Canadian Environmental Protection Act, 1999
Annual Report to Parliament for April 2019 to March 2020: chapter 7
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- 7. Report on research
7. Report on research
Environment and Climate Change Canada (ECCC) and Health Canada (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 2019-2020.
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
In addition, HC undertakes research to support the development of regulations, guidelines and air quality objectives with the goal of reducing population exposures to pollutants and improving human health.
During 2019-2020, 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 Action Plan.
In 2019-2020, 19 new CMP research projects were initiated at ECCC. Although these projects are only expected to be completed in March 2021, they have produced preliminary results and have led to the publication of over 40 journal articles addressing a range of topics related to CMP priority substances, including sources, fate, mode of action, hazard, as well as standard methods development. References to a selection of these articles are provided below as examples.
Chemicals in the atmosphere
Sources and mechanisms of the transport and deposition of mercury
Focus of research: Investigation of the sources and mechanisms of the transport and deposition of mercury from the atmosphere to the surface.
Results: Atmospheric Hg dry deposition through vegetation uptake is the primary source of mercury in surface soil. This in turn suggests that climate change will have a significant impact on the cycling of mercury in the environment, as it influences vegetative development. Also, chemical reactions of bromine atoms enhance deposition of mercury from the atmosphere to the surface.
Publications: St Louis, V.L., Graydon, J.A., Lehnherr, I., Amos, H.M., Sunderland, E.M., St Pierre, K.A., Emmerton, C.A., Sandilands, K., Tate, M., Steffen, A., Humphreys, E.R., Atmospheric Concentrations and Wet/Dry Loadings of Mercury at the Remote Experimental Lakes Area, Northwestern Ontario, Canada, Environmental Science and Technology, 2019, 53, 14, 8017-8026, 10.1021/acs.est.9b01338.
Wang, X., Yuan, W., Lin, C.-J., Zhang, L., Zhang, H., Feng, X., Climate and Vegetation as Primary Drivers for Global Mercury Storage in Surface Soil, Environ. Sci. Technol. 2019, 53, 18, 10665-10675, 10.1021/acs.est.9b02386.
Wang, S., McNamara, S.M., Moore, C.W., Obrist, D., Steffen, A., Shepson, P.B., Staebler, R.M., Raso, A.R.W., Pratt, K.A., Direct detection of atmospheric atomic bromine leading to mercury and ozone depletion, Proceedings of the National Academy of Sciences of the United States of America, Volume 116, Issue 29, July 2019, 14479-14484, 10.1073/pnas.1900613116.
Polycyclic aromatic compounds in urban air
Focus of research: Passive air sampling in Toronto and the Greater Toronto Area from 2016 to 2017 was used to investigate ambient levels of polycyclic aromatic compounds (PACs) associated with different source types.
Results: Traffic emission was a major contributor to PACs in the atmosphere of Toronto. This study highlights the importance of traffic as an emission source of PACs to urban air and the relevance of PAC classes other than just unsubstituted PAHs that are important but currently not included in air quality guidelines or for assessing inhalation cancer risks.
Publication: Jariyasopit, N., Tung, P., Su, K., Halappanavar, S., Evans, G.J., Su, Y., Khoomrung, S., Harner, T., Polycyclic aromatic compounds in urban air and associated inhalation cancer risks: A case study targeting distinct source sectors, Environmental Pollution, Volume 252, September 2019, 1882-1891, 10.1016/j.envpol.2019.06.015.
Chemicals in the Arctic
Prevalence, transport, fate and behavior of certain toxic substance families in the Arctic
Focus of research: Understanding the prevalence, transport, fate and behavior of certain toxic substance families.
Results: Hexachlorobutadiene (HCBD) has been measured in Arctic air collected from monitoring stations in Finland and Canada. PAHs in the Canadian and Norwegian Arctic are likely to have originated in the northern hemisphere - predominantly from Western Russia, northern Europe, and North America.
Publications: Balmer, J.E., Hung, H., Yu, Y., Letcher, R.J., Muir, D.C.G., Sources and environmental fate of pyrogenic polycyclic aromatic hydrocarbons (PAHs) in the Arctic, Emerging Contaminants, Volume 5, 2019, 128-142, 10.1016/j.emcon.2019.04.002.
Balmer, J.E., Hung, H., Vorkamp, K., Letcher, R.J., Muir, D.C.G., Hexachlorobutadiene (HCBD) contamination in the Arctic environment: A review, Emerging Contaminants, Volume 5, 2019, 116-122, 10.1016/j.emcon.2019.03.002.
Muir, D., Bossi, R., Carlsson, P., Evans, M., De Silva, A., Halsall, C., Rauert, C., Herzke, D., Hung, H., Letcher, R., Rigét, F., Roos, A., Levels and trends of poly- and perfluoroalkyl substances in the Arctic environment - An update, Emerging Contaminants, 5, 2019, 240-271, doi.org/10.1016/j.emcon.2019.06.002.
Perfluoroalkyl substances and organophosphate ester flame retardants in the high Arctic
Focus of research: To discern the sources and transport of PFAS to remote freshwater ecosystems in the High Arctic and To investigate the distribution of 14 OPEs in a High Arctic aquatic ecosystem and to explore the input and outputs of OPEs from glacial rivers to a large lake.
Results: Annual atmospheric deposition is a major source of PFAS that undergo complex cycling in the High Arctic. Perfluoroalkyl carboxylic acids (PFCA) in snowpacks display odd-even concentration ratios characteristic of long-range atmospheric transport and oxidation of volatile precursors. This study highlights long-range transport of OPEs, their deposition in Arctic glaciers, landscapes, and lakes.
Publications: MacInnis, J.J., Lehnherr, I., Muir, D.C.G., St. Pierre, K.A., St. Louis, V.L., Spencer, C., De Silva, A.O.ǂ 2019. Fate and Transport of Perfluoroalkyl Substances from Snowpacks into a Lake in the High Arctic of Canada. Environ. Sci. Technol. 53: 10753-10762.
Sun, Y., De Silva, A.O., St. Pierre, K.A., Muir, D.C.G., Spencer, C., Lehnherr, I., MacInnis, J.J. 2020. Glacial Melt Inputs of Organophosphate Ester Flame Retardants to the Largest High Arctic Lake, Environ. Sci. Technol. 2020, 54: 2734-2743.
Atmospheric transport pathways for microplastics
Focus of research: To determine the extent of sources and atmospheric transport pathways for microplastics, particularly as related to impacts in the Arctic.
Results: Microplastics were found across the studied marine systems of the eastern Canadian Arctic and Hudson Bay, and it was concluded that microplastics likely undergo long-range transport via oceanic and air currents, and via riverine systems to reach the Arctic, as well as coming from local sources.
Publication: Adams, J., Jantunen, L., Diamond, M. L., Finkelstein, S. A., Rochman, C. M., Bernstein, S., Stern, G., Understanding sources and transport of microplastic pollution to the Canadian Arctic, Conference paper, SETAC Europe, Helsinki Finland, May 2019.
Exposure of workers at e-waste dismantling facilities to flame retardant chemicals
Focus of research: Levels and exposure of workers to flame retardant chemicals at Canadian e-waste dismantling facilities.
Results: Levels of some flame retardants were found to be 1 to 2 orders-of-magnitude higher than in residential homes, and some air and dust concentrations as well as some estimated exposures exceeded those from informal e-waste facilities located in low and middle income countries.
Publications: Stubbings, W.A., Nguyen, L.V., Romanak, K., Jantunen, L., Melymuk, L., Arrandale, V., Diamond, M.L., Venier, M., Flame retardants and plasticizers in a Canadian waste electrical and electronic equipment (WEEE) dismantling facility, Science of the Total Environment, Volume 675, July 2019, 594-603, 10.1016/j.scitotenv.2019.04.265.
Nguyen, L.V., Diamond, M.L., Venier, M., Stubbings, W.A., Romanak, K., Bajard, L., Melymuk, L., Jantunen, L.M., Arrandale, V.H., (2019), Exposure of Canadian electronic waste dismantlers to flame retardants, Environment International, 95-104, 10.1016/j.envint.2019.04.056
A novel group of persistent chemicals; liquid crystal monomers
Focus of research: The cytotoxic and transcriptomic effects of a novel group of persistent chemicals, liquid crystal monomers (LCM), were determined. These substances are found in liquid crystal display screens including TVs, personal computers and most importantly, cell phones.
Results: Following exposure to mixtures of LCM collected from 6 LCD devices, significant modulation of 5 genes, CYP1A4, PDK4, FGF19, LBFABP, and THRSP, was observed in vitro. LCMs were detectable in 47% of analyzed indoor dust samples,
Publication: Su, H., Shi, S., Zhu, M., Crump, D., Giesy, J.P., Letcher, R.J., Su, G. 2019. Persistent, Bioaccumulative and Toxic Properties of Liquid Crystal Monomers (LCMs) and their Detection in Indoor Residential Dust. Proc. Nat. Acad. Sci 116(52): 26450-26458.
Acute Transcriptomic Dose-Response Analysis in Adults Fish and Fish Embryos for BPA, DEHP and Related Compounds
Focus of research: Resource limitations often require risk assessors to extrapolate chronic toxicity from acute tests using assessment factors. Transcriptomic dose-response analysis following short-term exposures may provide a more reliable and biologically-based alternative for estimating chronic toxicity. This study applies cutting edge genomics techniques to estimate concentrations that can cause low-dose long-term toxicity in fish exposed to estrogenic chemicals (bisphenol A (BPA), diethylhexylphthalate (DEHP), and several proposed BPA- and DEHP-replacement compounds).
Results: Using genomics in adult fish following short-term exposure to BPA-related compounds, doses that would cause low-dose long-term toxicity were estimated (i.e. the point-of-departure, POD). The genomics-based PODs were highly correlated to and protective of (i.e. within 10-fold) PODs determined using traditional methods. A meta-analysis of genomics data in a multi-species study also found that a genomics-based POD was highly correlated to a traditionally determined POD.
Publications: Pagé-Larivière F, Crump D, O'Brien J. 2019. Transcriptomic points-of-departure from short-term exposure studies are protective of chronic effects for fish exposed to estrogenic chemicals. Toxicology and Applied Pharmacology. 378: 114634.
New method for studying metabolism of triphenyl phosphate (TPHP) in biota
Focus of research: TPHP has been detected in a wide range of environmental samples, especially in indoor dust samples and may have possible health effects. This study investigated the metabolism of the flame retardant and plasticizer chemical, triphenyl phosphate (TPHP), in a rat liver microsome-based in vitro assay with glutathione (GSH) in order to elucidate metabolic pathways leading to formation of conjugates.
Results: A highly sensitive and efficient method developed for the detection and characterization of GSH reactive metabolites revealed that certain GSH conjugates may be valuable candidate biomarkers for monitoring TPHP exposure in biota.
Publication: Chu, S.-G., Letcher , R.J. 2019. In vitro metabolic activation of triphenyl phosphate leading to the formation of glutathione conjugates by rat liver microsomes. Chemosphere 237: 124474. DOI: 10.1016/j.chemosphere.2019.124474
Chemicals in wildlife
Distribution of halogenated flame retardants in herring gull tissue and eggs
Focus of research: Polybrominated diphenyl ethers (PBDEs) and other halogenated flame retardants (HFRs) continue to be an environmental concern. This study examined the distribution of HFRs within the tissues and eggs of an upper trophic level Great Lakes species, the herring gull.
Results: Among the 25 PBDEs and 23 non-PBDE HFRs assessed, only 6 BDE congeners, hexabromocyclododecane (HBCDD), and Dechlorane Plus (syn- and anti-DDC-CO) were frequently detectable and quantifiable. Maternal transfer rates of PBDEs and non-PBDE HFRs were low (~4.7 and ~2.9 % respectively), suggesting that in ovo transfer is not a significant mode of depuration for these compounds.
Publication: Smythe, S.A., Mattioli, L.C., Letcher, R.J. 2020. Distribution behaviour in body compartments and in ovo transfer of flame retardants in North American Great Lakes herring gulls (Larus argentatus). Environ. Pollut. 262: 114306. DOI: 10.1016/j.envpol.2020.114306
Trends of novel flame retardants in herring gull eggs in the Great Lakes
Focus of research: The occurrence of the environmentally novel tetrabromobisphenol-A-bis(2,3,-dibromopropyl ether) (TBBPA-BDBPE) flame retardant contaminant is generally unknown in wildlife. We developed a highly sensitive method of detection and report on temporal and spatial trends in herring gull eggs across the Laurentian Great Lakes of North America.
Results: Typical of many alternate flame retardants in wildlife, TBBPA-BDBPE levels in the gull samples were low with a few high values and increasing prevalence through time. They appear to be associated with terrestrial versus aquatic food sources.
Publication: Gauthier, L.T., Laurich, B., Hebert, C.E., Drake, C., Letcher, R.J. 2019. Tetrabromobisphenol-A-bis (dibromopropyl ether) flame retardant in eggs, regurgitates and feces of herring gulls (Larus argentatus) from multiple North American Great Lakes locations. Environ. Sci. Technol. 53: 9564-9571. DOI: 10.1021/acs.est.9b02472
Bioaccumulation and biomagnification of PFAS in liver tissues of polar bear and ringed seals
Focus of research: The objective of the present study was to investigate the prey to predator relationships of per-/poly-fluoroalkyl substance (PFAS) bioaccumulation and biomagnification of established and newer perfluorinated sulfonate (PFSA) and perfluorinated carboxylic acid (PFCA) contaminants, and several important PFSA precursors in blubber and liver tissues of polar bears and ringed seals.
Results: The bioaccumulation and biomagnification of 22 major PFAS were investigated in tissues of polar bears and their major prey species, the ringed seal. In both polar bears and seals, concentrations of PFSAs in liver were much higher than in fat. There were differences in distribution of short and long chain PFCAs between liver and fat in both species. Biomagnification factors (which indicate the accumulation of contaminants from prey to predator) from seal blubber to bear liver best reflect the dietary exposure relationship of PFAS between bears and seals.
Publication: Boisvert, G., Sonne, C., Rigét, F.F., Dietz, R., Letcher, R.J., 2019. Bioccumulation and biomagnification of perfluoroalkyl acids and major precursors in East Greenland polar bears and their ringed seal prey. Environ. Pollut. 252: 1335-1343. DOI: 10.1016/j.envpol.2019.06.035
Priority Perfluroalkyl Substances and Wildlife: 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. This research was done to support work under the CMP and the Stockholm Convention.
Results: Several perfluoroalkyl acids and sulfonamides (PFAAs) were found in the majority of peregrine falcon eggs and nestlings across the Laurentian Great Lakes Basin. The shorter-chain perfluorinated carboxylic acids (PFCAs) were dominant in nestling plasma and the longer-chain ones in eggs. Egg concentrations of PFCAs and perfluorinated sulfonic acids were related to maternal foraging locations, whereas concentrations in nestling blood were related to the trophic position of prey in the nestlings’ diet. Results suggested that compared to rural nestling peregrines, urban nestlings may be exposed to higher PFCAs and prone to their potential physiological impacts given their poorer body condition. Preliminary investigations with tree swallows suggest that PFAAs and microfibers are nearly ubiquitous for these birds in this region.
Publications: Fremlin, K., J. Elliott, D. Green, K. Drouillard, T. Harner, A. Eng, and F. Gobas. 2020. Trophic magnification of legacy persistent organic pollutants in an urban terrestrial food web. Science of the Total Environment. 714:137646. https://doi.org/10.1016/j.scitotenv.2020.136746
Marteinson, S.C, Guigueno, M.F., Fernie, K.J., Head, J.A., Chu, S., Letcher, R.J. 2020. Uptake, deposition and metabolism of triphenyl phosphate in embryonated eggs and chicks of Japanese quail (Cortunix japonica). Environ. Toxicol. Chem. 39: 565-573. https://doi.org/10.1002/etc.4637
Guigueno, M.F., Head, J.A., Letcher, R.J., Karouna-Renier, N., Peters, L., Hanas, A.M., Fernie, K.J. 2019. Early life exposure to triphenyl phosphate affects thyroid function, growth, and resting metabolic rate, of Japanese quail (Coturnix japonica) chicks. Environ. Poll. 253:899-908. https://doi.org/10.1016/j.envpol.2019.05.110
Exposure of rainbow trout to benzotriazole UV stabilizers
Focus of research: Benzotriazole ultraviolet-stabilizers (BZT-UVs) are commonly used as additives to protect from light-induced degradation in a variety of consumer goods. Despite their widespread presence in aquatic ecosystems, information on the effects of these compounds remains largely unknown.
Results: Individual compounds induced specific transcriptional changes and revealed potentially distinct modes of action; UV-328 impacted immune response-related genes, and UV-234 affected genes involved in glucose and cholesterol metabolism; both compounds regulated iron homeostasis genes in opposite ways. The mixture of both BZT-UVs did not produce significant evidence of additive or synergistic effects.
Publication: 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
Chemicals in wastewater
Concentrations of ScotchgardTM derived side-chain fluorinated polymer surfactants in biosolids generated from Canadian wastewater treatment plants
Focus of research: To determine if ScotchgardTM derived side-chain fluorinated polymer components found in soil were derived from biosolids that were land-applied. The objectives of the study were to: 1) assess the occurrence of these Scotchgard derived side-chain fluorinated polymer surfactants in biosolids generated from Canadian wastewater treatment plants (WWTPs), and 2) examine the relationships between the locations and the type of WWTP processes and the levels of these side-chain polymer components in biosolids.
Results: High concentrations of the main components in Scotchgard fabric protector products (pre-2002 and post-2002; side-chain fluorinated polymer surfactants, S1 and S2, respectively) were detected in biosolids samples from 20 pan-Canadian WWTPs. S1 concentrations and S2 concentrations were much higher than that of other commonly monitored perfluoroalkyl substances (PFAS). A negative linear correlation was observed between concentrations of S1 (or S2) with the volume of WWTP treated wastewater per day per person (m3/person/day). The total concentrations of 22 other PFAS were approximately 30 times lower than S1 and S2 concentrations. PFAS concentrations in biosolids are likely underestimated without consideration of S1 and S2.
Publication: Letcher, R.J., Chu, S.-G., Smyth, S.A. 2020. Side-chain fluorinated polymer surfactants in biosolids from wastewater treatment plants. J. Hazard. Mat. 388: 122044. DOI: 10.1016/j.jhazmat.2020.122044
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 soil invertebrate species and indigenous microorganisms in agricultural soil were examined, with and without biosolid amendment. This also included an evaluation of the bioaccumulation potential in earthworms over time at sublethal levels.
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; plant growth; and soil invertebrate health and reproduction. The research demonstrated the utility of alternate metrics used to measure bioavailability and toxicity.
Publications: Samarajeewa, A.D., Velicogna, J.R., Schwertfeger, D.M., Jesmer, A.H., Subasinghe, R.M., Princz, J.I., Scroggins, R.P., Beaudette, L.A. 2019. Effect of silver nanoparticle contaminated biosolids on the soil microbial community. NanoImpact 14:100157.
Velicogna, J., Schwertfeger, D., Beer, C., Jesmer, A., Kuo, J., Chen, H., Scroggins, R., Princz, J. 2019. Phytotoxicity of copper oxide nanoparticles in soil with and without biosolid amendment. Nanoimpact 17:100196.
Understanding the atmospheric fate and toxicity of engineered nanoparticles through transformation studies
Focus of research: This research investigated the chemical and toxicity changes occurring in engineered nanoparticles when exposed to the atmosphere. Testing was conducted on the impacts of various atmospheric coatings on the oxidative potential of engineered nanoparticles.
Results: The health risk of airborne nanoparticles is strongly related to the length of time they undergo atmospheric chemical reaction, and accounting for the impacts of atmospheric processing should be considered critical for making accurate risk assessments.
Publication: Liu, Q, Shahpoury, P, Liggio, J, Harner, T, Li, K, Lee, P, Li, SM. 2019. Understanding the Key Role of Atmospheric Processing in Determining the Oxidative Potential of Airborne Engineered Nanoparticles. Environmental Science and Technology Letters, 7 (1), pp. 7-13. DOI: 10.1021/acs.estlett.9b00700
HC funded 31 CMP research projects in 2019-2020. 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, hazard characterization and identification of biotechnology microbes.
In vitro to in vivo extrapolation (IVIVE) toxicokinetics of CMP chemicals
Focus of research: The goal of this research was to develop better in-vitro toxicokinetic (TK) data and consistent biological extrapolation models to predict realistic doses in-vivo where potential toxicological effects would be anticipated based on measures from high throughput in-vitro assay toxicity databases. Tests and models focus on substances recently used as replacements for plasticizers, flame retardants and perfluorinated chemicals.
Results: The project resulted in the development of a new software platform to screen and model high throughput screening (HTS) data. The platform, named DREAM-TK, allows data users to analyze and visualize HTS toxicity and in-vitro TK data. The collected in vitro data was sorted and treated before being compiled for model predictions of daily dose exposure values. An application of the approach using a fire retardant (hexabromocycldodecane) in vitro data was presented in a publication. This tool helps in identifying chemicals considered safe and/or to trigger additional testing.
Publication: Moreau M, Nong A. Evaluating hexabromocyclododecane (HBCD) toxicokinetics in humans and rodents by physiologically based pharmacokinetic modeling. Food Chem Toxicol. 2019 Nov;133:110785. doi: 10.1016/j.fct.2019.110785.
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) identify and characterize the molecular target(s) mediating toxicity of organophosphate flame retardants and 2) establish methods to screen for molecules that impair thyroid hormone signaling.
Results: Enzyme targets of flame retardant toxicity were identified in all affected organs. Detailed structure activity studies of enzyme inhibition have been completed for liver target and for human homolog enzyme. 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 and to set priorities for further assessment.
Publications: Hongyan Dong, Marlena Godlewska and Michael G. Wade. A Rapid Assay of Human Thyroid Peroxidase Activity. 2020. Toxicol In Vitro. 2019 Oct 16;62:104662. DOI: 10.1016/j.tiv.2019.104662
Wade MG, Kawata A, Rigden M, Caldwell D, Holloway AC. 2019. Toxicity of Flame Retardant Isopropylated Triphenyl Phosphate: Liver, Adrenal, and Metabolic Effects. Int J Toxicol. 2019 May 27:1091581819851502. DOI: 10.1177/1091581819851502
Dong H, Atlas E, Wade MG. 2019. Development of a non-radioactive screening assay to detect chemicals disrupting the human sodium iodide symporter activity. Toxicol. In Vitro. 57:39-47. doi: 10.1016/j.tiv.2019.01.021
Gouesse R, Lavoie M, Dianati E, Wade M, Hales B, Robaire B, Plante I. 2019. Gestational and Lactational Exposure to an Environmentally-relevant Mixture of Brominated Flame Retardants Down-regulates Junctional Proteins, Thyroid Hormone Receptor a1 Expression and the Proliferation- Apoptosis Balance in Mammary Glands Post Puberty. Toxicol Sci.171(1) 13-31. DOI: 10.1093/toxsci/kfz147
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, in part via the secretion of molecules called adipokines. 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, such as diabetes, and to investigate the effects of chemicals on the initiation and progression of endocrine cancers such as breast cancer.
Results: Data suggests that bisphenol-A analogs, such as bisphenol S, can act as endocrine disruptor chemicals and affect the mammary gland. The data also suggests that flame-retardants i.e. dechlorane plus, and polychlorinated biphenyls can also act as metabolic disruptors.
Publications: Atlas E, Dimitrova V. 2019. Bisphenol S and Bisphenol A disrupt morphogenesis of MCF-12A human mammary epithelial cells. Sci Rep. doi: 10.1038/s41598-019-52505-x.
Tremblay-Laganière C, Garneau L, Mauger JF, Peshdary V, Atlas E, Nikolla AS, Chapados NA, Aguer C. 2019 Polychlorinated biphenyl 126 exposure in rats alters skeletal muscle mitochondrial function. Environ Sci Pollut Res Int. doi: 10.1007/s11356-018-3738-8.
Peshdary V, Calzadilla G, Landry A, Sorisky A, Atlas E. 2019 Dechlorane Plus increases adipogenesis in 3T3-L1 and human primary preadipocytes independent of peroxisome proliferator-activated receptor γ transcriptional activity. Int J Obes (Lond). 43(3):545-555. doi: 10.1038/s41366-018-0072-7.
GeneTox21 - An integrated, high-throughput (HT) platform for In Vitro genetic toxicity assessment of new and existing chemicals
Focus of research: Genetic damage is associated with numerous human diseases. Chemical screening programs routinely assess a chemical’s ability to damage genetic material (i.e., genetic toxicity). Traditional assessment tools (i.e., bioassays) are laborious and not conducive to high-throughput (HT), high-content chemical screening using tools that employ cultured cells (i.e., in vitro bioassays). This project is developing a NAM (New Approach Methodology) comprised of an integrated, multi-assay, high(er) throughput (HT) platform for the assessment of chemically-induced genetic toxicity. The HT platform, which is called GeneTox21, will be internationally promoted to encourage its adoption for robust genetic toxicity assessment of new and existing substances.
Results: Progress to date 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. For the former, a miniaturized protocol was developed to rapidly assess the effects of various treatment times and post-exposure sampling times. The results obtained includes multi-assay assessments of numerous reference compounds, and numerous data-poor priority substances. 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: Cox, J.A., Zwart, E., Luijten, M. 2019. The development and pre-validation of an in vitro mutagenicity assay based on MutaMouse primary hepatocytes, Part II: Assay performance for the identification of mutagenic chemicals. Environmental and Molecular Mutagenesis. 60:348-360
Cox, J.A. and P.A. White. 2019. The mutagenic activity of select azo compounds in MutaMouse target tissues in vivo and primary hepatocytes in vitro. Mutation Research. 844:25-34.
Tran, YK, Juick, JK, Keir, JLA, Williams, A, Swartz, CD, Recio, L, White, PA, Lambert, IB and CL Yauk. 2019. Integrated in silico and in vitro genotoxicity assessment of thirteen data-poor substances. Reg Toxicol Pharm. 107:104427
Madia, F, Kirkland, D, Morita, T, White, PA Asturiol, D and R Corvi. 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.
Refining and deploying a quantitative framework for the analysis and regulatory interpretation of genetic toxicity dose-response data
Focus of research: This project is using data collected from the scientific literature to improve the scientific foundation for quantitative use of genetic toxicity dose-response data for risk assessment and regulatory decision-making. More specifically, the work is determining the levels of genotoxic effects (for example, genetic mutations) that should be considered adverse, and refining the uncertainty factor values required for determination of human exposure limit values, for example, Tolerable Daily Intake.
Results: A formal context was developed to justify quantitative interpretation of genetic toxicity dose-response data for regulatory decision-making. Published dose-response data were collected and curated; ongoing analyses is determining the response level that should be considered as an adverse health effect. Additional analyses of information published in the scientific literature is being used to establish the uncertainty factors required to extrapolate from experimental animal data, i.e., animal-to-human inter-species adjustment and adjustment for variability in human sensitivity. The results obtained are being applied to case studies of genotoxic chemicals of concern (for example, alkylnitrosamines and benzene). Collectively, the results obtained are being used to develop a formal framework for quantitative use of genetic toxicity data for regulatory evaluations of new and existing chemicals.
Publications: Heflich, RH, Johnson, GE, Zeller, A, Marchetti, F, Douglas, GR, Witt, KL, Gollapudi, BB and PA White. 2019. Mutation as a toxicological endpoint for regulatory decision-making, Environmental and Molecular Mutagenesis 61:34-41. https://doi.org/10.1002/em.22338
Luijten, M, Ball, NS, Dearfield, KL, Gollapudi, BB, Johnson, GE, Madia, F, Pfuhler, S, Settivari, RS, ter Burg, W, van Benthem, J and PA White. 2020. Utility of a next generation framework for assessment of genomic damage: a case study using the industrial chemical benzene. Environmental and Molecular Mutagenesis 61:94-113. doi: 10.1002/em.22346
White, PA, Long, AS and GE Johnson. 2020. Quantitative Interpretation of Genetic Toxicity Dose-Response Data for Risk Assessment and Regulatory Decision-Making: Current Status and Emerging Priorities. Environ Molec Mutagen, 61:66-83.
An integrated testing strategy to assess 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 have been used by the Organisation for Economic Cooperation and Development (OECD) to update the recommended experimental design in 1 test guideline that is routinely used to assess the ability of chemicals to induce mutations (i.e., changes in the sequence of the DNA).
Publications: Heflich HR, Johnson GE, Zeller A, Marchetti F, Douglas GR, Witt KL, Gollapudi BB, White PA (2020) Mutation as a toxicological endpoint for regulatory decision-making. Environmental and Molecular Mutagenesis, 61:34-41. Epub: October 10, 2019
Marchetti F, Douglas GR, Yauk CL (2020) A return to the origin of the EMGS: rejuvenating the quest for human germ cell mutagens and determining the risk to future generations. Environmental and Molecular Mutagenesis, 61:42-54. Epub: August 31, 2019.
Godschalk RWL, Yauk CL, van Benthem J, Douglas GR, Marchetti F (2020) In utero exposure to genotoxins leading to genetic mosaicism: an overlooked window of susceptibility in genetic toxicology testing? Environmental and Molecular Mutagenesis. 61:55-65. Epub: November 19, 2019.
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 new approach methodologies (NAM) to effectively leverage and integrate existing and emerging data.
Results: In 2019-2020, 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: Paul Friedman K., Gagne M., Loo, L-H., Karamertzanis, P., Netzeva, T., Sobanski, T., Franzosa, J., Richard, A., Lougee, R., Gissi, A., Lee, J-Y, Angrish, M., Dorne. J-L., Foster, S., Raffaele, K., Bahadori, T., Gwinn, M., Lambert, J., Whelan, M., Rasenberg, M., Barton-Maclaren, T., Thomas, RS. 2020. Examining the Utility of In Vitro Bioactivity as a Conservative Point of Departure: A Case Study. Toxicol Sci. 173(1):202-225. doi: 10.1093/toxsci/kfz201.
Webster, F., Gagné, M., Patlewicz, P., Pradeep, P., Trefiak, N., Judson, R., Tara S. Barton-Maclaren, TS. 2019. Predicting Estrogenicity of a Group of Substituted Phenols: An Integrated Approach to Testing and Assessment Case Study. Reg Tox Pharm Aug;106:278-291.
Barton-Maclaren TS, Gwinn, MR., Thomas, RS., Rasenberg, M., Kavlock, RJ. 2019. Insights: New Approaches to Chemical Assessment- A progress Report. Bloomberg Environment.
Kienzler A., Connors, K.A., Bonnell, M., Barron M., Beasley A., Inglis C., Norbert-King T., Martin T., Sanderson H., Vallotton N., Wilson P., Embry M. 2019. Mode of Action (MOA) classifications in the EnviroTox Database: Analysis and implementation of a consensus MOA classification. Environ. Toxicol. Chem. 38(10): 2294-2304. DOI: 10.1002/etc.4531
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 3 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.
Publication: 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
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: Comparison of silica and titanium dioxide nano particles showed different responses based on size and surface-modifications. Also, silica nanoparticles were relatively more cytotoxic than titanium oxide nanoparticles, and atmospheric changes appeared to alter these toxicities. Furthermore, internalization of nanoparticles into exposed cells and effects on cellular organelles, namely mitochondrial functioning and cellular energy production were examined. Silica nanoparticle exposures affected key mitochondrial protein levels relevant to oxidative stress and cellular energy production. This work will advance understanding on the health consequences of exposure to NMs and assist in the design of less toxic NMs.
Publications: Liu, Q., Liggio, J., Breznan, D., Thomson, EM., Kumarathasan, P., Vincent, R., Li, K., Li, SM. Oxidative and Toxicological Evolution of Engineered Nanoparticles with Atmospherically Relevant Coatings. Environ Sci Technol. 2019 Mar 19;53(6):3058-3066. doi: 10.1021/acs.est.8b06879
7.2 Living organisms
Government research on living organisms focuses on developing novel and contemporary methods for determining the hazardous characteristics and the pathogenicity potential of various existing and emerging biotechnology microbes in order to support regulatory risk assessments. The research is jointly coordinated between regulators at HC and ECCC.
Research at ECCC on living organisms in 2019-2020 included the following study on methods for assessing microbial-based products.
Viable pathogen identification using DNA sequencing technology in microbial risk assessment
Focus of research: Through the application of genomics tools, methods are developed to ensure that commercial microbial-based products are safe for the environment and for Canadians.
Results: DNA sequencing technology is the preferred screening method to determine if a commercial microbial-based product contains pathogens, however, other definitive microbiological methods may need to be applied to confirm the identity of the microbial species.
Publications: Subasinghe, R.M., Samarajeewa, A.D., Meier, M., Coleman, G., Clouthier, H., Crosthwait, J., Tayabali, A.F., Scroggins, R., Shwed P.S., Beaudette, L.A.. 2018. Bacterial and fungal composition profiling of microbial based cleaning products. Journal of Food and Chemical Toxicology 116:25-31.
Subasinghe, R.M., Samarajeewa A.D., Scroggins, R., Beaudette, L.A.. 2019. Evaluation of denaturing gradient gel electrophoresis (DGGE) and next generation sequencing (NGS) in combination with enrichment culture techniques to identify bacteria in commercial microbial-based products. Journal of Microbiological Methods 161:118-130.
7.3 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.
Ongoing research continued on a wide range of air pollutants, including short lived climate pollutants, ammonia, nitrogen oxides (NOx), sulphur dioxide (SO2), volatile organic compounds (VOCs), ozone, and particulate matter/aerosols. Over 67 research papers were published in peer-reviewed scientific journals in 2019-2020. The following are representative examples of that body of work.
Understanding air pollutant emissions and atmospheric concentrations
Focus of research: Improve understanding of air pollutant emissions and atmospheric concentrations, and the contribution of specific sources such as on-road traffic and the oil sands.
Results: A review of monitoring data from 22 North American sites indicated that atmospheric ammonia concentrations have increased, and that this increase could not be reconciled with reported decreases in emissions. The influence of traffic-related PM2.5 and PAH emissions on air pollution near roads depends more on the proportion of large trucks in the fleet than the total traffic volume.
Publications: Islam, S.M.N., Jackson, P.L., Kharol, S.K., McLinden, C.A., Impact of natural gas production on nitrogen dioxide and sulphur dioxide over Northeast British Columbia, Canada, Atmos. Environ. December 2019, 10.1016/j.atmosenv.2019.117231.
Yao X., Zhang L., Causes of Large Increases in Atmospheric Ammonia in the Last Decade across North America, ACS Omega 2019, 4, 22133-22142, 10.1021/acsomega.9b03284.
Dammers, E., McLinden, C. A., Griffin, D., Shephard, M. W., Van Der Graaf, S., Lutsch, E., Schaap, M., Gainairu-Matz, Y., Fioletov, V., Van Damme, M., Whitburn, S., Clarisse, L., Cady-Pereira, K., Clerbaux, C., Coheur, P. F., and Erisman, J. W.: NH3 emissions from large point sources derived from CrIS and IASI satellite observations, Atmos. Chem. Phys., 19, 12261-12293, https://doi.org/10.5194/acp-19-12261-2019, 2019.
Shephard, M. W., Dammers, E., Cady-Pereira, K. E., Kharol, S. K., Thompson, J., Gainariu-Matz, Y., Zhang, J., McLinden, C. A., Kovachik, A., Moran, M., Bittman, S., Sioris, C. E., Griffin, D., Alvarado, M. J., Lonsdale, C., Savic-Jovcic, V., and Zheng, Q.: Ammonia measurements from space with the Cross-track Infrared Sounder: characteristics and applications, Atmos. Chem. Phys., 20, 2277-2302, https://doi.org/10.5194/acp-20-2277-2020, 2020.
Hilker, N., Wang, J. M., Jeong, C.-H., Healy, R. M., Sofowote, U., Debosz, J., Su, Y., Noble, M., Munoz, A., Doerksen, G., White, L., Audette, C., Herod, D., Brook, J. R., and Evans, G. J.: Traffic-related air pollution near roadways: discerning local impacts from background, Atmos. Meas. Tech., 12, 5247-5261, https://doi.org/10.5194/amt-12-5247-2019, 2019.
Whaley, C. H., Galarneau, E., Makar, P. A., Moran, M. D., and Zhang, J., How much does traffic contribute to benzene and polycyclic aromatic hydrocarbon air pollution? Results from a high-resolution North American air quality model centred on Toronto, Canada, Atmos. Chem. Phys., 20, 2911-2925, 10.5194/acp-20-2911-2020, 2020.
Dabek-Zlotorzynska E., Celo V., Ding L., Herod D., Jeong C.-H., Evans G., Hilker N., Characteristics and sources of PM2.5 and reactive gases near roadways in two metropolitan areas in Canada. Atmos. Environ. Sept 2019, Vol. 218, 10.1016/j.atmosenv.2019.116980
Measurement of carbon dioxide (CO2) emissions
Focus of research: Using aircraft- and satellite-based instruments to measure carbon dioxide (CO2) emissions.
Results: CO2 emission intensities for oil sands facilities are larger than those estimated using publically available data, and overall greenhouse gas emissions may be 30% higher than those reported using existing internationally recommended bottom-up estimation methods. Also, fossil-fuel CO2 emissions and their trends in 8 U.S. megacities during 2006-2017 are inferred by combining satellite-derived NOX emissions with bottom-up city-specific NOX-to-CO2 emission ratios. CO2 emissions calculated from NO2 satellite measurements were found to be in good agreement with existing CO2 emissions data from ground-based measurements.
Publications: Liggio, J., Li, S.-M., Staebler, R.M., Hayden, K., Darlington, A., Mittermeier, R.L., O’Brien, J., McLaren, R., Wolde, M., Worthy, D., Vogel, F., Measured Canadian oil sands CO2 emissions are higher than estimates made using internationally recommended methods., Nature Communications, Volume 10, Issue 1, December 2019, 10.1038/s41467-019-09714-9.
Goldberg, D.L., Lu, Z., Oda, T., Lamsal, L.N., Liu, F., Griffin, D., McLinden, C.A., Krotkov, N.A., Duncan, B.N., Streets, D.G., Exploiting OMI NO2 satellite observations to infer fossil-fuel CO2 emissions from U.S. megacities, Science of the Total Environment, Volume 695, December 2019, 10.1016/j.scitotenv.2019.133805
Alignment of carbon and nitrogen cycles with livestock and crop production in GHG emission inventories from agriculture
Focus of research: ECCC scientists worked with Agriculture and Agri-Food Canada (AAFC) scientists towards the improvement of the representation and alignment of emissions and removals of carbon, and the cycling of nitrogen and emission of nitrous oxide on farms, through livestock and crop production systems.
Results: These studies have improved the relationship between precipitation and nitrous oxide emissions and refined the Canadian nitrous oxide model, quantified the relationship between carbon in perennial soils and beef production and quantified the increase in soil carbon associated with increasing crop productivity and variations in manure application.
Publications: Liang, B.C., A.J. VandenBygaart, J.D. MacDonald, D. Cerkowniak, B.G. McConkey, R.L. Desjardins, D.A. Angers. (2020). Revisiting no-till’s impact on soil organic carbon storage in Canada. Soil Till Res. 198, Article number 104529.
Liang, B.C., J.D. MacDonald, B.G. McConkey, C. Flemming, D. Cerkowniak, A. Blondel, and R.L. Desjardins. (2020). Grazing based cattle production systems impacts on soil organic carbon storage in Canada. Sci Total Env. 718, Article number 137273.
Fan, J., McConkey, B.G., Liang, B.C, Angers, D.A, Janzen, H.H, Kröbel, R, Cerkowniak, D.D, Smith, W.N. (2019) Increasing crop yields and root input make Canadian farmland a large carbon sink. Geoderma 336, 49-58
In 2019-2020, 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 53 articles in peer reviewed scientific journals. These addressed issues such as the effect of air pollutants on birth outcomes and on the development of diseases such as asthma, diabetes, and autism, the risks associated with elevated exposure to traffic and industrial pollutants, and the mechanisms by which air pollutants affect health. Other studies investigated determinants of air pollution exposure in various environments and provided information of use to local air quality management and population health studies.
The following includes a list of some of the projects in which HC was engaged during 2019-2020.
ATOUSSA - Assessing Toxicity of Organics in Urban Source Sectors for Air
Focus of research: This study investigates potential human health risks associated with exposure to chemical mixtures in urban air. The objective is to identify various toxic organics and characterise their relative concentrations at different sites in urban Toronto influenced by different types of emission sources.
Results: The project generated knowledge of the chemical composition of 8 different sites indicative of different sources in the Toronto urban area and how the chemical composition changes from season to season. Several toxicity assays were optimised to determine the most sensitive assays that will enable differentiation of site-specific responses that can be linked to specific chemical components and their respective concentrations in the mixtures. The current study provided a level of comparison with and between various sources in the Toronto region.
Publications: Eftade O. Gaga, Tom Harner, Ewa Dabek-Zlotorzynska, Valbona Celo, Greg Evans, Cheol-Heon Jeong, Sabina Halappanavar, Narumol Jariyasopit, Yushan Su. Polyurethane Foam (PUF) Disk Samplers for Measuring Trace Metals in Ambient Air. Environ. Sci. Technol. Lett.2019,6,9, 545-550. DOI10.1021/acs.estlett.9b00420
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. 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.
Publication: Thomson EM, Kalayci H, Walker M. 2019. Cumulative toll of exposure to stressors in Canadians: an allostatic load profile. Health Reports 30(6):14-21.
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, substantiating the hypothesis that activation of the stress axis is involved in mediating adverse central nervous system impacts of air pollutants. 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: Thomson EM. Air pollution, stress, and allostatic load: linking systemic and central nervous system impacts. Journal of Alzheimer’s Disease, 2019; 69(3):597-614. DOI: 10.3233/JAD-190015
Thomson EM, Filiatreault A, Guénette J. Stress hormones as potential mediators of air pollutant effects on the brain: Rapid induction of glucocorticoid-responsive genes. Environmental Research. 2019 Nov;178:108717. doi: 10.1016/j.envres.2019.108717. Epub 2019 Sep 4.
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 Health Canada 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 3 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 present specific circumstances for the deterioration in air quality and communication tools to specifically address these conditions are needed. Other studies have considered the relationship between short term variability in air quality and diverse health outcomes and different approaches to communicating air pollution health risks.
Publications: Szyszkowicz M. The Air Quality Health Index and all emergency department visits. Environ Sci Pollut Res Int. 2019 Aug;26(24):24357-24361. Epub 2019 Jun 22. DOI: 10.1007/s11356-019-05741-7.
Yao J, Stieb DM, Taylor E, Henderson SB. Assessment of the Air Quality Health Index (AQHI) and 4 alternate AQHI-Plus amendments for wildfire seasons in British Columbia. Canadian Journal of Public Health. 2020 Feb;111(1):96-106.
Szyszkowicz M. Use of two-point models in “Model choice in time-series studies of air pollution and mortality”. Air Quality, Atmosphere & Health. 2020 Feb;13(2):225-32.
Masselot P, Chebana F, Lavigne É, Campagna C, Gosselin P, Ouarda TB. Toward an Improved Air Pollution Warning System in Quebec. International journal of environmental research and public health. 2019 Jan;16(12):2095.
Stieb DM, Huang A, Hocking R, Crouse DL, Osornio-Vargas AR, Villeneuve PJ. Using maps to communicate environmental exposures and health risks: Review and best-practice recommendations. Environmental research. 2019 Sep 1;176:108518.
Effectiveness of the Air Quality Health Index for patients with implanted cardioverter defibrillators
Focus of research: The AQHI is a risk communication tool intended to provide information to the public on current and forecasted air quality conditions. The primary objective is to evaluate the actual effectiveness of the AQHI as an intervention in reducing health risks of patients wearing implantable cardioverter defibrillator (ICD). The secondary objective is to study the associations between daily exposure to outdoor O3, NO2 and PM2.5 as well as AQHI and variations in arrhythmia parameters and other cardiovascular outcomes in this panel of cardiac patients.
Results: The results suggest that air pollution was associated with adverse changes in cardiovascular measures in ICD patients. Advice to avoid exposure to outdoor air pollution based on AQHI may help reduce adverse impacts on cardiovascular measures. Daily mild exercise may benefit cardiovascular function in this cohort of ICD patients.
Publication: Ling Liu, Bruce Urch, Kumaraswamy Nanthakumar, Li Chen, Marc Smith-Doiron, Jeffrey R. Brook, Mary Speck, Frances Silverman, and David M. Stieb. Air pollution, physical activity and cardiovascular function of patients with implanted cardioverter defibrillators: A randomized controlled trial of indoor versus outdoor activity. J. Occup. Environ. Med. December 2019, 62(4):263-271. DOI: 10.1097/JOM.0000000000001795
The association between pregnancy exposure to air pollution and autism in children
Focus of research: The number of children diagnosed with autism spectrum disorder (ASD) has been increasing. Previous studies suggested potential association between pregnancy air pollution exposure and ASD. This project is designed to test 2 hypotheses: (1) prenatal exposure to air pollution is associated with the risk of ASDs in children; and (2) the impact of exposure to air pollution varies according to gestational periods.
Results: The first phase of this project was a systematic review and meta-analysis of previous publications and is intended to summarize the association between maternal exposure to outdoor air pollution and ASD in children by trimester based on recent studies. The review found some evidence for PM2.5, weak evidence for NO2 and little evidence for PM10 and ozone. However, patterns in associations over trimesters were inconsistent among studies and among air pollutants.
Publications: Chun H, Leung C, Wen SW, McDonald J, Shin HH. Maternal exposure to air pollution and risk of autism in children: A systematic review and meta-analysis. Environmental Pollution. 2020 Jan 1;256:113307
Health effects of exposure to ultrafine particles (UFPs)
Focus of research: This study investigates long-term exposure to UFPs on the risk of developing lung, breast and prostate cancers using data from 3 case-control studies. As well, it investigates pregnancy exposure to UFPs on the risk of term low birth weight (< 2500 g), preterm birth and small for gestational age using a provincial birth registry in Ontario for births in the city of Toronto.
Results: Scientific manuscripts (3) have been published based on findings relating UFPs to childhood asthma, congenital heart defects and brain tumours in adults. More specifically, UFP exposures during a critical periods of pregnancy were associated with an increased risk of ventricular septal defect and the onset of asthma in children. Ambient UFPs may also represent a previously unrecognized risk factor for incident brain tumors in adults.
Publications: Lavigne E, Lima I, Hatzopoulou M, Van Ryswyk K, Decou ML, Luo W, van Donkelaar A, Martin RV, Chen H, Stieb DM, Crighton E. Spatial variations in ambient ultrafine particle concentrations and risk of congenital heart defects. Environment international. 2019 Sep 1;130:104953.
Lavigne E, Donelle J, Hatzopoulou M, Van Ryswyk K, Van Donkelaar A, Martin RV, Chen H, Stieb DM, Gasparrini A, Crighton E, Yasseen III AS. Spatiotemporal variations in ambient ultrafine particles and the incidence of childhood asthma. American journal of respiratory and critical care medicine. 2019 Jun 15;199(12):1487-95.
Weichenthal S, Olaniyan T, Christidis T, Lavigne E, Hatzopoulou M, Van Ryswyk K, Tjepkema M, Burnett R. Within-city Spatial Variations in Ambient Ultrafine Particle Concentrations and Incident Brain Tumors in Adults. Epidemiology (Cambridge, Mass.). 2020 Mar;31(2):177.
Spatial modelling to support health studies
Focus of research: HC carries out intensive ambient air pollution monitoring, and develops land-use regression (LUR) models that allow for the prediction of concentrations of pollutants at a neighbourhood or household level. LUR models are being used to support local- and national-scale health studies investigating air pollution impacts on respiratory, cardiovascular (for example, stroke), developmental (for example, birth outcomes, gestational diabetes), autoimmune diseases and cancer outcomes.
Results: Land-Use Regression models and other exposure data developed by Health Canada’s Air Program are now available through several venues including The Canadian Urban Environmental Health Research Consortium (CANUE).
Publication: Goldberg MS, Villeneuve PJ, Crouse D, To T, Weichenthal SA, Wall C, Miller AB. Associations between incident breast cancer and ambient concentrations of nitrogen dioxide from a national land use regression model in the Canadian National Breast Screening Study. Environment international. 2019 Dec 1;133:105182.
Central Experimental Farm Greenspace Effects
Focus of research: Air pollution, traffic related noise and local temperatures are all influenced by features of the urban built environment. In Ottawa, the Central Experimental Farm (CEF) likely plays a prominent role in influencing these exposures, but to date there have been few efforts to evaluate these impacts. The purpose of this study was to characterize air pollution, noise and ambient temperature on and around the CEF, and to determine if the farm has a mitigating impact on these exposures.
Results: Seasonal sampling campaigns (3) were conducted in and around the CEF. The spatial variability of nitrogen dioxide, fine particulate matter, ultra-fine particles, black carbon, volatile organic compounds, ambient temperature, and noise within this area was characterized. The study produced evidence that this large green space can mitigate levels of heat and air pollution in the surrounding area.
Publication: Van Ryswyk K, Prince N, Ahmed M, Brisson E, Miller JD, Villeneuve PJ. Does urban vegetation reduce temperature and air pollution concentrations? Findings from an environmental monitoring study of the Central Experimental Farm in Ottawa, Canada. Atmospheric Environment. 2019 Dec 1;218:116886.
Multi-City Multi-Country (MCC) Collaborative Research Network
Focus of research: Numerous studies have examined the associations between short-term PM exposures and daily mortality. However, most evidence has been obtained from studies in single cities, regions, or countries, and there are challenges in comparing these results and in synthesizing effect estimates because of different modeling approaches and potential publication bias. The Multi-City Multi-Country (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 PM2.5 exposures with daily mortality.
Results: Research papers (2) were published. A paper showed independent associations between short-term exposure to PM10 and PM2.5 and daily all-cause, cardiovascular, and respiratory mortality in more than 600 cities across the globe. The second paper reported on data analyzed from more than 400 locations in 20 countries and provided evidence on the short term association between ozone and mortality
Publications: Liu C, Chen R, Sera F, Vicedo-Cabrera AM, Guo Y, Tong S, Coelho MS, Saldiva PH, Lavigne E, Matus P, Valdes Ortega N. Ambient particulate air pollution and daily mortality in 652 cities. New England Journal of Medicine. 2019 Aug 22;381(8):705-15.
Vicedo-Cabrera AM, Sera F, Liu C, Armstrong B, Milojevic A, Guo Y, Tong S, Lavigne E, Kyselý J, Urban A, Orru H, et al. Short term association between ozone and mortality: global two stage time series study in 406 locations in 20 countries. BMJ. 2020 Feb 10;368.
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 (~ 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: Research papers (5) were published. One paper reported that air pollution exposure increased risk of stroke, a second found an association between exposure to air pollutants and heart failure and acute myocardial infarction (heart attack). Further analysis found that consideration of the chemical components that make up PM2.5 may increase the estimate of the effect of PM2.5 heart attacks and cardiovascular mortality by 10% to 27%. A 4th paper presented links between air pollution and the incidence of diabetes and diabetes related mortality. Finally, another paper reported that long term exposure to traffic noise increases risks of diabetes and hypertension and that this effect was independent of the effects of air pollution.
Publications: Shin S, Burnett RT, Kwong JC, Hystad P, van Donkelaar A, Brook JR, Goldberg MS, Tu K, Copes R, Martin RV, Liu Y. Ambient air pollution and the risk of atrial fibrillation and stroke: a population-based cohort study. Environmental health perspectives. 2019 Aug 26;127(8):087009.
Chen H, Zhang Z, van Donkelaar A, Bai L, Martin RV, Lavigne E, Kwong JC, Burnett RT. Understanding the Joint Impacts of Fine Particulate Matter Concentration and Composition on the Incidence and Mortality of Cardiovascular Disease: A Component-Adjusted Approach. Environmental Science & Technology. 2020 Feb 26;54(7):4388-99.
Bai L, Shin S, Burnett RT, Kwong JC, Hystad P, van Donkelaar A, Goldberg MS, Lavigne E, Copes R, Martin RV, Kopp A. Exposure to ambient air pollution and the incidence of congestive heart failure and acute myocardial infarction: A population-based study of 5.1 million Canadian adults living in Ontario. Environment international. 2019 Nov 1;132:105004.
Shin S, Bai L, Oiamo TH, Burnett RT, Weichenthal S, Jerrett M, Kwong JC, Goldberg MS, Copes R, Kopp A, Chen H. Association between road traffic noise and incidence of diabetes mellitus and hypertension in Toronto, Canada: a population-based cohort study. Journal of the American Heart Association. 2020 Mar 17;9(6):e013021.
Paul LA, Burnett RT, Kwong JC, Hystad P, van Donkelaar A, Bai L, Goldberg MS, Lavigne E, Copes R, Martin RV, Kopp A. The impact of air pollution on the incidence of diabetes and survival among prevalent diabetes cases. Environment international. 2020 Jan 1;134:105333.
Air pollution health effects observed in the Canadian Community Health Survey
Focus of research: The Canadian Community Health Survey (CCHS) is a national cross-sectional survey of the Canadian population that collects information related to health status, health care utilization, and health determinants. The survey has been used to create a cohort with detailed air pollution exposure data and information on a number of important individual-level behavioural risk factors that can be used to investigate the relationships between air pollution and various health outcomes.
Results: The Canada wide coverage of the cohort allowed the investigation of effect of air pollution on population mortality even when pollutant concentrations were low. The results showed that a significant effect and supralinear concentration response at low PM2.5 concentrations. The CCHS data was also applied to an investigation of causal mediators of the relationship between air pollution and dementia. The study found a relationship between long term exposure to air pollutants and increased incidence of dementia and suggested that the effect of air pollution exposure on cardiovascular disease may contribute to the effect on dementia.
Publications: Christidis T, Erickson AC, Pappin AJ, Crouse DL, Pinault LL, Weichenthal SA, Brook JR, van Donkelaar A, Hystad P, Martin RV, Tjepkema M. Low concentrations of fine particle air pollution and mortality in the Canadian Community Health Survey cohort. Environmental Health. 2019 Dec 1;18(1):84.
Ilango SD, Chen H, Hystad P, van Donkelaar A, Kwong JC, Tu K, Martin RV, Benmarhnia T. The role of cardiovascular disease in the relationship between air pollution and incident dementia: a population-based cohort study. International Journal of Epidemiology. 2020 Feb 1;49(1):36-44.
Traffic related air pollution
Focus of research: Traffic-related air pollution (TRAP) is 1 of the major sources of exposure in urban areas and has been associated with a wide range of adverse human health effects. Much of the Canadian population is regularly exposed to TRAP as a result of daily activities (for example, commuting) and a significant portion of the population resides in close proximity to major roadways.
Results: HC conducted a scoping review to develop an evidence map of the epidemiological literature of the human health effects of exposure to TRAP, to support future reviews and assessments.
Publication: Matz CJ, Egyed M, Hocking R, Seenundun S, Charman N, Edmonds N. Human health effects of traffic-related air pollution (TRAP): a scoping review protocol. Systematic reviews. 2019 Dec 1;8(1):223.
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 characterizing air pollution exposure and retrospective birth and child cohorts.
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. Ozone exposure was associated with asthma and eczema in children, while other studies showed complex profiles and source characteristics that were linked to health effects.
Publications: Serrano-Lomelin J, Nielsen CC, Jabbar MS, Wine O, Bellinger C, Villeneuve PJ, Stieb D, Aelicks N, Aziz K, Buka I, Chandra S. Interdisciplinary-driven hypotheses on spatial associations of mixtures of industrial air pollutants with adverse birth outcomes. Environment international. 2019 Oct 1;131:104972.
Buteau S, Shekarrizfard M, Hatzopolou M, Gamache P, Liu L, Smargiassi A. Air pollution from industries and asthma onset in childhood: A population-based birth cohort study using dispersion modeling. Environmental Research. 2020 Jan 25:109180.
To T, Zhu J, Stieb D, Gray N, Fong I, Pinault L, Jerrett M, Robichaud A, Ménard R, van Donkelaar A, Martin RV. Early life exposure to air pollution and incidence of childhood asthma, allergic rhinitis and eczema. European Respiratory Journal. 2020 Feb 1;55(2).
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 2 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.
Publications: Erickson AC, Brauer M, Christidis T, Pinault L, Crouse DL, van Donkelaar A, Weichenthal S, Pappin A, Tjepkema M, Martin RV, Brook JR. Evaluation of a method to indirectly adjust for unmeasured covariates in the association between fine particulate matter and mortality. Environmental research. 2019 Aug 1;175:108-16.
Pappin AJ, Christidis T, Pinault LL, Crouse DL, Brook JR, Erickson A, Hystad P, Li C, Martin RV, Meng J, Weichenthal S. Examining the Shape of the Association between Low Levels of Fine Particulate Matter and Mortality across Three Cycles of the Canadian Census Health and Environment Cohort. Environmental health perspectives. 2019 Oct 22;127(10):107008.
Crouse DL, Erickson AC, Christidis T, Pinault L, van Donkelaar A, Li C, Meng J, Martin RV, Tjepkema M, Hystad P, Burnett R. Evaluating the Sensitivity of PM2. 5-Mortality Associations to the Spatial and Temporal Scale of Exposure Assessment. Epidemiology. 2020 Mar 1;31(2):168-76.
Methods to Pool Non-Linear Concentration-Response Models
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. The study suggested an impact of urban air pollution on human behaviour. This study resulted in the development of a method pooling non-linear risk functions named the Global Exposure Mortality Model (GEMM) for non-accidental deaths. This new approach is used worldwide to determine the impact of fine particulate matter on mortality.
Publications: Szyszkowicz M. Urban air pollution and behavioural disorders. Int Arch Subs Abuse Rehabil 2019 (1):1-7. DOI: 10.23937/iasar-2017/1710005
Szyszkowicz M. Case-Crossover Method with a Short Time-Window. Int J Environ. Res. Public Health 2020, 17(1) 202: DOI: 10.3390/ijerph17010202
7.4 Water quality
Both ECCC and HC continued their water quality research activities.
Trends in flame retardants in Great Lakes fish
Focus of research: To assess temporal changes in concentrations of polybrominated diphenyl ethers (PBDEs) flame retardants in top predator fish in the Great Lakes.
Results: Both Canadian and the US researchers analyzed trends in 5 major PBDE congeners (BDE-47, 99, 100, 153, and 154) in lake trout and walleye in all 5 Great Lakes from 1979 to 2016. Total PBDE concentrations (age-adjusted) increased from 1990 to 2000 (16.3% per year) followed by a rapid decreasing trend from 2000 to 2007 (-19.5% per year). This decrease is associated with the voluntary phasing out of production and use of PBDEs beginning in 2000. Since 2007, the decreasing trend has become smaller (less than -5.5% per year) and relatively unchanged from 2011 to 2015. While BDE-47 continues to decline in most lakes, the concentration of the 4 higher brominated congeners appears to be increasing post 2007. These results indicate increasing fish uptake and bioaccumulation of higher brominated BDE congeners may be related to the transformation of BDE-209 to lower brominated BDE compounds in the Great Lakes environment or food web.
Publication: Zhou, C., Pagano, J., McGoldrick, D.J., Chen, D., Crimmins, B.,S., Hopke, P.K., Milligan, M.S., Murphy, E.W., Holsen, T.M. 2019. Legacy Polybrominated Diphenyl Ethers (PBDEs) Trends in Top Predator Fish of the Laurentian Great Lakes (GL) from 1979 to 2016: Will Concentrations Continue to Decrease? Environ. Sci. Technol. 53: 6650-6659 255. DOI: 10.1021/acs.est.9b00933
Trends in perfluoroalkyl acids (PFAAs) in Great Lakes precipitation and surface waters
Focus of research: To assess temporal changes in concentrations of perfluoroalkyl acids in wet precipitation and surface water between 2006 and 2018 in the Canadian Great Lakes in relation to regulatory changes.
Results: Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) concentrations generally decreased in precipitation, likely in response to phase-outs/regulatory actions. In comparison, concentrations of shorter-chained PFAA, which are not regulated in Canada did not decrease and those of perfluorohexanoate and perfluorobutanoate (PFBA) recently increased, which could be due to their use as replacements, as the longer-chained PFAAs are being phased-out by industry. Our results suggest that source control of shorter-chained PFAAs may be slow to be reflected in environmental concentrations due to emissions far from the location of detection and continued volatilization from existing in-use products and waste streams.
Publication: Gewurtz, S.B., Bradley, L.E., Backus, S., Dove, A., McGoldrick, D.J., Hung, H., Dryfhout-Clark, H. 2019. Perfluoroalkyl Acids in Great Lakes Precipitation and Surface Water (2006-2018) Indicate Response to Phase-outs, Regulatory Action, and Variability in Fate and Transport Processes. In Environ. Sci. Technol. 53: 8543-8552. https://pubs.acs.org/doi/10.1021/acs.est.9b01337
Spatial and temporal trends of bisphenol A in Canadian surface waters
Focus of research: Studies have shown that BPA, an industrial chemical used in plastics production, is entering the environment through wastewaters, washing residues, physical-chemical breakdown of end products during disposal and recycling, and has been found in some leachate from landfills. Freshwater samples were collected and analysed for Bisphenol A (BPA), at 44 sampling sites in Canada from 2012 to 2018.
Results: The resultant concentrations of PBA in the samples ranged from 3.05 to 1888.51 ng/L, with concentrations of BPA in 64% of the samples under the detection limit of the laboratory. In comparison, the Federal Environmental Quality Guideline for the protection of aquatic life is 3500 ng/L. Detections of BPA in water samples were more frequent in urban and municipal wastewater treatment plants-associated sites. Additionally, there does not seem to be a statistically significant temporal (upward or downward) or spatial trend in BPA concentrations in Canadian surface waters from 2012 to 2018. Overall, Canadian BPA results are of similar concentrations to that of other countries in Asia and Europe.
Publication: Lalonde B., Garron C. 2020. Spatial and Temporal Distribution of BPA in the Canadian Freshwater Environment. Arch of Env. Contam and Toxicol. 78: 568-578 https://link.springer.com/article/10.1007/s00244-020-00721-2
Fate, transport and bioaccumulation of emerging and legacy perfluoroalkyl substances
Focus of research: The focus of this research is to contribute environmental fate data on emerging and legacy perfluoroalkyl substances (PFAS), from various sources including Lake Ontario sediment and wastewater influent and effluent.
Results: In a Lake Ontario sediment core that was sectioned, dated, and analyzed for perfluoroalkyl substances (PFAS), a deposition profile was constructed for individual PFAS congeners from 1950 to 2017. Perfluoroalkane sulfonic acids (PFSA) and perfluoroalkyl carboxylic acids (PFCA) were detected in all samples 1950 to 2017. PFOS increased exponentially from the 1950s until 2008, followed by a decline. The 2nd and 3rd highest concentrations were attributed to perfluorooctanoate (PFOA) and (PFUnDA). PFOA increased until 1996 followed by decline and a plateau from 2000 to the present. Perfluoroundecanoate (PFUnDA) and other long chain PFCA do not display a decline and have increased in deposition since 2000.
PFAS were analyzed in raw wastewater influent sampled from 14 different wastewater treatment plants in Canada with a variety of treatment approaches: primary treatment with chemical addition, facultative lagoon, advanced secondary treatment, and advanced biological nutrient removal. Total PFAS (20 congeners) in influent ranged from 11 ng L-1 to 444 ng L-1 (91 ± 100 ng L-1) with a median value of 42 ng L-1. In effluent, total PFAS ranged from 20 ng L-1 to 239 ng L-1 (66 ± 59 ng L-1) with a median value of 42 ng L-1. However, on an individual PFAS congener basis, greater concentrations of certain PFAS in effluent suggests their production via transformation of organofluorine precursors in the WWTP process.
Publication: Pickard, H.M., Criscitiello, A.S., Persaud, D., Spencer, C., Muir, D.C.G., Lehnherr, I., Sharp, M.J., De Silva, A.O., Young, C.J. 2020. Ice Core Record of Persistent Short-Chain Fluorinated Alkyl Acids: Evidence of the Impact from Global Environmental Regulations, Geophys. Res. Lett., 47, e2020GL087535.
Aquatic toxicology of silver nanoparticles
Focus of research: Silver nanoparticles (nAg) represent 1 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 fish were examined.
Results: The surface coatings influenced bioavailabilty and toxicity of silver nanoparticles. Silver nanoparticles coated with polyvinylpyrolidone were the most bioavailable in fish compared to citrate, silicate and bis-polyethyleneimine coatings. The toxicity of the form of silver nanoparticles of similar size and coating was greater with cubic nanomaterials compared to spherical and prismatic nano-silver. In this approach, polystyrene nanoparticles were used as inert surrogates where crowding effects could be measured in tissues without the reactivity of silver.
Publications: Auclair J, Turcotte P, Gagnon C, Peyrot C, Wilkinson KJ, Gagné F. 2019. The influence of surface coatings on the toxicity of silver nanoparticle in rainbow trout. Comp Biochem Physiol C Toxicol Pharmacol. 226: 108623.
Auclair J, Turcotte P, Gagnon C, Peyrot C, Wilkinson KJ and F, Gagné 2019. The Influence of Surface Coatings of Silver Nanoparticles on the Bioavailability and Toxicity to Elliptio complanata Mussels. Journal of Nanomaterials e ID 7843025.
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 NPs were detected in the digestive gland and produced biophysical effects in the digestive gland of freshwater mussel such as anisotropy, viscosity, and changes in glucose metabolism enzyme dissipative activities and time-dependent viscosity. An additional studied concluded that NPs are bioavailable to hydra and lead to lipid peroxidation (LPO) and lipid mobilization in hydra.
Publications: Auclair J, Quinn B, Peyrot C, Wilkinson KJ, Gagné F. 2020. Detection, biophysical effects, and toxicity of polystyrene nanoparticles to the cnidarian Hydra attenuata. Environ Sci Pollut Res Int. 27: 11772-11781.
Auclair J, Peyrot C, Wilkinson KJ, F., Gagné, 2020. Biophysical effects of polystyrene nanoparticles on Elliptio complanata mussels. Environ Sci Poll Res. https://doi.org/10.1007/s11356-020-08920-
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 (NP Bi2O3, CeO2, CuO, MnO2, NiO, Ag, ZnO, ZrO2) 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: Silver nanoparticles and transformation products were evaluated in Canadian municipal wastewater effluents as potential additional silver sources in natural waters. The bioavailability and toxicity of CeO2 and Ag NPs and transformed products to different aquatic organisms were documented and environmental exposure was characterized as influenced by the nature and size of particles. The transformation of CuO and ZnO NPs was significant and key information for environmental exposure assessment (persistence and bioaccumulation).
Publications: Auclair, J., Turcotte, P., Gagnon C., Gagné F. 2020. Toxicity of copper oxide nanoparticles to rainbow trout juveniles. Current Topics Toxicol. 16: 1-11.
Auclair J, André C, Peyrot C, Wilkinson KJ, Turcotte P, Gagnon C, Gagné F. 2019. Combined effects of surface waters and CeO nanoparticle in zebra mussels. Invert. Surv. J. 16: 153-163.
Auclair J, Turcotte P, Gagnon C, Peyrot C, Wilkinson KJ, Gagné F. 2019. The influence of surface coatings of silver nanoparticles on the bioavailability and toxicity of freshwater mussels. J. Nanomaterials, ID 7843025, 10 p. doi.org/10.1155/2019/7843025.
Gagné F, Auclair J, Turcotte P, Gagnon C, Peyrot C, Wilkinson KJ. 2019. The influence of surface waters on the bioavailability and toxicity of zinc oxide nanoparticles in freshwater mussels. Comp Biochem Physiol - Part C. 219:1-11.
Toxicity of tire particle leachates to embryonic fish
Focus of research: ECCC scientists assessed the aquatic toxicity of leachates from particles of tires. Tire particles are a class of microplastics that enter the environment. Tires lose up to 1 kg per year of rubber (per car, with normal driving), and these small bits of rubber are washed from road surfaces into drains, often ending up in rivers.
Results: The effects of leachates from tire particles were assessed by exposing embryonic fish. Leachates from tire particles were toxic to fish. Toxicity was greater if the tire particles were leached at higher temperatures (34 °C compared to 25 °C) and if tire particles were leached with vigorous stirring (simulating high rainstorm turbulence). The leachates decreased fish embryo hatch success, and any surviving hatched fish were smaller. The study is continuing in order to assess which chemicals in the tire particles were harming the fish.
Publications: Kolomijeca A, Parrott J, Khan H, Shires K, Clarence S, Sullivan C, Chibwe L, Sinton D, Rochman CM. 2020. Increased temperature and turbulence alter the effects of leachates from tire particles on fathead minnow (Pimephales promelas). Environmental Science & Technology. 54(3):1750-1759.
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