the links between PACs and global change. Wildfire emissions were found to be by far the largest source of PACs in the Canadian atmosphere, followed by non-industrial sources (such as, residential firewood burning and mobile sources), and industrial sources. Significant PAC releases result from exploitation of fossil fuels containing naturally-derived PACs. Major cities within the Great Lakes watershed, act as diffuse sources of PACs, and result in coronas of contamination emanating from urban centres. A review of long-term trends in PAC concentrations in the atmosphere found that except near industries that had reduced emissions, trends were modest or negligible. The results also suggest that motor vehicles are a larger source than currently reported in national inventories. Considerable knowledge gaps limit current understanding of PAC sinks, environmental transformations and transboundary flows, as well as ecological impacts in Canada. In general, PAC concentrations in Canadian wildlife tissue were below guidelines.

  Publications: Galarneau, E. 2021. Editorial to “Polycyclic aromatic compounds (PACs) in the Canadian environment: overview of results and knowledge gaps from the special issue”. Environmental pollution. 285. 117607.

  Wallace, S.J., de Solla, S.R., Head, J.A., Hodson, P.V., Parrott, J.L., Thomas, P.J., Berthiaume, A., Langlois, V.S. 2020. Polycyclic aromatic compounds (PACs) in the Canadian environment: exposure and effects on wildlife. Environmental Pollution. 265:114863. https://doi.org/10.1016/j.envpol.2020.114863

  Hodson, P.V., Wallace, S.J., de Solla, S.R., Head, S.J., Hepditch, S.L.J., Parrott, J.L., Thomas, P.J., Berthiaume, A., Langlois, V.S. 2020. Polycyclic aromatic compounds (PACs) in the Canadian environment: the challenges of ecological risk assessments. Environmental Pollution. 265:115165.

  Ahad, J.M.E., Macdonald, R.W., Parrott, J.L., Yang, Z., Zhang, Y., Siddique, T., Kuznetsova, A., Rauert, C., Galarneau, E., Studabaker, W.B., Evans, M., McMaster, M.E., Shang, D. 2020. Polycyclic aromatic compounds (PACs) in the Canadian environment: a review of sampling techniques, strategies and instrumentation. Environmental Pollution. 266:114988.

  Berthiaume, A., Galarneau, E., Marson, G. 2020. Polycyclic aromatic compounds (PACs) in the Canadian environment: sources and emissions. Environmental Pollution Vol. 269, 116008, DOI: 10.1016/j.envpol.2020.116008

  Tevlin, A., Galarneau, E., Zhang, T., Hung, H. 2021. Polycyclic aromatic compounds (PACs) in the Canadian environment: ambient air and deposition. Environmental Pollution, 271. 116232

  Muir, D.C.G., Galarneau, E. 2021. Polycyclic aromatic compounds (PACs) in the Canadian environment: links to global change. Environmental Pollution. 273: 116425.

  Marvin, C.H., Berthiaume, A., Burniston, D.A., Chibwe, L., Dove, A., Evans, M., Hewitt, L.M., Hodson, P.V., Muir, D.C.G., Parrott, J., Thomas, P.J., Tomy, G.T. 2021. Polycyclic aromatic compounds in the Canadian Environment: aquatic and terrestrial environments. Environmental Pollution 285 (2021) 117442.

7.1.1.2 Impact of chemicals on wildlife and fish

• Review of biological effects of wildlife exposed to chemicals of emerging Arctic concern

  Focus of research: A review of the state-of-the-knowledge regarding chemicals of emerging Arctic concern (CEACs) and the general lack of information on the potential biological adverse effects on Arctic wildlife.

  Results: Recent advances in environmental analytical chemistry have identified the presence of a large number of CEACs being transported long range to the region. There has been very limited temporal monitoring of CEACs and it is therefore unknown whether they are of increasing or decreasing concern. Likewise, information on potential biological adverse effects from CEACs on Arctic wildlife is lacking compared with legacy persistent organic pollutants (POPs) found at levels associated with health effects in marine mammals. Hence, there is a need to monitor CEACs along with POPs to support risk and regulatory CEAC assessments.

  Publication: Sonne, C., Dietz, R., Jenssen, B.M., Lam, S.S., Letcher, R.J. 2021. Emerging contaminants and biological effects in Arctic wildlife. Trends in Ecology and Evolution - Opinion, Volume 26, 421-429, DOI.org/10.1016/j.tree.2021.01.007.

• Comparative review of the distribution and burden of contaminants in the body of polar bears

  Focus of research: Historical (or legacy) contaminants, such as metals and persistent organic pollutants (POPs; such as polychlorinated biphenyls) have been measured in circumpolar subpopulations of polar bears, especially from Hudson Bay, East Greenland, and Svalbard, but substantially less is currently known about new and/or emerging contaminants such as polychlorinated naphthalenes, current-use pesticides, organotins, and polycyclic aromatic compounds (PACs).

  Results: The polar bear (Ursus maritimus) is an apex Arctic predator that accumulates high levels of bioaccumulative POPs and mercury (Hg), but there is currently no comprehensive profiling of the present knowledge on contaminants in tissue and body compartments in polar bears. Based on current literature reports and data, and including archived museum samples (as far back as the 1300s) and up to 2018, results showed that (1) the kidneys are one of the most important tissue depots of contaminants in polar bears; (2) there is a critical lack of data concerning the presence of metals of concern, other than Hg; and (3) there is currently no data available on the concentrations of many newer and emerging contaminants, such as polycyclic aromatic compounds (PACs), which is especially relevant given the increasing oil and gas development in regions, such as in the Beaufort Sea, Canada.

  Publication: Dominique, M., Letcher, R.J., Rutter, A., Langlois, V.S. 2020. Comparative review of the distribution and burden of contaminants in the body of polar bears. Environmental Sciences and Pollution Research 27, 2020, 32456–32466, DOI.org/10.1007/s11356-020-09193-2.

• Influence of diet specialization on persistent organic pollutants in Icelandic killer whales

  Focus of research: The focus of this study was on the inter-individual variation in prey specialization in Icelandic killer whales (Orcinus orca) and intra-population variation in exposure to persistent organic pollutants.

  Results: Polychlorinated biphenyl (PCB) concentrations in blubber were >300-fold higher in the most contaminated individual killer whales relative to the least contaminated, ranging from 1.3 to 428.6 mg/kg lipid weight. Mean PCB concentrations were 6-to-9-fold greater in individuals with a mixed diet including marine mammals than in fish specialist individuals, whereas males showed PCB concentrations 4-fold higher than females. Given PCBs have been identified as potentially impacting killer whale population growth, and levels in mixed feeders specifically exceeded known thresholds, the ecology of individuals must be recognized to accurately forecast how contaminants may threaten the long-term persistence of the world’s ultimate marine predator.

  Publication: Remili, A., Letcher, R.J., Samarra, F.I.P., Dietz, R., Sonne, C., Desforges, J.P., Vikingsson, G., Blair, D., McKinney, M.A. 2021. Individual prey specialization drives PCBs in Icelandic killer whales. Environmental Science and Technology Volume 55, 2021, 4923-4931, DOI.org/10.1021/acs.est.0c08563.

• Mercury in gull eggs and fish under a warming climate

  Focus of research: Understanding changes in environmental mercury concentrations is important for assessing the risk to human and wildlife populations from this potent toxicant. Herring gull (Larus argentatus) eggs were used to evaluate temporal changes in total mercury availability from 2 locations on Great Slave Lake, Northwest Territories, Canada.

  Results: Temporal trends in mercury in herring gull (Larus argentatus) eggs from Great Slave Lake (GSL), Northwest Territories, Canada were evaluated. Although diet-adjusted mercury concentrations in eggs showed no long-term trend, consistent with the lack of trends in GSL fish, egg mercury concentrations were greater following years of lower lake levels and greater wildfire extent. Climate change may increase wildfire extent with impacts on Hg bioaccumulation in northern ecosystems. The study emphasizes the importance of ancillary datasets in elucidating Hg trends; such information will be critical for evaluating the effectiveness of Hg mitigation strategies implemented as part of the Minamata Convention.

  Publication: Hebert, C.E., Chételat, J., Beck, R., Dolgova S., Fordy K., Kirby P., Martin, P., Rabesca, M. 2021. Inter-annual variation of mercury in aquatic bird eggs and fish from a large subarctic lake under a warming climate. Science of the Total Environment, 2021, 766, 144614

• Priority perfluroalkyl substances in predatory birds: diet, biology and ecology factors

  Focus of research: Perfluoroalkyl substances (PFAS) are a large, diverse group of chemicals and several perfluoroalkyl acids (PFAAs) are known environmental contaminants. Wildlife exposure to PFAAs and precursors has been shown, but less is known regarding replacements such as shorter-chain PFAS. In the present study, exposure to a suite of PFAAs and associations with dietary, biological and ecological factors were investigated in populations of a sentinel apex species - the peregrine falcon (Falco peregrinus).

  Results: Peregrine nestling blood and sibling eggs were sampled in 2016 and 2018 from nests in rural and urban regions across the Laurentian Great Lakes Basin, Canada. Analytical results reveal that exposure to PFAAs in peregrine falcons is likely mediated by dietary factors such as foraging location and trophic position. Moreover, results suggest that compared to rural nestlings, urban nestlings may be more exposed to perfluorinated carboxylic acids (PFCAs) and prone to their potential physiological impacts. Findings highlight the importance of integrating dietary, biological and ecological factors when studying PFAS exposure in birds.

  Publication: Sun, J., Letcher, R.J., Eens, M., Covaci, A., Fernie, K.J. 2020. Perfluoroalkyl acids and sulfonamides and dietary, biological and ecological associations in peregrine falcons from the Laurentian Great Lakes Basin. Environmental Research volume 191, 2020, 110151, DOI.org/10.1016/j.envres.2020.110151.

• Assessing the lethal and sublethal toxicity of perfluorooctanoic acid (PFOA) to Hyalella azteca and Pimephales promelas.

  Focus of Research: PFOA, which is widely used in a variety of residential, commercial, and industrial products, belongs to the broader chemical class of perfluoroalkyl substances (PFAS). It has been measured in the Canadian aquatic environment and is known to be extremely environmentally persistent, but little information exists on its toxicity to aquatic organisms. The objective of this study was to assess the toxicity of PFOA to two sensitive and important freshwater species relevant to the Canadian environment: a small, shrimp-like crustacean (amphipod, Hyalella azteca) and a fish (fathead minnow, Pimephales promelas).

  Results: Exposure to PFOA decreased survival, growth, and reproduction in amphipods, and caused abnormal swimming behaviour in fathead minnow larvae. Amphipod growth and reproduction were the most sensitive endpoints tested. The toxic effects of PFOA observed in this study occurred at concentrations more than 75-fold higher than those that have been measured in Canadian freshwaters; however, due to its environmental persistence, more research is needed to determine if PFOA causes toxicity at lower concentrations after longer exposure periods.

  Publication: Bartlett, A.J., De Silva, A.O., Schissler, D.M., Hedges, A.M, Brown, L.R., Shires, K., Miller, J., Sullivan, C., Spencer, C., Parrott, J.L. 2021. Lethal and sublethal toxicity of perfluorooctanoic acid (PFOA) in chronic tests with Hyalella azteca and early-life stages with Pimephales promelas (fathead minnow). Ecotoxicology and Environmental Safety 207:111250.

• Toxicity of naphthalene sulfonic acids (NSAs) in aquatic organisms

  Focus of Research: Assessment of the aquatic toxicity of naphthalene sulfonic acids (NSAs), which are high production volume chemicals used primarily as additives in a wide range of industrial products.

  Results: The effects of NSAs, which are used extensively in industrial applications as dispersants in dyes, rubbers, and pesticides, and as anti-corrosive agents in coatings, gels, and sealants, were assessed in several invertebrates and fish. The organic carbon content of the sediment appears to have acted as a sink and reduced NSA toxicity by decreasing bioavailability to aquatic organisms. However, for one NSA (dinonylnaphthalene sulfonic acid), the Biota-Sediment Accumulation Factor indicated a potential biomagnification concern if this compound were to occur in the aquatic environment.

  Publications: Matten, K.J., Bartlett, A.J., Milani, D., Gillis, P.L., Parrott, J.L., Toito, J, Balakrisknan, V.K., Prosser, R.S. 2020. The influence of organic carbon on the toxicity of sediment-associated dinonylnaphthalene sulfonic acids to the benthic invertebrates Tubifex tubifex and Hyalella azteca. Environmental Pollution 267:115604 https://doi.org/10.1016/j.envpol.2020.115604

  Matten, K.J., Gillis, P.L., Milani, D. Parrott, J.L., Bartlett, A.J. Toito, J., Balakrishnan, V.K., Prosser, R.S. 2021. Bioaccumulation of sediment-associated dinonylnaphthalene sulfonates in the freshwater mussel Lampsilis siliquoidea and oligochaete Tubifex tubifex. Chemosphere 264:128391 https://doi.org/10.1016/j.chemosphere.2020.128391

• Determining the effects of bisphenol A (BPA) replacement alternatives in avian species

  Focus of research: Several screening studies using high-throughput approaches were conducted using primary avian hepatocytes and early-life stage chicken embryos as part of a prioritization effort to determine the effects of this priority chemical class. Cytotoxic and transcriptomic effects of 5 BPA replacement alternatives were determined and 1 early-life stage chicken embryo exposure evaluating two BPA alternatives was performed.

  Results: Many BPA replacement alternatives were more cytotoxic and disrupted more gene expression in avian cells than BPA. The effects were most pronounced in cells derived from chicken compared to a wild avian species, double-crested cormorant, for gene expression. However, cormorant cells were typically more sensitive to overt toxicity/cell death. Taken together, these studies indicate that additional research is required to characterize the toxic mechanisms of action of several substances proposed to be suitable replacements for BPA in commercial/industrial applications.

  Publications: Sharin, T., Williams, K.L., Chiu, S., Crump, D., O’Brien, J.M. 2021. Toxicity Screening of Bisphenol A Replacement Compounds: Cytotoxicity and mRNA Expression in Primary Hepatocytes of Chicken and Double-Crested Cormorant. Environ. Tox. Chem 40 (5): 1368-1378.

  Sharin, T., Gyasi, H., Williams, K., Crump, D., O'Brien, J.M. 2021. Effects of Two Bisphenol A Replacement Compounds, Bisphenol AF and 1,7-bis (4-Hydroxyphenylthio)-3,5-dioxaheptane, on Pipping Success, Development, and mRNA Expression Levels in Chicken Embryos. Ecotox. Environ Safety 215: 112140.

• Effects of neonicotinoid insecticides on non-target aquatic organisms

  Focus of research: The study assessed the effects of neonicotinoid insecticides on tadpole stress metrics to understand the sublethal effects of chronic exposure to these compounds on sensitive non-target vertebrates. Specifically, blood cell profiles, measures of oxidative stress and concentrations of a stress hormone, corticosterone were assessed.

  Results: Northern leopard frogs (Rana (Lithobates) pipiens) were found to show signs of mild stress based on blood cell profiles and some indication for oxidative damage when exposed to clothianidin (a neonicotinoid). Furthermore, thiamethoxam (also a neonicotinoid) altered some blood cell profiles, but neither clothianidin nor thiamethoxam affected corticosterone concentrations. These studies indicate that northern leopard frog tadpoles exposed to some neonicotinoids for prolonged periods have increased stress responses, but the implications on overall health are unclear.

  Publication: Gavel, M.J., Young, S.D., Dalton, R.L., Soos, C., McPhee, L., Forbes, M.R., Robinson, S.A. 2021. Effects of 2 pesticides on northern leopard frog (Lithobates pipiens) stress metrics: Blood cell profiles and corticosterone concentrations. Aquatic Toxicology 235:105820 DOI:10.1016/j.aquatox.2021.105820

• Evaluation of estrogenic and thyroid-disrupting activities of brominated organophosphate flame retardant

  Focus of research: The study assessed the effects of a new alternative phosphate flame retardant, the brominated organophosphate ester flame retardant, tris(tribomoneopentyl) phosphate (TTBrNP, CAS 19186-97-1). Canadian native frogs (wood frogs (Rana (Lithobates) sylvaticus) and northern leopard frogs (R. pipiens)) were used to determine if embryo or tadpole survival was affected after 96 hours of exposure or if the compound affected metamorphosis, growth, sexual differentiation or bioconcentrated in tadpole tissues after 30 days of exposure.

  Results: Acute 96-hour exposures did not affect embryo or tadpole survival for either species. There was also no sub-chronic effects after 30 days of exposure, where size, developmental stage and sex ratio did not differ compared to the control at any of the exposure concentrations. Tadpoles bioconcentrated TTBrNP, but the low bioconcentration factor suggested the compound is being biotransformed or has limited bioavailability. Hence, TTBrNP was found to have no overt detrimental effects on these 2 frog species.

  Publication: Robinson, S.A., Young, S.D., McFee, A., Brinovkar, C., De Silva, A.O. 2020. Ecotoxicity assessment and bioconcentration of a highly brominated organophosphate ester flame retardant in 2 amphibian species. Chemosphere 260: 127631 DOI:10.1016/j.chemosphere.2020.127631

• Priority perfluroalkyl substances: Uptake, bioaccumulation and toxic effects in terrestrial and marine birds

  Focus of research: The goal of this research was to characterize the exposure of raptors and tree swallows to high-priority perfluorinated compounds, and to determine the possible effects to the birds of these chemicals and to model chemical movements through the terrestrial food web.

  Results: Peregrine falcon chicks were sampled across urban and rural regions of the Canadian Great Lakes Basin (2016, 2018) to investigate possible relationships of thyroid hormones (THs), specifically free (F) and total (T) thyroxine (FT4; TT4) and triiodothyronine (FT3; TT3), and the expression of an immune-related microRNA biomarker (for example, miR-155), with the concentrations of 11 perfluoroalkyl acids (PFAAs). Five of the 18 measured PFAA homologues were repeatedly and positively related with measurements of thyroid activity in the nestling peregrines suggesting probable disruption of the thyroid system of the peregrine falcon nestlings. Multiple environmental and biological stressors, including PFAA-exposure, influenced thyroid activity and immune function in these nestlings. Further research is warranted to identify the mechanisms and additional impacts of PFAA-related thyroid and immune disruption on the growth, development, and health risks in developing birds.

  Publication: Sun J., Letcher, R.J., Waugh, C.A., Jaspers, V.L.B., Covaci, A,. Fernie, K.J. 2021. Influence of perfluoroalkyl acids and other parameters on circulating thyroid hormones and immune-related microRNA expression in free-ranging nestling peregrine falcons. Sci. Tot. Environ. https://doi.org/10.1016/j.scitotenv.2021.145346

• Priority Short Chain Chlorinated Paraffins and Wildlife: Toxic effects to predatory birds

  Focus of research: The goal of this research was to characterize the possible toxic effects of high-priority short chain chlorinated paraffins in birds.

  Results: Short chain chlorinated paraffins (SCCPs) are complex mixtures of polychlorinated n-alkanes, shown to bioaccumulate but with unknown effects in wild birds. Embryonic exposure to technical Chloroparaffin® (C_10-13, 55.5% Cl) at concentrations measured in wild bird eggs had sex-specific effects on uptake. SCCPs suppressed glandular total thyroxine (TT4) and reduced circulating triiodothyronine (TT3) in male hatchlings only when compared to control males, but had no effect on glandular TT3 or circulating TT4 in male or female kestrels. Both sexes experienced significant structural (histological) changes indicative of thyroid gland activation. Because changes in thyroid function were evident at concentrations measured in wild bird eggs, similar changes may occur in wild nestlings.

  Publication: Fernie K.J., Karoun-Renier, N.K., Letcher, R.J., SL Schultz, S.L., Palace, V., Peters, L., Henry, P.F.P. 2020. Endocrine and physiological responses of hatchling American kestrels (Falco sparverius) following embryonic exposure to technical short chain chlorinated paraffins (C_10-13, 55.5% Cl). Environ. International. https://doi.org/10.1016/j.envres.2020.106087

• Elimination and toxicity of PCBs to turtles

  Focus of research: Polychlorinated biphenyls (PCBs) remain the most abundant organic contaminant in most wildlife. This study examined the effects of PCBs in an understudied taxonomic group: freshwater turtles.

  Results: Juvenile snapping turtles were exposed to PCBs (Aroclor 1254) through diet. Accumulation was relatively low, but a 1.8-fold increase in hepatic expression of cytochrome P450 1a was observed at the highest dosage (12.7 µg/g; range 0–12.7 µg/g), which corresponded to egg burdens that have been observed in the Great Lakes.

  Publication: Colson, T.-L.L., de Solla, S.R., Langlois, V.S. 2021. Bioaccumulation and physiological responses of the turtle Chelydra serpentina exposed to polychlorinated biphenyls during early life stages. Chemosphere, 263, art. no. 128146.

• Accumulation and toxicity of substituted phenylamine antioxidants to turtles

  Focus of research: Exposure of substituted phenylamine antioxidants (such as, N-phenyl-1-naphthylamine; PNA) is not well known in aquatic amniotes. This study exampled molecular response of turtles to exposure of PNA through diet.

  Results: Juvenile snapping turtles were chronically exposed to PNA through diet. At the highest exposure (µg/g), cytochrome P450 1a was induced but cytochrome P450 2b was inhibited, indicating alteration in genes associated with metabolism and elimination.

  Publication: Colson, T.-L.L., de Solla, S.R., Balakrishnan, V.K., Toito, J., Langlois, V.S. 2020. N-phenyl-1-naphthylamine (PNA) Accumulates in Snapping Turtle (Chelydra serpentina) Liver Activating the Detoxification Pathway. Bulletin of Environmental Contamination and Toxicology, 105 (6), pp. 813-818.

• Effects of calcium dinonylnaphthalenesulfonate to amphibians

  Focus of research: This study estimated the toxicity of naphthalene sulfonic acids (calcium dinonylnaphthalenesulfonate [CaDNS]), to Western clawed frogs (Silurana tropicalis) and the mechanisms of toxicity of CaDNS using targeted gene expression and metabolomics.

  Results: Frog embryos were exposed to water overlying sand spiked with a range of concentrations of CaDNS (17–1393 μg/g) over a 72-hour period. Although not acutely toxic until 672 μg/g CaDNS in the sand (14 ng/mL CaDNS in the water), an overall decrease in the mRNA of genes in the glutathione redox cycle was observed; these changes in mRNA were reflected in the metabolic responses (decreases in the glutathione and glutathione disulfide metabolite concentrations). In addition, transcript levels of genes involved in antioxidant capacity and essential amino acid metabolites decreased significantly in embryos exposed to low levels of CaDNS.

  Publication: Wallace, S.J., Leclerc, A.J.A., Prosser, R., de Solla, S.R., Balakrishnan, V., Langlois, V.S. 2020. Sub-lethal effects of calcium dinonylnaphthalenesulfonate on Western clawed frog embryos. Comparative Biochemistry and Physiology - Part D: Genomics and Proteomics, 34, art. no. 100658

• Environmental fate, effects and bioaccumulation of priority nanomaterials in soil

  Focus of research: The effect of metal nanomaterials (nano copper (II) oxide and nano cerium (IV) oxide) on indigenous microorganisms in agricultural soil were examined, with and without biosolid amendment.

  Results: This project determined the conditions and concentrations at which selected metal nanomaterials exert adverse effects on different aspects of the soil ecosystem: soil microbial growth, activity and diversity. The research demonstrated the utility of alternate metrics to measure bioavailability and toxicity.

  Publications: Samarajeewa, A.D., Velicogna, J.R., Schwertfeger, D.M., Princz, J.I,, Subasinghe, R.M,, Scroggins, R.P., Beaudette, L.A. 2021. Ecotoxicological effects of copper oxide nanoparticles (nCuO) on the soil microbial community in a biosolids-amended soil. Science of the Total Environment 763: 143037.

  Abdulsada, Z., Kibbee, R., Ormeci, B., DeRosa, M., Princz, J. 2021. Impact of anaerobically digested silver and copper oxide nanoparticles in biosolids on soil characteristics and bacterial community. Chemosphere 263:128173.

• Toxicity of rare earth elements in rainbow trout and hydra

  Focus of research: To determine the toxicity and the mechanism of action of rare earth elements.

  Results: The toxicity and mode of action for over 10 rare earth elements were examined in rainbow trout and hydra. The lethal toxicity could be predicted by the electronegativity and ionic radius in fish and hydra. The mode of action studies revealed that rare earth elements could damage (denature) proteins, alter bone formation and damage DNA at concentrations 200 times below the acute toxicity values.

  Publications: Hanana, H., Taranu, Z.E., Turcotte, P., Gagnon, C., Kowalczyk, J., Gagné, F. 2020. Evaluation of general stress, detoxification pathways, and genotoxicity in rainbow trout exposed to rare earth elements dysprosium and lutetium. Ecotoxicology and Environmental Safety, 2021, 208, 111588

  Hanana, H., Taranu, Z.E., Turcotte, P., Kowalczyk, J., Gagné, F. 2021. Sublethal effects of terbium and praseodymium in juvenile rainbow trout. Science of the Total Environment, 2021, 777, 146042.

7.1.2 Health Canada Research

HC funded 27 CMP research projects in 2020-2021. These projects address departmental and international priorities and cover a number of subjects such as characterization of nanomaterials, toxicological response to nanomaterials, carcinogenic potential of chemicals, genetic toxicity assessment, effects of chemicals on human health, and hazard characterization.

7.1.2.1 Methods

• Derivation of biomonitoring equivalents for organics and inorganics for interpreting biomonitoring data

  Focus of research: Biomonitoring can provide valuable data on the presence of trace levels of chemicals in human blood, urine or breast milk; however, it is not enough to establish the potential risk to human health. A biomonitoring equivalent (BE) is the concentration of a chemical in human tissue or fluid that corresponds to an allowable exposure guidance value, such as a reference dose (RfD) or tolerable daily intake (TDI), that is considered safe. The objective is to derive BEs for rare earth metals to interpret biomonitoring data in support of the chemical risk assessments.

  Results: BEs for bismuth and titanium were developed and published. In addition, a database was produced to help analyze different biomonitoring values from various health agencies.

  Publications: Poddalgoda, D., Hays, S.M., Nong, A. 2020. Derivation of biomonitoring equivalents (BE values) for bismuth. Regul. Toxicol. Pharmacol. 2020 Jul;114:104672. 10.1016/j.yrtph.2020.104672

  Ramoju, S., Andersen, M.E., Nong, A., Karyakina, N., Shilnikova, N., Krishnan, K., Krewski, D. 2020. Derivation of whole blood biomonitoring equivalents for titanium for the interpretation of biomonitoring data. Regul. Toxicol. Pharmacol. 2020 Jul;114:104671. 10.1016/j.yrtph.2020.104671

• Development and validation of rapid methods to assess endocrine toxicity

  Focus of research: There are growing concerns that exposures to commercial chemicals cause harm by interfering with the hormonal control of growth and development of the brain, reproductive tract and lead to metabolic and stress-related problems. Developing rapid methods to identify chemicals posing these hazards is a critical need for safety assessment. This project will (1) develop rapid methods to detect chemical toxicity to thyroid hormone signalling and (2) identify, characterize and develop assays for the enzymes that are inhibited by some organophosphate flame retardants (OPFR) leading to toxicity to the ovary and adrenal gland.

  Results: Innovative methods are used to identify proteins that react with the flame retardant molecules. Early results show that these are enzymes involved in cholesterol metabolism. Assays for these enzymes are currently being developed and will be used to compare the potency across all phosphate flame retardants used in Canada. This project contributes to a global initiative to characterize the molecular targets influenced by hazardous substances and to develop validated, high throughput methods to rapidly screen chemicals for toxicity.

  Publication: Allais, A., Albert, O., Lefèvre, P.L.C., Wade, M.G., Hales, B.F., Robaire, B. 2020. In Utero and Lactational Exposure to Flame Retardants Disrupts Rat Ovarian Follicular Development and Advances Puberty. Toxicol Sci Jun 1;175(2):197-209. DOI: 10.1093/toxsci/kfaa044.

• Developing in vitro screening methods for metabolic disruptors in adipocytes

  Focus of research: There is increased concern that chemicals can act as endocrine disruptors and contribute to the development of endocrine cancers, as well as metabolic disease. The adipose tissue is an endocrine organ responsible for the energy homeostasis of the organism. This project employs cell-based models to investigate chemical effects on adipose mass and functional changes in the adipocyte that may indicate broader metabolic effects.

  Results: To date, there is limited information and no high content or validated screening method for the functionality of the fat cells exposed to chemicals. This project is working to develop a screening method, which can both identify substances that drive fat cell formation and determine if they contribute to metabolic disease.

  Publications: Peshdary, V., Styles, G., Rigden, M., Caldwell, D., Kawata, A., Sorisky, A., Atlas, E. 2020. Exposure to Low Doses of Dechlorane Plus Promotes Adipose Tissue Dysfunction and Glucose Intolerance in Male Mice. Endocrinology. 2020 Aug 1;161(8):bqaa096. DOI: 10.1210/endocr/bqaa096.

  Peshdary, V., Hobbs, C., Maynorc, T., Shepard, K., Gagné, R., Williams, A., Kuo, B., Chepelev, N., Recio, L., Yauk, C., Atlas, E. Transcriptomic pathway and benchmark dose analysis of Bisphenol A, Bisphenol S, Bisphenol F, and 3,3',5,5'-Tetrabromobisphenol A in H9 human embryonic stem cells. Toxicol In Vitro 2021 Apr;72:105097. DOI: 10.1016/j.tiv.2021.105097

• GeneTox21 - An integrated, high-throughput (HT) platform for in vitro genetic toxicity assessment of new and existing chemicals

  Focus of research: Chemical screening programs routinely assess a chemical’s ability to damage genetic material (for example, genetic toxicity). Traditional assessment tools (for example, bioassays) are laborious and not conducive to high-throughput (HT), high-content chemical screening using tools that employ cultured cells (for example, in vitro bioassays). This project is developing a NAMs (New Approach Methodologies)-based platform, comprised of high(er) throughput (HT) in vitro bioassays, for effective and efficient assessment of chemically-induced genetic toxicity. The NAMs-based platform, which is called GeneTox21, will be internationally promoted to encourage its adoption for robust genetic toxicity assessment of new and existing substances.

  Results: In-house standardised operating procedures (SOPs) have been established for efficient and effective assessment of genetic mutations, DNA breaks, and chromosome abnormalities. These SOPs are being employed to assess the genetic toxicity of a carefully-chosen set of reference compounds, as well as numerous data-poor substances prioritized for regulatory evaluation. Work includes advancement towards validation of the MutaMouse FE cell in vitro mutagenicity assay, and the development of an in vitro mutagenicity assay based on cultured murine liver cells. Additional work developed a beta version of a bioinformatics tool to integrate, visualise and interpret complex, multi-assay genetic toxicity assessment data. The tool is called IATGA - Integrated Analysis Tool for Genotoxicity Assessment.

  Publications: Höltz-Armstrong, L., Naevisdal, A., Cox, J.A., Long, A.S., Cheplev, N.L., Phillips, D.H., White, P.A. and Arlt, V.M. 2020. In vitro mutagenicity of selected environmental chemicals and their metabolites in MutaMouse FE lung epithelial cells. Mutagenesis 35:453-463.

  Madia, F., Kirkland, D., Morita, T., White, P.A., Asturiol, D., Corvi, R. 2020. EURL ECVAM Genotoxicity and Carcinogenicity Database of Substances Eliciting Negative Results in the Ames Test: Construction of the Database. Mutation Research 854-855:503199.

• Assessing somatic and germ cell mutations using the OECD’s transgenic rodent test guideline TG 488 and the MutaMouse model

  Focus of research: The objective is to harmonize the experimental design to identify somatic and germline mutations at a single time point. This integrated approach will significantly reduce the number of animals that are needed for the testing of chemicals for regulatory purposes.

  Results: Data generated by this project resulted in an update of the recommended experimental design for germ cells in an Organisation for Economic Cooperation and Development (OECD) test guideline that is routinely used to assess the ability of chemicals to induce mutations (that is, changes in the sequence of the DNA). Ongoing work is contributing to identify a common sampling time for somatic tissues and germ cells.

  Publication: Marchetti, F., Zhou, G., LeBlanc, D., White, P,A,, Williams, A., Yauk, C.L., Douglas, G.R. 2021. The 28+28 day design is an effective sampling time for analyzing mutant frequencies in rapidly proliferating tissues of MutaMouse animals. Archives of Toxicology, 95:1103-1116. Epub: January 28, 2021.

• Development and application of novel tools and new approach methodologies (NAM)

  Focus of research: HC and ECCC continue to increase efforts in support of the progressive advancement of risk science through the exploration, development and application of computational tools and NAM to effectively leverage and integrate existing and emerging data.

  Results: In 2020-2021, the focus was on building risk-based science approaches and illustrative examples for the application of NAM, including predictive models and in vitro high-throughput screening assays, to rapidly and effectively identify and assess the potential for hazard and/or risk in support of assessment modernization. This and ongoing work is being done through strong partnerships and collaborations between the research and regulatory communities within the Government of Canada and internationally to ensure alignment and increase global confidence in application.

  Publications: Rowan-Carroll, A., Reardon, A., Leingartner, K., Gagné, R., Williams, A., Meier, M.J., Kuo, B., Bourdon-Lacombe, J., Moffat, I., Carrier, R., Nong, A., Lorusso, L., Ferguson, S.S., Atlas, E., Yauk, C. 2021. High-Throughput Transcriptomic Analysis of Human Primary Hepatocyte Spheroids Exposed to Per- and Polyfluoroalkyl Substances as a Platform for Relative Potency Characterization. Toxicol Sci. 2021 May 27;181(2):199-214. DOI:10.1093/toxsci/kfab039.

  Yang, C., Rathman, J.F., Magdziarz, T., Mostrag, A., Kulkarni, S., Barton-Maclaren, TS. 2021. Do Similar Structures Have Similar No Observed Adverse Effect Level (NOAEL) Values? Exploring Chemoinformatics Approaches for Estimating NOAEL Bounds and Uncertainties. Chem Res Toxicol. 2021 Feb 15;34(2):616-633. DOI: 10.1021/acs.chemrestox.0c00429.

• Validation of the zebrafish (Brachydanio rerio) model as a whole organism NAM for risk assessment

  Focus of Research: Within the context of global efforts to meet the 3 Rs (refinement, reduction and replacement) of animal use in chemical risk assessment, HC is developing the zebrafish embryo model as a NAM whole organism model to transition from animal to non-animal models. Specifically, Health Canada is researching the utility of the zebrafish embryo test for assessment of chemicals for endocrine disruption and the zebrafish larval test as an alternative whole organism model to the 28-day rodent assay for assessments of general toxicity.

  Results: Building on previous research, the toxicity profiles of 20 compounds were compared using the General and Behavioral Toxicity (GBT) assay and the Zebrafish Embryo Toxicity (ZET) assay. The results show partially overlapping toxicity profiles along with unique information provided by each assay. It appears from this work that these two assays applied together can strengthen the use of zebrafish embryos/larvae as standard toxicity testing models.

  Publication: Achenbach, J.C., Leggiadro, C., Sperker, S., Woodland, C., Ellis, L.D. 2020. Comparison of the Zebrafish Embryo Toxicity Assay and the General and Behavioural Embryo Toxicity Assay and New Approach Methods for Chemical Screening. Toxics 2020, 8, 126; DOI:10.3390/toxics8040126

• Development of an integrated approach for the testing and assessment of chemical non-genotoxic carcinogens

  Focus of research: There is no unifying mechanism of action for the induction of cancers by non-genotoxic carcinogens (NGTxC). The NGTxCs are chemicals that do not have the inherent capacity at creating DNA damage. There are no validated OECD assays for the identification of NGTxC. OECD has created an expert working group to overcome this internationally recognized gap.

  Results: The expert working group is developing an integrated approach to the testing and assessment (IATA) of NGTxC. This involves a strategy to organize existing and new toxicological information using adverse outcome pathway concepts and common hallmarks of cancers, performing literature searches and evaluating chemical carcinogenicity assays, and identifying those that can be used in the IATA to reduce uncertainties in predicting the carcinogenicity of NGTxC thereby reducing public health hazards.

  Publication: Jacobs, M.N., Colacci, A., Corvi, R., Vaccari, M., Aguila, M.C., Corvaro, M., Delrue, N., Desaulniers, D., Ertych, N., Jacobs, A., Luijten, M., Madia, F., Nishikawa, A., Ogawa, K., Ohmori, K., Paparella, M., Kumar Sharma, A., Vasseur, P. 2020. Chemical carcinogen safety testing: OECD expert group international consensus on the development of an integrated approach for the testing and assessment of chemical non-genotoxic carcinogens. Archives of Toxicology, 94:2899-2923. DOI:10.1007/s00204-020-02784-5.

• Non-targeted screening analysis approaches for identifying emerging metabolites and chemicals in human fluids

  Focus of research: There is a gap between pre-selected targets and our capability of qualitatively and quantitatively determining unknown and new substances of emerging concern (also known as emerging substances) in human biofluids. As a result, non-targeted approaches have gained much attention in risk assessment of human exposure to unknown and emerging chemical contaminants. The goal of this project is to develop new non-targeted analytical methods, which aims to rapidly screen and identify new metabolites of these chemicals and some parent compounds in human biofluids as potential biomarkers for assessment of human exposure to substances, including CMP priority chemicals and other emerging chemicals.

  Results: Newly developed analytical methods will provide valuable screening information for metabolites and parent compounds as to the identification of potential emerging contaminants for future assessments under CMP. Models will be developed to provide semi-quantitative information of identified unknown chemicals without using standards. In addition, they will generate meaningful knowledge regarding metabolites derived from emerging chemicals in human biofluids.

  Publications: Feng, Y.-L., Liao, X., Chen, D., Takser, L., Cakmak, S., Chan, P., Zhu, J. 2020. Correlations of phthalate metabolites in urine samples from fertile and infertile men: Free-form concentration vs. conjugated-form concentration. Environmental Pollution, 2020, 263. 10.1016/j.envpol.2020.114602

  Guo, Z., Huang, S., Wang, J., Feng, Y.-L. 2020. Recent advances in non-targeted screening analysis using liquid chromatography - high resolution mass spectrometry to explore new biomarkers for human exposure. Talanta, 219 (2020) 121339. 10.1016/j.talanta.2020.121339

  Meshref, S., Li, Y., Feng Y.-L. 2020. Prediction of liquid chromatographic retention time using quantitative structure-retention relationships to assist non-targeted identification of unknown metabolites of phthalates in human urine with high-resolution mass spectrometry. 2020 J Chromatogr A,1634 (2020) 461691. DOI: 10.1016/j.chroma.2020.461691

7.1.2.2 Exposure Characterization

• Characterization of residential exposures to CMP metals and organics

  Focus of research: The study focuses primarily on childhood exposures to house dust through normal hand-to-mouth ingestion behavior, but also looks at potential inhalation exposures by characterizing metals in re-suspended house dust.

  Results: Settled house dust samples collected from 1025 homes in 13 cities under the Canadian House Dust Study (CHDS) were examined to provide a representative national baseline. Dust lead (Pb) concentrations and loadings from the CHDS were combined with smaller U.S. datasets to help support new, tighter U.S. Environmental Protection Agency standards for lead in dust on floors and window sills to protect children from the harmful effects of lead exposure. The house dust samples were analyzed for 16 bisphenol analogues. It was found that bisphenol A, S and F (BPA, BPS and BPF) were predominant.

  Publications: Glorennec P., Shendell D.G., Rasmussen P.E., Waeber R., Egeghy P., Azuma K., Pelfrêne A., Le Bot B., Esteve W., Perouel G., Pernelet Joly, V. Noack, Y., Delannoy M., Keirsbulck, M., Mandin C. (2020) Towards setting public health guidelines for chemicals in indoor settled dust? Indoor Air, DOI: 10.1111/ina.12722. DOI: 10.1111/ina.12722

  Bevington, C., Gardner, H.D., Cohen, J., Henning, C., Rasmussen, P.E. (2020) Relationship between Residential Dust-Lead Loading, and Dust-Lead Concentration across Multiple North American Datasets. Building and Environment. 188 DOI.org/10.1016/j.buildenv.2020.107359

  Fan, X., Katuri, G.P. Caza, A., Rasmussen, P.E., Kubwabo, C. 2020. Simultaneous measurement of 16 bisphenol analogues in house dust and evaluation of two sampling techniques. Emerging Contaminants vol 7. https://doi.org/10.1016/j.emcon.2020.12.001

• Multimedia exposure to replacement chemicals of emerging concern and selected CMP3 chemicals

  Focus of research: Many alternative chemicals have been introduced into the market as replacements for chemicals that have shown to exhibit a range of health effects. However, the exposure and potential health risks for these replacement chemicals have not yet been assessed in Canada. The goal of this project is to generate Canadian exposure data for a variety of priority compounds including bisphenol analogues, in environmental and biological matrices, as well as children’s products (such as, baby bottles).

  Results: An integrated and sensitive method was developed for the analysis of 16 bisphenol A (BPA) analogues in house dust. Bisphenol A (BPA) was detected in 100% of house dust samples. The BPA replacement chemicals, bisphenol S, bisphenol F and bisphenol M were detected in more than 75% of house dust samples. BPA and BPA replacement chemical concentrations in dust sampled from household vacuum bags compared well with concentrations observed in fresh dust collected from the same homes, suggesting that vacuum cleaner bag sampling could be a cost-effective alternative to fresh dust sampling in future studies.

  Publication: Fan, X., Katuri, G. P., Caza, A. A., Rasmussen, P. E., Kubwabo, C. 2021. Simultaneous measurement of 16 bisphenol A analogues in house dust and evaluation of two sampling techniques. Emerging Contaminants 7: 1-9. https://doi.org/10.1016/j.emcon.2020.12.001

7.1.2.3 Effects of chemicals on human health

• Hepatic investigation of vanadium toxicity

  Focus of research: Vanadium is considered as "possibly carcinogenic to humans" (V₂O₅, IARC Group 2B), yet uncertainties persist related to the toxicity mechanisms of the multiple forms of vanadium. Co-exposures of vanadium with polycyclic aromatic hydrocarbons (PAH) occurs in urbanized population and in occupational settings. PAH can be transformed to carcinogens by enzymes that are particularly abundant in the liver. Therefore, using two human liver cell lines (HepG2 and HepaRG) and aflatoxin-B1 (AFB1) (a mycotoxin) as a model chemical that is transformed into a carcinogen by liver enzymes, the current study investigated the ability of vanadium (in the soluble form of sodium metavanadate NaVO₃) to modulate the enzymatic activities required to transform AFB1 into a carcinogen.

  Results: Low concentration of NaVO₃ caused important cell proliferation only in HepaRG cells. As a binary mixture, NaVO₃ did not modify the effects of AFB1. High concentration of NaVO₃ increased DNA methylation in HepG2 cells. The fact that both cell lines responded differently to NaVO₃ supports the importance of investigating more than one cell line. Overall, the adverse effect of NaVO₃ might reside at low concentrations by stimulating the proliferation of tumorigenic cells.

  Publication: Desaulniers D., Cummings-Lorbetskie, C., Leingartner, K., Xiao, G.-H., Zhou, G., Parfett, C. 2021. Effects of vanadium (sodium metavanadate) and aflatoxin-B1 on cytochrome p450 activities, DNA damage and DNA methylation in human liver cell lines. Toxicology in Vitro (2021), 70: 105036. https://doi.org/10.1016/j.tiv.2020.105036

• Regional analysis of CHMS biomonitoring data

  Focus of research: The Canadian Health Measures Survey (CHMS) involves the collection of extensive data on blood and urinary concentration of environmental chemicals that are used to assess chemical exposures in Canadians. Although the data collected is only nationally representative within each cycle of CHMS, combining data from multiple cycles of the CHMS allows calculation of chemical concentrations that are representative at the regional level. The aim of this ongoing project is to develop statistically robust estimates of concentrations of chemicals at the regional level.

  Results: In the first-ever regional analysis of CHMS data, blood and/or urinary concentrations of several environmental chemicals for the provinces of Quebec and Ontario, were compared to concentrations in the rest of Canada. The analysis showed several regional differences in exposures to chemicals and helped assess contributing factors. The concentration of urinary fluoride was significantly higher in Ontario as compared to Quebec and the rest of Canada. Blood manganese and urinary fluoride were significantly lower in Quebec compared to the rest of Canada, and blood and urinary selenium were significantly lower in Ontario compared to the rest of Canada.

  Publication: Valcke, M., Karthikeyan, S., Walker, M., Gagné, M., Copes, R., St-Amand, A. 2020. Regional variations in human chemical exposures in Canada: A case study using biomonitoring data from the Canadian Health Measures Survey for the provinces of Quebec and Ontario. Int J Hyg Environ Health 225: 113451. DOI: 10.1016/j.ijheh.2020.113451.

• Maternal-Infant Research on Environmental Chemicals (MIREC) research platform

  Focus of research: The MIREC Research Platform is designed to obtain pan-Canadian data on maternal and fetal/early life exposure to priority environmental chemicals and potential adverse health effects on the pregnancy, as well as newborn and infant/childhood growth and development. It encompasses the original MIREC Study of Canadian pregnant women and the follow-up studies of some of their infants (MIREC-Infant Development: MIREC-ID), young children (MIREC-Child Development at age 3: MIREC-CD3 and MIREC- Early Childhood Biomonitoring and Neurodevelopment: MIREC-CD Plus) and now in adolescents (MIREC - Pubertal Timing, Endocrine and Metabolic Function: MIREC-ENDO). The Platform also includes a repository of MIREC data and biospecimens, the MIREC Biobank, for future research on the health of mothers and their children.

  Results: In 2020-2021, 10 MIREC research platform papers were published. This included studies of environmental exposures and outcomes in children and infants (preterm birth, the development of reproductive systems, BMI and cognitive outcomes) and pregnant women (gestational hypertension and preeclampsia). Some of these publications highlighted sex and gender based differences. For example, the effects of environmental chemicals on IQ were observed in boys but not in girls, and the effects of PFAS on gestational hypertension and preeclampsia depended on the sex of the fetus the mother was carrying. The project continues to generate new knowledge on early life cumulative exposure to endocrine disrupting chemicals and potential health risks in vulnerable populations of pregnant women, fetuses, infants, and young children that contributes to risk assessment and management of chemicals.

  Publications: Arbuckle, T.E., MacPherson, S.H., Fisher, M., Muckle, G., Foster, W., Sathyanarayana, S., Monnier, P., Lanphear, B., Fraser, W.D. 2020. Prenatal perfluoroalkyl substances and newborn anogenital distance in a Canadian cohort. Reprod Toxicol. 2020 Jun;94:31-39. https://doi.org/10.1016/j.reprotox.2020.03.011

  Borghese, M.M., Walker, M., Helewa, M.E., Fraser, W.D., Arbuckle, T.E. 2020. Association of perfluoroalkyl substances with gestational hypertension and preeclampsia in the MIREC study. Environment International, 141, art. no. 105789. 10.1016/j.envint.2020.105789

  Ashley-Martin, J., Dodds, L., Arbuckle, T.E., Lanphear, B., Muckle, G., Foster, W.G., Ayotte, P., Zidek, A., Asztalos, E., Bouchard, M.F., Kuhle, S. 2021. Urinary phthalates and body mass index in preschool children: The MIREC Child Development Plus study. International Journal of Hygiene and Environmental Health. Volume 232, March 2021, Article number 113689. https://doi.org/10.1016/j.ijheh.2021.113689

  Lukina, A.O., Fisher, M., Khoury, C., Than, J., Guay, M., Paradis, J.-F., Arbuckle, T.E., Legrand, M. 2021. Temporal variation of total mercury levels in the hair of pregnant women from the Maternal-Infant Research on Environmental Chemicals (MIREC) study. Chemosphere, 264, 128402.

  Cao X.L., Sparling, M., Zhao, W., and Arbuckle, T.E. 2021. GC-MS Analysis of Phthalates and Di-(2-thylhexyl) Adipate in Canadian Human Milk for Exposure Assessment of Infant Population. Journal of AOAC International 2021 Mar 5;104(1):98-102. DOI: 10.1093/jaoacint/qsaa108.

  Hu, J.M.Y., Arbuckle, T.E., Janssen, P., Lanphear, B.P., Braun, J.M., Platt, R.W., Chen, A., Fraser, W.D., McCandless, L.C. 2020. Associations of prenatal urinary phthalate exposure with preterm birth: the Maternal-Infant Research on Environmental Chemicals (MIREC) Study. Canadian Journal of Public Health, 111 (3), pp. 333-341. 10.17269/s41997-020-00322-5

  Romao, R.L.P., Dodds, L., Ashley-Martin, J., Monnier, P., Arbuckle, T.E. 2020. Prenatal exposure to phthalates and male reproductive system development: Results from a Canadian pregnancy cohort study. Reproductive Toxicology, 95, pp. 11-18. 10.1016/j.reprotox.2020.04.078

  Louopou, R.C., Trottier, H., Arbuckle, T.E., Fraser, W.D. 2020. Dental amalgams and risk of gestational hypertension in the MIREC study. Pregnancy Hypertension, 21, pp. 84-89. 10.1016/j.preghy.2020.04.015

  Nkinsa, P.N., Muckle, G., Ayotte, P., Lanphear, B.P., Arbuckle, T.E., Fraser, W.D., Bouchard, M.F. 2020. Organophosphate pesticide exposure during fetal development and IQ scores in 3 and 4-year old Canadian children. Environmental Research 2020 Aug 7:110023. 10.1016/j.envres.2020.110023.

  Azar, N., Booij, L,. Muckle, G., Arbuckle, T.E., Séguin, J.R., Asztalos, E., Fraser, W.D., Lanphear, B.P., Bouchard, M,F. 2020. Prenatal exposure to polybrominated diphenyl ethers (PBDEs) and cognitive ability in early childhood. Environ Int. 2021 Jan; 146:106296. Epub 2020 Dec. DOI: 10.1016/j.envint.2020.106296.

7.1.2.4 Nanomaterials

• The impact of dissolution behaviour of metal oxide nanomaterials on toxicological response

  Focus of research: The toxicological behavior of nanomaterials (NMs) is closely associated with their distinct physical-chemical properties. This research is investigating the influence of dissolution behaviour of NMs on their toxic potential.

  Results: Experimental results showed that the dissolution behaviour of three nano-metal oxides and their bulk analogues (nickel, zinc and copper) was different in cell culture medium compared to distilled water. By participating in an international validation exercise led by Germany under Project 1.4 of the Working Group of the National Coordinators for the Test Guidelines Programme (WNT), the HC research team contributed to the development of an OECD Test Guideline on Particle Size Distribution.

  Publications: Avramescu, M-L., Chénier, M., Palaniyandi, S., Rasmussen, P.E. 2020. Dissolution behaviour of metal oxide nanomaterials in cell culture medium versus distilled water. J. Nanoparticle Research, Vol. 22, 222 DOI: 10.1007/s11051-020-04949-w.

  Boyadzhiev, A., Avramescu, M.-L., Wu, D., Williams, A., Rasmussen, P., Halappanavar, S. 2021. Impact of copper oxide particle solubility on lung epithelial cell toxicity: response characterization using global transcriptional analysis. Nanotoxicology DOI: 10.1080/17435390.2021.1872114.

  Levesque, L., Wiseman, C.L.S., Beauchemin, S., Rasmussen, P.E. 2021. Thoracic Fraction (PM10) of Resuspended Urban Dust: Geochemistry, Particle Size Distribution and Lung Bioaccessibility. Geosciences 11, 87. DOI: 10.1080/17435390.2021.1872114.

• Relative toxic potency of silica and titanium dioxide nanoparticle variants

  Focus of research: The objective is to assess composition, size and surface coating characteristics of nanomaterial (NMs), and test toxicity in lung cells including cells from biopsy samples from healthy lungs and those affected by pulmonary diseases (for example, cystic fibrosis).

  Results: Influence of composition, size and surface coating characteristics of these NMs on their toxicity in lung epithelial cells and macrophages, and in cells from biopsy samples from healthy and pulmonary diseases (such as, cystic fibrosis) are being assessed. Oxidizing ability of these particles were determined. Also, uptake of amorphous silica nanoparticles into the macrophage cells were examined. This work will advance understanding of the health consequences of exposure to NMs, in providing toxicity information to contribute to the risk assessment of these materials, and can assist in the design of less toxic NMs.

  Publication: Breznan, D., Nazemof, N., Kunc, F., Hill, M., Vladisavljevic, D., Gomes, J., Johnston, L.J., Vincent, R., Kumarathasan, P. 2020. Acellular oxidative potential assay for screening of amorphous silica nanoparticles. Analyst. 2020 Jul 21;145(14):4867-4879. DOI: 10.1039/d0an00380h

• Characterization of metal nanoparticles

  Focus of Research: HC has identified a number of priority nanomaterials (NMs) on the Domestic Substances List (DSL), for which test data on physico-chemical characterization and toxicity are lacking for regulatory human health risk assessment. To fulfill these data needs, this research project was carried out to characterize the physico-chemical properties of several commercially available nano scale DSL substances, including aluminum oxide, copper oxide, titanium dioxide, and zinc oxide.

  Results: The characterizations of different nanoforms of the selected NMs were performed to determine their size, shape, surface area, surface charge, type and quantity of surface coating or surface modification. Data obtained from this project allow Health Canada to evaluate the relationships between NM properties and will allow for toxicological testing to determine if there are contrasting effects between nanoforms. The work will also serve to fill the data gaps for making regulatory decisions on the priority DSL NMs.

  Publication: Bushell, M., Beauchemin, S., Kunc, F., Gardner, D., Ovens, J., Toll, F., Kennedy, D., Nguyen, K., Vladisavljevic, D., Rasmussen, P.E., Johnston, L.J. 2020. Characterization of Commercial Metal Oxide Nanomaterials: Crystalline Phase, Particle Size and Specific Surface Area. Nanomaterials 2020, 10, 1812. DOI:10.3390/nano10091812

7.2 Air pollutants and greenhouse gases

Air quality research efforts help quantify priority air pollutants and determine trends, improve and validate air quality predictions both in the near term and into the future within the national and global context. These efforts also enhance understanding of the impacts of air pollution on Canadians and the environment. The research also tackles emerging issues, and underpins and informs evidence-based policy and regulatory development.

7.2.1 ECCC Research

Ongoing research continued on a wide range of air pollutants, including short-lived climate pollutants, ammonia, nitrogen oxides (NO_x), sulphur dioxide (SO₂), volatile organic compounds (VOCs), ozone, and particulate matter/aerosols. Over 44 research papers on the topics of air pollutants and GHGs were published in peer-reviewed scientific journals in 2020-2021. The following are representative examples of that body of work.

• Understanding atmospheric particulate matter

  Focus of research: Trends, characteristics and composition of atmospheric aerosols and trace elements in particulate matter in Canada

  Results: Three separate studies on atmospheric particulate matter indicated: 1) Analysis of samples from three monitoring stations in the Great Lakes Basin over a thirty-year span found concentrations of most trace elements in particulate matter were significantly decreased, but some levels are still close to or higher than acceptable cancer risk levels. 2) Long-term trends (2004–2017) in the chemical composition and sources of PM_2.5 (particulate matter smaller than 2.5 μm in diameter) in Toronto showed that non-tailpipe emissions (brake wear and resuspension of road dust) are rising, while the overall level of PM_2.5 has markedly decreased mainly due to reduced emissions from fossil fuel combustion and tailpipe emissions. Quantifying the oxidative potential of PM_2.5 from several Canadian cities found that traffic emissions resulted in the highest oxidative potential, followed by industrial emissions and resuspended crustal matter.

  Publications: Li, W., Dryfhout-Clark, H., Hung, H. 2020. PM₁₀-bound trace elements in the Great Lakes Basin (1988–2017) indicates effectiveness of regulatory actions, variations in sources and reduction in human health risks. Environment International, art. no. 106008, 10.1016/j.envint.2020.106008.

  Jeong, C.-H., Traub, A., Huang, A., Hilker, N., Wang, J.M., Herod, D., Dabek-Zlotorzynska, E., Celo, V., Evans, G.J. 2020. Long-term analysis of PM_2.5 from 2004 to 2017 in Toronto: Composition, sources, and oxidative potential. Environmental Pollution, 263, art. no. 114652. DOI: 10.1016/j.envpol.2020.114652

  Shahpoury, P., Zhang, Z.W., Arangio, A., Celo, V., Dabek-Zlotorzynska, E., Harner, T., Nenes, A. 2020. The influence of chemical composition, aerosol acidity, and metal dissolution on the oxidative potential of fine particulate matter and redox potential of the lung lining fluid (2021) Environment International, 148, art. no. 106343, DOI: 10.1016/j.envint.2020.106343

• Emissions and trends of ammonia, sulphur oxides and nitrogen oxides

  Focus of research: Improved emissions estimates through satellite measurements.

  Results: 1) A global study identified regions of high or changing ammonia concentrations and linked these to various human activities; high emission areas in North America were characterized by high agricultural activity. 2) A comparison of satellite-derived and reported sulphur dioxide (SO₂) emissions from the Canadian oil sands found that although satellite-derived SO₂ emissions remained relatively constant since 2013, reported emissions dropped by a factor of two; no clear explanation for the discrepancy was found. 3) Analysis of satellite measurements of nitrogen dioxide (NO₂) combined with air quality modelling estimated a 40% decrease in NO₂ emissions in the Greater Toronto Area due to COVID-19 related reductions on vehicle and aircraft traffic and on industry.

  Publications: Evangeliou, N., Balkanski, Y., Eckhardt, S., Cozic, A., Van Damme, M., Coheur, P.-F., Clarisse, L., Shephard, M. W., Cady-Pereira, K. E., and Hauglustaine, D. 2021. 10-year satellite-constrained fluxes of ammonia improve performance of chemistry transport models. Atmos. Chem. Phys., 21, 4431–4451, https://doi.org/10.5194/acp-21-4431-2021, 2021.

  McLinden, C.A., Adams, C.L.F., Fioletov, V., Griffin, D., Makar, P.A., Zhao, X., Kovachik, A., Dickson, N., Brown, C., Krotkov, N., Li, C., Theys, N., Hedelt, P., Loyola, D.G. 2021. Inconsistencies in sulfur dioxide emissions from the Canadian oil sands and potential implications. Env. Res. Lett., 16 (1), art. no. 014012

  Griffin, D.; McLinden, C.A.; Racine, J.; Moran, M.D.; Fioletov, V.; Pavlovic, R.; Mashayekhi, R.; Zhao, X.; Eskes, H. 2020. Assessing the Impact of Corona-Virus-19 on Nitrogen Dioxide Levels over Southern Ontario, Canada. Remote Sens. 12, 4112.

  Feng, J., Vet, R., Cole, A., Zhang, L., Cheng, I., O'Brien, J., Macdonald, A.-M. 2021. Inorganic chemical components in precipitation in the eastern U.S. and Eastern Canada during 1989–2016: Temporal and regional trends of wet concentration and wet deposition from the NADP and CAPMoN measurements. Atmospheric Environment, 254, art. no. 118367, DOI: 10.1016/j.atmosenv.2021.118367

• Observing historic lows in tropospheric and stratospheric ozone levels

  Focus of research: Long-term monitoring of trends in atmospheric ozone concentrations.

  Results: Observed tropospheric ozone in the northern hemisphere in the spring and summer of 2020 was the lowest in at least 20 years. This was linked to COVID-19 related emissions reductions. A record seasonal loss of stratospheric ozone was observed over the Arctic in spring 2020. This was determined to be due to unusually low temperatures, demonstrating that weather may cause short-term reversals in the long-term improvement in ozone levels as the use of ozone-depleting substances declines.

  Publications: Steinbrecht, W., Kubistin, D., Plass-Dülmer, C., Davies, J., Tarasick, D.W., Gathen, P.V.D., Deckelmann, H., Jepsen, N., Kivi, R., Lyall, N., Palm, M., Notholt, J., Kois, B., Oelsner, P., Allaart, M., Piters, A., Gill, M., Van Malderen, R., Delcloo, A.W., Sussmann, R., Mahieu, E., Servais, C., Romanens, G., Stübi, R., Ancellet, G., Godin-Beekmann, S., Yamanouchi, S., Strong, K., Johnson, B., Cullis, P., Petropavlovskikh, I., Hannigan, J.W., Hernandez, J.-L., Diaz Rodriguez, A., Nakano, T., Chouza, F., Leblanc, T., Torres, C., Garcia, O., Röhling, A.N., Schneider, M., Blumenstock, T., Tully, M., Paton-Walsh, C., Jones, N., Querel, R., Strahan, S., Stauffer, R.M., Thompson, A.M., Inness, A., Engelen, R., Chang, K.-L., Cooper, O.R. 2021. COVID-19 Crisis Reduces Free Tropospheric Ozone Across the Northern Hemisphere. Geophys. Res. Lett., 48 (5), art. no. e2020GL091987, DOI: 10.1029/2020GL091987

  Wohltmann, I., von der Gathen, P., Lehmann, R., Maturilli, M., Deckelmann, H., Manney, G.L., Davies, J., Tarasick, D., Jepsen, N., Kivi, R., Lyall, N., Rex, M. 2020. Near-Complete Local Reduction of Arctic Stratospheric Ozone by Severe Chemical Loss in Spring 2020. Geophysical Research Letters, 47 (20), art. no. e2020GL089547, DOI: 10.1029/2020GL089547

• Emissions from oil and gas operations

  Focus of research: Improving air pollutant emissions estimates from Canadian oil and gas operations and understanding the sources and composition of air pollution events in the Athabasca oil sands.

  Results: A study was conducted of air pollution events in the Athabasca oil sands region to characterize the components of complex air pollutant mixtures and to identify pollution sources. The study found that these events often involve multiple chemical mixtures, indicating limitations to current risk assessments that are based on a small number of air quality standards. Atmospheric measurements and modelling produced improved estimates of methane emissions from Canadian oil and gas operations, which were significantly higher than those reported to inventories.

  Publications: Wren, S.N., Mihele, C.M., Lu, G., Jiang, Z., Wen, D., Hayden, K., Mittermeier, R.L., Staebler, R.M., Cober, S.G., Brook, J.R. 2020. Improving Insights on Air Pollutant Mixtures and Their Origins by Enhancing Local Monitoring in an Area of Intensive Resource Development. Environ. Sci. Technol. 2020, 54, 23, 14936–14945, DOI: 10.1021/acs.est.0c06055.

  Chan, E., Worthy, D.E.J., Chan, D., Ishizawa, M., Moran, M.D., Delcloo, A., Vogel, F. 2020. Eight-Year Estimates of Methane Emissions from Oil and Gas Operations in Western Canada Are Nearly Twice Those Reported in Inventories. Environ. Sci. Technol. 2020, 54, 14899−14909, DOI: 10.1021/acs.est.0c04117

• Atmospheric emissions from wildfires and other biomass burning

  Focus of research: Understanding the composition and chemical transformations, long-range transport and global warming impacts of emissions from wildfires and other burning of biomass

  Results: A study of the chemical composition and atmospheric chemical reactions associated with wildfire smoke found a complex mixture of diverse organic compounds. Studies of emissions from wildfires and anthropogenic biomass burning activities demonstrated the long-range transport of these emissions, with increased tropospheric ozone generated from transformations of wildfire smoke measured far from the source. In addition, carbon monoxide and fine particulate matter from wildfires in Siberia were found in western Canada.

  Publications: Ditto, J. C., He, M., Hass-Mitchell, T. N., Moussa, S. G., Hayden, K., Li, S.-M., Liggio, J., Leithead, A., Lee, P., Wheeler, M. J., Wentzell, J. J. B., and Gentner, D. R. 2021. Atmospheric evolution of emissions from a boreal forest fire: the formation of highly functionalized oxygen-, nitrogen-, and sulfur-containing organic compounds. Atmos. Chem. Phys., 21, 255–267, https://doi.org/10.5194/acp-21-255-2021.

  Moeini, O., Tarasick, D.W., McElroy, C.T., Liu, J., Osman, M.K., Thompson, A.M., Parrington, M., Palmer, P.I., Johnson, B., Oltmans, S.J., Merrill, J. 2020. Estimating wildfire-generated ozone over North America using ozonesonde profiles and a differential back trajectory technique. Atmospheric Environment: X, 7, art. no. 100078, DOI: 10.1016/j.aeaoa.2020.100078

  Tao, J., Surapipith, V., Han, Z., Prapamontol, T., Kawichai, S., Zhang, L., Zhang, Z., Wu, Y., Li, J., Li, J., Yang, Y., Zhang, R. (2020) High mass absorption efficiency of carbonaceous aerosols during the biomass burning season in Chiang Mai of northern Thailand. Atmospheric Environment, 240, art. no. 117821, 10.1016/j.atmosenv.2020.117821.

  Johnson, M.S., Strawbridge, K., Knowland, K.E., Keller, C., Travis, M. 2021. Long-range transport of Siberian biomass burning emissions to North America during FIREX-AQ. Atmos. Environ., 252, art. no. 118241, DOI: 10.1016/j.atmosenv.2021.118241

7.2.2 Health Canada research

In 2020-2021, HC continued to conduct research on human exposure to indoor and outdoor air pollutants and their health impacts in order to guide actions to address air pollution by governments, industries, other organizations and individuals. HC scientists published approximately 58 articles in peer reviewed scientific journals. These addressed issues such as implications of air pollution exposure on the number of COVID-19 cases in communities; the effect of air pollutants on birth outcomes and on the development of diseases such as asthma, diabetes, and cancer; the risks associated with elevated exposure to traffic and industrial pollutants; and the interactions between air pollution and physiological and psychological stress.

The following includes a list of some of the projects in which HC was engaged in during 2020-2021.

• Role of non-chemical stressors and stress susceptibility in modifying the effects of air pollutants on health

  Focus of research: Non-chemical stressors are important determinants of health that may also modify or contribute to the adverse health effects associated with air pollution. The objective is to assess the extent to which non-chemical stressors and inter-individual differences in stress response modify health effects of air pollution.

  Results: The study produced the first evidence that individual differences in stress reactivity are associated with differential sensitivity to pulmonary impacts of ozone. The first national profile of allostatic load, a measure of cumulative physiological dysfunction associated with chronic exposure to stressors, was published. Results identified a spatial association between psychological distress and ambient air pollution levels in Canada. Poor mental health was associated with increased risk of mortality from air pollutants in the Canadian population. This work provides insight into factors governing susceptibility to inhaled pollutants. The allostatic load profile provides a tool for assessing combined and cumulative impacts of exposure to multiple stressors.

  Publications: Pinault L., Thomson, E.M. Christidis, T., Colman, I., Tjepkema, M., van Donkelaar, A., Martin, R.V., Hystad, P., Shin, H., Crouse, D.L., Burnett, R.T. 2020. The association between ambient air pollution concentrations and psychological distress. Health Rep. 2020 Jul 29;31(7):3-11. DOI: 10.25318/82-003-x202000700001-eng. PMID: 32761579.

  Thomson, E.M., Christidis, T., Pinault, L., Tjepkema, M., Colman, I., Crouse, D.L., van Donkelaar, A., Martin, R.V., Hystad, P., Robichaud, A., Ménard, R., Brook, J.R., Burnett, R.T. 2020. Self-rated stress, distress, mental health, and health as modifiers of the association between long-term exposure to ambient pollutants and mortality. Environ Res. 2020 Aug 15;191:109973. DOI: 10.1016/j.envres.2020.109973.

  Crouse, D.L., Pinault, L., Christidis, T., Lavigne, E., Thomson, E.M., Villeneuve, P.J. 2021. Residential greenness and indicators of stress and mental well-being in a Canadian national-level survey. Environ Res. 2021 Jan;192:110267. DOI: 10.1016/j.envres.2020.110267. Epub 2020 Oct 4. DOI: 10.1016/j.envres.2020.110267

  Willey J.B., Pollock, T., Thomson, E.M., Liang, C.L., Maquiling, A., Walker, M., St-Amand, A. 2021. Exposure Load: Using biomonitoring data to quantify multi-chemical exposure burden in a population. Int J Hyg Environ Health. 2021 May;234:113704. DOI: 10.1016/j.ijheh.2021.113704. Epub 2021 Mar 6. PMID: 33690093-21.

• Role of stress and stress reactivity in mediating impacts of air pollutants on the brain and lungs

  Focus of research: Exposure to air pollution is associated with increased risk of neurological and mental health disorders, but underlying mechanisms are unclear. The brain is exquisitely sensitive to stress, and chronic stress exerts profound biochemical and structural effects on the brain that contribute to local and systemic disease processes. This project investigates the role of stress responses in mediating impacts of pollutant inhalation on the brain and lungs, using in vivo and in vitro models, a human chamber study, and a birth cohort.

  Results: Study findings directly link pollutant-induced release of stress hormones with effects in the brain. These findings substantiate the hypothesis that activation of the stress axis is involved in mediating adverse central nervous system impacts of air pollutants. Experimental work showed that air pollution produced effects in the brain that have been associated with reduced cognitive function and depression. Exposure to diesel exhaust increased blood cortisol levels, particularly in people diagnosed with asthma or with genetic variations that impact their ability to mount an antioxidant response. Brain imaging of a cohort of preadolescents showed associations between air pollution exposure and brain morphology, with patterns broadly consistent with effect of early-life stress. By linking results from experimental models to humans, ongoing work will provide mechanistic support for the causal basis of epidemiological associations, and inform effective risk assessment and management strategies through identification of characteristics that underlie vulnerability.

  Publications: Rose, M., Filiatreault, A., Guénette, J., Williams, A., Thomson, E.M. 2020. Ozone Increases Plasma Kynurenine-Tryptophan Ratio and Impacts Hippocampal Serotonin Receptor and Neurotrophic Factor Expression: Role of Stress Hormones. Environ Res. 2020 Jun;185:109483. DOI: 10.1016/j.envres.2020.109483

  Lubczyńska, M,J,, Muetzel, R.L., El Marroun, H., Hoek, G., Kooter, I.M., Thomson, E.M., Hillegers, M., Vernooij, M.W., White, T., Tiemeier, H., Guxens, M. 2020. Air pollution exposure during pregnancy and childhood and brain morphology in preadolescents. Environ Res. 2020 Nov 19:110446. DOI: 10.1016/j.envres.2020.110446

  Thomson, E.M., Filiatreault, A., Williams, A., Rider, C.F., Carlsten, C. 2021. Exposure to Diesel Exhaust and Plasma Cortisol Response: A Randomized Double-Blind Crossover Study. Environ Health Perspect. 2021 Mar;129(3):37701. DOI: 10.1289/EHP8923. Epub 2021 Mar 26. PMID: 33769847; PMCID: PMC7997608

• Air Quality Health Index and other communications tools

  Focus of research: The Air Quality Health Index (AQHI) is the Government of Canada’s tool to communicate daily air quality conditions and forecasts to Canadians. It was developed by HC as a means to convey to the public the health risk associated with the air pollution mixture and to guide actions by individuals and organizations to address episodes when the risk is elevated. In order to remain accurate and relevant ongoing scientific research is needed to evaluate, update and improve the AQHI.

  Results: The AQHI was originally formulated based on the association of three air pollutants with increased risk of all-cause mortality. Further investigations have demonstrated that the index also reflects other health outcomes such as emergency department visits. Wildfires smoke and residential wood combustion present specific circumstances for the deterioration in air quality and communication tools to specifically address these conditions are needed.

  Publications: Trieu, J, Yao, J., McLean, K.E., Stieb, D.M., Henderson, S.B. 2020. Evaluating an Air Quality Health Index (AQHI) amendment for communities impacted by residential woodsmoke in British Columbia, Canada. J Air Waste Manag Assoc. 2020 Oct;70(10):1009-1021. DOI: 10.1080/10962247.2020.1797927.

  Szyszkowicz, M. 2020. The air quality health index and emergency department visits for injury. Polish J Pubic Health. 130(1):52-56. DOI: 10.2478/pjph-2020-0012.

• Long-term exposure to industrial air pollution emissions and the incidence of childhood asthma, and adult hypertension and diabetes

  Focus of research: Industrial emissions are important sources of ambient air pollution, and contribute to local and regional air pollutant concentrations. However, knowledge on the scale of population health impact by Canadian industrial emissions is still limited. Asthma has been reported to be affected by air pollution. In collaboration with the Institut National de Santé Publique du Québec and universities, HC studied the long-term exposure of all children born in the province of Quebec, Canada, between 2002 and 2011, to outdoor fine particulate matter (PM_2.5), sulphur dioxide (SO₂) and nitrogen dioxide (NO₂) emitted from industrial sources. The study focused on whether these exposures were related to incident cases of childhood asthma.

  Results: The study found that long-term exposure to outdoor air pollutants emitted from industrial sources may lead to increased new cases of childhood asthma. Specifically, increases in PM_2.5, SO₂, and NO₂ from 25th to 75th percentile in outdoor concentrations were significantly associated with 19% to 23% increase in new cases of childhood asthma.

  Publication: Buteau, S., Shekarrizfard, M., Hatzopolou, M., Gamache, P., Liu, L., Smargiassi, A. 2020. Air pollution from industries and asthma onset in childhood: a population-based birth cohort study using dispersion modeling. Environ.Res. june 2020. 185:109180. https://doi.org/10.1016/j.envres.2020.109180.

• Exposure to outdoor air pollution and risk of fatal cardiac arrhythmias in patients with implantable cardio defibrillators (ICDs)

  Focus of research: The influence of daily changes in air pollution in the province of Ontario, Canada on the frequency of discharges from implantable cardio defibrillators (ICDs), which occur in response to potentially life threatening arrhythmias, were assessed.

  Results: No evidence was found that the concentrations of ambient air pollution observed in the study were a risk factor for potentially fatal cardiac arrhythmias in patients with ICDs.

  Publication: Dales, R., Lee, D.S.., Wang, X., Cakmak, S., Szyszkowicz, M., Shutt, R., Birnie, D. 2020. Do acute changes in ambient air pollution increase the risk of potentially fatal cardiac arrhythmias in patients with implantable cardioverter defibrillators? Environ Heal A Glob Access Sci Source. 2020;19(1). https://doi.org/10.1186/s12940-020-00622-w.

• Blood volatile organic compounds (VOCs) and changes in hematologic and biochemical profiles

  Focus of research: The influence of volatile organic compound (VOC) levels in blood, on hematological and serum biochemical parameters in the Canadian population was investigated.

  Results: This study provides evidence that VOCs in blood, at levels found in the Canadian population, may influence blood cell counts and indicators of liver and kidney function. The study showed an inverse association between serum VOC and creatinine.

  Publication: Cakmak, S., Cole, C., Hebbern, C., Andrade, J., Dales, R. 2020. Associations between blood volatile organic compounds, and changes in hematologic and biochemical profiles, in a population-based study. Environment International, 145, 106121. https://doi.org/10.1016/j.envint.2020.106121.

• Factors influencing volatile organic compounds in Canadian homes

  Focus of research: Volatile organic compounds, several of which may impact health, have many possible indoor sources. To further investigate this, we tested the association between indoor concentrations of 47 passively collected volatile organic compounds and both home characteristics and occupant behaviours in a Canadian population-based sample of 3454 participants.

  Results: Homes with a door connecting to an attached garage had greater concentrations of hexanal, benzaldehyde, all the measured alkyl benzenes and ketones, most of the simple hydrocarbons and terpenes. Major home renovations within the past month were associated with higher concentrations of most or all of the volatile organic compounds in the categories of alcohols, alkyl benzenes, ketones, simple hydrocarbons and terpenes. Using paints and stains within the past week were associated with an increase in concentrations of the majority of alcohols, alkyl benzenes and simple hydrocarbons. Several building characteristics and occupant’s behaviours appear to increase exposure to volatile organic compounds.

  Publication: Cakmak, S., Kauri, L. M., Andrade, J., & Dales, R. 2020. Factors influencing volatile organic compounds in Canadian homes. Indoor and Built Environment, 1420326X2092622. https://doi.org/10.1177/1420326X20926229.

• Health effects of exposure to ultrafine particles (UFPs)

  Focus of research: This study investigates long-term exposure to UFPs on the risk of developing cancer in adults and children using data from case-control and cohort studies.

  Results: Childhood exposure to UFPs and the development of childhood cancers was investigated in the city of Toronto. Ambient UFPs exposure during the first trimester of pregnancy was positively associated with overall childhood cancer incidence before 6 years of age.

  Publication: Lavigne, E., Lima, I., Hatzopoulou, M., Van Ryswyk, K., van Donkelaar, A., Martin, R.V., Chen, H., Stieb, D.M., Crighton, E., Burnett, R.T., Weichenthal, S. 2020. Ambient ultrafine particle concentrations and incidence of childhood cancers. Environment International. 2020 Dec 1;145:106135

• Multi-City Multi-Country (MCC) Collaborative Research Network

  Focus of research: Numerous studies have examined the associations between short-term particulate matter (PM) exposures and daily mortality. However, most evidence has been obtained from studies in single cities, regions, or countries. There are challenges in comparing these results and in synthesizing effect estimates because of different modeling approaches and potential publication bias. The MCC Collaborative Research Network was designed to address these limitations by performing international, multicenter studies that adopt the same analytic protocol and model specifications to estimate globally representative associations of ozone, PM₁₀ and PM_2.5 exposures with daily mortality.

  Results: The research provides key evidence on the independent and linear associations between short-term exposure to NO₂ and increased risk of total, cardiovascular, and respiratory mortality.

  Publication: Meng, X., Liu, C., Chen, R., Sera, F., Vicedo-Cabrera, A.M., Milojevic, A., Guo, Y., Tong, S., Coelho, M.D., Saldiva, P.H., Lavigne, E. 2021. Short term associations of ambient nitrogen dioxide with daily total, cardiovascular, and respiratory mortality: multilocation analysis in 398 cities. bmj. 2021 Mar 24;372.

• Air Pollution Exposure linked to the Ontario Population Health and Environment Cohort

  Focus of research: The Ontario Population Health and Environment Cohort (ONPHEC) is a large, retrospective cohort in the province of Ontario, created in 2014 by linking multiple large-scale health administrative databases. It is comprised of virtually the entire Canadian-born population of Ontario who were 35 years or older in 1996 (around 4.9 million), with follow-up until 2014. The primary objectives of ONPHEC are to investigate the independent and combined effects of environmental stressors (such as air pollution, traffic-related noise) on the incidence of chronic diseases and their interactions with ‘healthy’ environmental factors (for example, green areas).

  Results: The research found that air pollution was associated with a higher incidence of chronic obstructive pulmonary disease (COPD) but was not associated with a higher incidence of adult-onset asthma.

  Publication: Shin, S., Bai, L., Burnett, R.T., Kwong, J.C., Hystad, P., van Donkelaar, A., Lavigne, E., Weichenthal, S., Copes, R., Tu, K., Martin, R.V., Kopp, A., and Chen, H. 2021. Air Pollution as a Risk Factor for Incident Chronic Obstructive Pulmonary Disease and Asthma: 15-Year Population-Based Cohort Study. American Journal of Respiratory and Critical Care Medicine. May 1;203(9):1138-1148. DOI: 10.1164/rccm.201909-1744OC.

• Health impacts of wildfire smoke

  Focus of research: Air pollution from wildfires poses a serious health risk for Canadians, particularly from May to September. Wind can carry harmful smoke long distances from wildfires, affecting communities thousands of kilometers away.

  Results: HC, ECCC, and the BC Centre for Disease Control used results from ECCC’s FireWork model to estimate the impact of wildfires on air quality. These estimates were then used as input into HC’s Air Quality Benefits Assessment Tool (AQBAT) to estimate the mortality rate and other health impacts specifically caused by wildfire smoke. The study found that in a 5-year period hundreds to thousands of deaths and many more illnesses annually are attributable to air pollution from wildfires.

  Publication: Matz, C.J., Egyed, M., Xi, G., Racine, J., Pavlovic, R., Rittmaster, R,. Henderson, S.B., Stieb, D.M. 2020. Health impact analysis of PM_2.5 from wildfire smoke in Canada (2013-2015, 2017-2018). Sci Total Environ. 2020 Jul 10;725:138506. DOI: 10.1016/j.scitotenv.2020.138506.

• Traffic-related air pollution

  Focus of research: Traffic-Related Air Pollution (TRAP) is one of the major sources of air pollution exposure in urban areas. Much of the Canadian population is regularly exposed to TRAP as a result of daily activities, such as commuting, and a significant portion of the population resides in close proximity to major roadways. Investigation of the health impacts of TRAP can guide future air quality management measures and identify the role of pollutants versus noise and other built environment factors.

  Results: Improved understanding of how exposure to air pollution while commuting contributes to health risk estimation. Two systematic reviews and meta-analyses allow the integration of research results from multiple studies and the evaluation of the impact of TRAP on population health. Original studies found links between TRAP exposure and the development of cardiovascular disease suggesting part of the mechanism by which pollution leads to severe illness and death.

  Publications: Stieb, D.M., Zheng, C. Salama, D., Berjawi, R., Emode, M., Hocking, R., Lyrette, N., Matz, C., Lavigne, E., Shin, H.H. 2020. Systematic review and meta-analysis of case-crossover and time-series studies of short term outdoor nitrogen dioxide exposure and ischemic heart disease morbidity. Environ Health. 2020 May 1;19(1):47. DOI: 10.1186/s12940-020-00601-1.

  Stieb DM, Berjawi R, Emode M, Zheng C, Salama D, Hocking R, Lyrette N, Matz C, Lavigne E, Shin HH. Systematic review and meta-analysis of cohort studies of long term outdoor nitrogen dioxide exposure and mortality. PLoS One. 2021 Feb 4;16(2):e0246451. DOI: 10.1371/journal.pone.0246451.

  Van Ryswyk, K., Evans, G.J., Kulka, R, Sun, L., Sabaliauskas, K., Rouleau, M., Anastasopolos, A.T., Wallace, L., Weichenthal, S. 2020. Personal exposures to traffic-related air pollution in three Canadian bus transit systems: the Urban Transportation Exposure Study. Journal of Exposure Science & Environmental Epidemiology. 2020 Jul 16:1-3.

  Johnson, M., Brook, J.R., Brook, R.D., Oiamo, T.H., Luginaah, I., Peters, P.A., Spence, J.D. 2020. Traffic-related air pollution and carotid plaque burden in a Canadian city with low-level ambient pollution. Journal of the American Heart Association. 2020 Apr 9;9(7):e013400.

  Bai, L., Shin, S., Oiamo, T.H., Burnett, R.T., Weichenthal, S., Jerrett, M., Kwong, J.C., Copes, R., Kopp, A., Chen, H. 2020. Exposure to road traffic noise and incidence of acute myocardial infarction and congestive heart failure: a population-based cohort study in Toronto, Canada. Environmental health perspectives. 2020 Aug 12;128(8):087001.

• Health impacts of early life exposure to air pollution

  Focus of research: Exposure to air pollution in-utero and throughout childhood is believed to contribute to many adverse health outcomes including immune related diseases. Several approaches are being undertaken to elucidate this relationship using different methods to characterize air pollution exposure and link it to birth outcomes and childhood disease.

  Results: Air pollution was seen to increase the risk of adverse health outcomes at birth and in early childhood development across several different research methods and considering pollutants from different sources. Studies identified links with the development of asthma, inflammatory bowel disease and early-onset paediatric type 1 diabetes.

  Publications: Nielsen, C.C., Amrhein, C.G., Shah, P.S., Stieb, D.M., Osornio-Vargas, A.R.; Canadian Neonatal Network, DoMiNO Team. 2020. Space-time hot spots of critically ill small for gestational age newborns and industrial air pollutants in major metropolitan areas of Canada. Environ Res. 2020 Jul;186:109472. DOI: 10.1016/j.envres.2020.109472.

  Lavigne, É., Talarico, R., van Donkelaar, A., Martin, R.V., Stieb, D.M., Crighton, E., Weichenthal, S., Smith-Doiron, M., Burnett, R.T., Chen, H. 2021. Fine particulate matter concentration and composition and the incidence of childhood asthma. Environment International. 2021 Jul 1;152:106486.

  Elten, M., Benchimol, E.I., Fell, D.B., Kuenzig, M.E., Smith, G., Chen, H., Kaplan, G.G., Lavigne, E. 2020. Ambient air pollution and the risk of pediatric-onset inflammatory bowel disease: A population-based cohort study. Environment international. 2020 May 1;138:105676.

  Elten, M., Donelle, J., Lima, I., Burnett, R.T., Weichenthal, S., Stieb, D.M., Hystad, P., van Donkelaar, A,, Chen, H., Paul, L.A., Crighton, E. 2020. Ambient air pollution and incidence of early-onset paediatric type 1 diabetes: A retrospective population-based cohort study. Environmental research. 2020 May 1;184:109291

• Air pollution and the built environment

  Focus of research: The impact of air pollution on health cannot be addressed without consideration of other environmental factors and processes that interact with it, both in the environment itself and through the body’s response to multiple stressors, like noise, allergens, heat, and other circumstance. The built environment can be a mediator of air pollution health impacts both directly and by influencing distribution of populations made vulnerable by socioeconomic status. A better understanding of these relationships is needed to support risk assessments, and to provide guidance to policy makers in urban planning for green space, transportation, and neighbourhood design.

  Results: Green space is an important characteristic of the urban landscape that can be beneficial to health directly by moderating heat, noise and air pollution. In investigations of the association of greenspace on health outcomes, increased exposure to urban green space was associated with reduced incidence of dementia and stroke. Living in urban areas with more green spaces was associated with improved cardiovascular health in people free of acute myocardial infarction (AMI) and heart failure (HF), but not among individuals who have already developed these conditions.

  Publications: Paul, L.A., Hystad, P., Burnett, R.T., Kwong, J.C., Crouse, D.L., van Donkelaar, A., Tu, K., Lavigne, E., Copes, R., Martin, R.V., Chen, H. 2020. Urban green space and the risks of dementia and stroke. Environmental research. 2020 Jul 1;186:109520.

  Chen, H., Burnett, R.T., Bai, L., Kwong, J.C., Crouse, D.L., Lavigne, E., Goldberg, M.S., Copes, R., Benmarhnia, T., Ilango, S.D., van Donkelaar, A. 2020. Residential greenness and cardiovascular disease incidence, readmission, and mortality. Environmental health perspectives. 2020 Aug 25;128(8):087005

• Outdoor Pollution Exposure Risk Assessment (OPERA)

  Focus of research: Outdoor Pollution Exposure and Risk Assessment (OPERA) represents a new paradigm in how to conduct burden of disease studies to support evidence-based decision making in climate and air quality management. The project consists of two main components: construction of multi-pollutant concentration response functions for different health outcomes; and estimation of disease burden by source of pollution and geographic area.

  Results: Improved air pollution exposure methodologies were applied to Canadian and global cohorts and found associations between air pollution exposure for a range of health outcomes including diabetes, preterm birth and mortality. A large international collaboration has made a significant contribution to the estimation of the global burden of disease associated with air pollution. The toxic action of particulate matter can be better understood by evaluation of the chemical components that contribute to oxidative stress in the lungs. Epidemiological studies in Toronto have found associations between long term exposure to metals characteristic of non-tailpipe vehicle emissions and respiratory and cardiovascular disease outcomes. A study on Quebec population cohort found that the onset of dementia may be related to residential long-term exposure to PM_2.5, NO₂, and distance to major roads.

  Publications: Zhang, Z., Weichenthal, S., Kwong, J.C., Burnett, R.T., Hatzopoulou, M., Jerrett, M., van Donkelaar, A., Bai, L., Martin, R.V., Copes, R., Lu, H. 2021. A Population-Based Cohort Study of Respiratory Disease and Long-Term Exposure to Iron and Copper in Fine Particulate Air Pollution and Their Combined Impact on Reactive Oxygen Species Generation in Human Lungs. Environmental Science & Technology. 2021 Mar 5;55(6):3807-18.

  Zhang, Z., Weichenthal, S., Kwong, J.C., Burnett, R.T., Hatzopoulou, M., Jerrett, M., Donkelaar, A.V., Bai, L., Martin, R.V., Copes, R., Lu, H. 2021. Long-term exposure to iron and copper in fine particulate air pollution and their combined impact on reactive oxygen species concentration in lung fluid: a population-based cohort study of cardiovascular disease incidence and mortality in Toronto, Canada. International Journal of Epidemiology. 2021 Apr;50(2):589-601.

  Gao, D., Ripley, S., Weichenthal, S., Pollitt, K.J. 2020. Ambient particulate matter oxidative potential: Chemical determinants, associated health effects, and strategies for risk management. Free Radical Biology and Medicine. 2020 May 1;151:7-25.

  Smargiassi, A., Sidi, E.A.L., Robert, L.-E., Plante, C., Haddad, M. Gamache, P., Burnett, R., Goudreau, S., Liu, L., Fournier, M., Pelletier, E., Yankoty, I., 2020. Exposure to ambient air pollutants and the onset of dementia in Québec, Canada. Environ. Res. 2020. 190:109870. https://doi.org/10.1016/j.envres.2020.109870.

• Methods Development for Modelling Concentration-Response Function

  Focus of research: New evidence is emerging that relationships between outdoor concentrations of air pollutants and health may not all be best characterized by linear risk models. This project will develop mathematical methods to combine results from several studies with non-linear associations between air pollution exposure and health.

  Results: This study investigates the association between ambient air pollution concentration levels and emergency department visits for personality disorders, acute reaction to stress, and disturbance of conduct using a non-linear modeling technique. The study suggested an impact of urban air pollution, mainly fine particulate matter, on human behaviour.

  Publications: Szyszkowicz, M. 2020. Application of quantile regression in environmental epidemiology. Polish J Pubic Health. 129(3):72-74. https://doi.org/10.2478/pjph-2019-0017.

  Szyszkowicz, M., Zemek, R., Colman, I., Gardner, W., Kousha, T., Smith-Doiron, M. 2020. Air Pollution and Emergency Department Visits for Mental Disorders among Youth. Int J Environ Res Public Health. 17(12):4190. DOI: 10.3390/ijerph17124190

• Air Pollution and COVID-19

  Focus of research: Studies from the United States and Europe suggested that both short and long-term exposure to air pollution may increase the incidence of and mortality from COVID-19. This study examined whether the number of cases of COVID-19 infection is related to air pollution levels among 111 Canadian health regions, as well as 140 Toronto neighbourhoods, adjusting for other factors such as race, income, weather, population density and time since the peak number of cases.

  Results: The national study found that there was a positive association between COVID-19 incidence and long-term exposure to fine particulate matter (PM_2.5) in Canadian health regions. The association was larger in magnitude and stronger in health regions with higher rates of COVID-19, and in those health regions where estimated exposure to PM_2.5 is expected to be more accurate. The Toronto study found that there was a positive association between COVID-19 incidence and long-term exposure to reactive oxygen species in PM_2.5. The results require further examination using studies based on individual-level rather than area-level data.

  Publications: Stieb, D.M., Evans, G.J, To, T.M., Brook, J.R., Burnett, R.T. 2020. An ecological analysis of long-term exposure to PM_2.5 and incidence of COVID-19 in Canadian health regions. Environ Res. 2020 Dec;191:110052. DOI: 10.1016/j.envres.2020.110052.

  Stieb, D.M., Evans, G.J., To, T.M., Lakey, P.S.J., Shiraiwa, M., Hatzopoulou, M., Minet, L., Brook, J.R., Burnett, R.T., Weichenthal, S.A. 2021. Within-city Variation in Reactive Oxygen Species from Fine Particle Air Pollution and COVID-19. Am J Respir Crit Care Med. 2021 Apr 2. DOI: 10.1164/rccm.202011-4142OC.

7.3 Water quality

ECCC continued water quality research activities during 2020-2021.

7.3.1 ECCC research

• Nonylphenol, octylphenol, and nonylphenol ethoxylates dissemination in the Canadian freshwater environment

  Focus of research: Nonylphenol, octylphenol, and nonylphenol ethoxylates are manmade compounds that are only discharged in the environment due to anthropogenic activities. The objectives of this study were to determine the current concentrations of these substances in the Canadian freshwater environment and to determine if past regulatory actions were beneficial to the environment.

  Results: All compounds in the study were detected more frequently in urban and municipal wastewater treatment plant-associated sites than at other locations. Additionally, there is a statistically significant (p lesser than 0.05) downward temporal trend in 4-nonylphenols concentrations in Canadian surface waters from 2014 to 2019. There were no exceedances of the Canadian Water Quality Guideline of 1000 ng/L.

  Publication: Lalonde, B., Garron, C. 2021. Nonylphenol, Octylphenol, and Nonylphenol Ethoxylates Dissemination in the Canadian Freshwater Environment. Arch Environ Contam Toxicol 80, 319–330. https://doi.org/10.1007/s00244-020-00807-x.

• Aquatic toxicology of silver nanoparticles

  Focus of research: Silver nanoparticles (nAg) represent one of the most popular nanomaterials owing to their antibacterial properties. The increased use of nAg has raised concerns on potential impacts to aquatic ecosystems. The influence of surface coatings, size and the form of silver nanoparticles on the bioavailability and toxicity in freshwater mussels were examined.

  Results: Different geometries of nanosilver initiated biophysical stress in the soft tissues of mussels, leading to the formation of liquid crystals, and protein damage. Moreover, the toxicity of nanometals were influenced by the properties of surface waters (for example, conductivity and organic content) and had different toxicity than did dissolved metals.

  Publications: Auclair, J., Peyrot, C., Wilkinson, KJ, Gagné, F. 2020. The geometry of silver nanoparticles toxicity in freshwater mussels. Comp Biochem Physiol 239, 108841

  Auclair, J., Turcotte, P., Gagnon, C., Gagné, F. 2021. The influence of surface waters on the bioavailability and toxicity of copper oxide nanoparticles to freshwater mussels. Invertebrate Survival Journal, 2021, 18(1), pp. 33–45.

  Auclair, J., Turcotte, P., Gagnon, C., Peyrot, C., Wilkinson, K.J., Gagné, F. 2020. Toxicological effects of inorganic nanoparticle mixtures in freshwater mussels. Environments - MDPI, 7(12), pp. 1-18.

  Auclair J., Turcotte P., Gagnon C., Peyrot C., Wilkinson K.J., and Gagné, F., 2020. Comparative toxicity of copper oxide nanoparticles and dissolved copper to freshwater mussels. Intern. J. Zool. Invest. 6: 135-147. https://doi.org/10.33745/ijzi.2020.v06i01.011.

  Auclair, J., Turcotte, P., Gagnon, C., Gagné, F. 2020. Toxicity of copper oxide nanoparticles to rainbow trout juveniles. Current Topics in Toxicology 16, pp. 1–11.

  André, C., Lachance, B., Turcotte, P., Gagnon, C., Emond, C. 2020. Size-dependent toxicity of CdTe quantum dot aggregates in trout and human hepatocytes. Current Topics in Toxicology 16, 215–225.

  Gagné, F. 2020. Mini-review: Ecotoxicology of altered fractal organization in cells. Am J Biomed Sci Res 8, 498-492.

• Availability and biophysical effects of polystyrene nanoparticles

  Focus of research: The presence of nanoplastics in various products and from the weathering of released plastic materials are of concern for the environment’s safety. The purpose of this study was to examine the biophysical effects of polystyrene nanoparticles on cnidarian and freshwater mussels.

  Results: Polystyrene nanoplastics in intercellular spaces were found to influence lactate dehydrogenase activities in Hydra attenuate. They disrupted the internal organization of cells in a way that interfered with the normal association of enzymes involved in energy metabolism in freshwater mussels, potentially increasing oxidative stress in affected organisms.

  Publications: Auclair, J., Gagné, F. 2020. Crowding Effects of Polystyrene Nanoparticles on Lactate Dehydrogenase Activity in Hydra attenuata. J Xenobiotics 10, 2–9.

  Auclair, J., Peyrot, C., Wilkinson, K.J., Gagné, F. 2020. Biophysical effects of polystyrene nanoparticles on Elliptio complanata mussels. Environ Sci Poll Res. https://doi.org/10.1007/s11356-020-08920-.

  Auclair, J., Gagné, F. 2020. Change in the spatial organization of mussel mitochondria exposed to polystyrene nanoplastics. Current Topics in Toxicology,16, 127–140.

  Auclair, J., Gagné, F. 2020. The influence of polystyrene nanoparticles on enzyme clusters of fumarate, malate dehydrogenase and citrate synthase: a fractal analysis study. Letters in Applied NanoBioScience 9, 981– 987.

  Auclair, J., Quinn, B. and Gagné, F. 2020. Bioavailability and Effects of Polystyrene Nanoparticles in Hydra circumcincta. Emerging Technologies and Research for Eco-friendly Aquaculture Chapter 2-14

  Auclair, J., Gagné, F. 2020. The influence of polystyrene nanoparticles on the fractal kinetics of lactate dehydrogenase. Biochemistry and Biophysics Reports 23, 100793

• Fate, transformation and bioavailability of metal-based nanoparticles in the aquatic environment

  Focus of research: To evaluate the environmental transformation and fate of metal-based nanomaterials in natural waters. The fate of nanomaterials such as cerium, copper and zinc oxides and silver nanoparticles (NPs) released from municipal wastewaters and their toxicity in exposed fish and bivalves were assessed.

  Results: Analytical issues related to interferences from naturally occurring colloidal zirconium were attenuated by the use of the 109 isotope in detecting silver, limiting false positives and improving the reliability of silver nanoparticle measurements in natural waters. Moreover, the cytotoxicity of monomeric and aggregated cadmium telluride quantum dots (CdTe QD) in human hepatoma (HepG2) were compared to rainbow trout hepatocytes (RTH). CdTe QDs were cytotoxic to both cell types with toxicity decreasing as QD aggregate size increased.

  Publications: André, C., Lachance, B., Turcotte, P., Gagné, F., Gagnon, C., Emond, C. 2020. Size-dependent toxicity of CdTe quantum dot aggregates in trout and human hepatocytes. Current Topics Toxicol. 16: 215 - 225.

  Turcotte, P., Gagnon, C. 2020. Zirconium interferences on the detection of silver nanoparticles by single particle ICP-MS: implications on natural water analysis. J Nanomed Nanotech. 11:550. DOI: 10.35248/2157-7439.20.11.550.

• Accumulation, trophic transfer and biological effects of priority perfluoroalkyl substances (PFAS) in aquatic environments

  Focus of Research: This research project aims to better understand the environmental distribution of emerging perfluoroalkyl substances in aquatic environments and their biological effects in aquatic organisms. Perfluoroalkyl substances (PFAS) are a group of man-made chemicals that have been used since the 1950s in a wide range of consumer products and in firefighting foams.

  Results: A review article summarizes discussions concerning the ecotoxicology and ecological risks of PFAS. It includes information relevant to problem formulation/ prioritization, exposure, and hazard/effects of PFAS in the context of regulatory and ecological risk assessment activities from around the world. In a separate study, the temporal trends of legacy and unregulated PFASs in liver of the endangered beluga whale population from the St. Lawrence Estuary in Canada collected from 2000 to 2017 were examined. A suite of 54 PFASs were tentatively identified, and were grouped into nine structurally distinct classes. Single-hydrogenated perfluoro carboxylic acids (H-PFCAs), single-hydrogenated sulfonamides (H-Sulfonamides), as well as other select sulfonamides were detected for the first time in wildlife. Greater concentrations of the majority of PFASs were determined in newborns and juveniles than in adults, suggesting effective placental and lactational transfer of PFASs.

  Publications: Ankley, G.T., Cureton, P., Hoke, R.A., Houde, M., Kumar, A., Kurias, J., Lanno, R., McCarthy, C., Newsted, J., Salice, C.J., Sample, B.E., Sepulveda, M.A., Steevens, J., Valsecchi, S. 2020. Assessing the ecological risks of per- and polyfluoroalkyl substances: Current state-of-the science and a proposed path forward. Environmental Toxicology and Chemistry. 40: 564-605. Critical review. Open Access. https://doi.org/10.1002/etc.4869.

  Barrett, H., Dua, X., Houde, M., Lair, S., Verreault, J., Peng, H. 2021. Suspect and nontarget screening revealed class-specific temporal trends (2000-2017) of poly- and perfluoroalkyl substances in beluga whales (Delphinapterus leucas). Environmental Science and Technology 55: 1659-1671. https://doi.org/10.1021/acs.est.0c05957.

  Giraudo, M., Colson, T.-L.L., De Silva, A.O., Lu, Z., Gagnon, P., Brown, L., Houde, M. 2020. Food-borne exposure of juvenile rainbow trout (Oncorhynchus mykiss) to benzotriazole UV stabilizers alone and in mixture induces specific transcriptional changes. Environmental Toxicology and Chemistry 39: 852-862. https://doi.org/10.1002/etc.4676.