Risk management scope for zinc and soluble zinc compounds under the zinc and its compounds grouping
Official title: Risk management scope for zinc and soluble zinc compounds under the zinc and its compounds grouping
Environment and Climate Change Canada
Summary of proposed risk management
This document outlines the risk management options under consideration for zinc and soluble zinc compounds, which have been proposed to be harmful to the environment.
In particular, the Government of Canada is considering reducing anthropogenic releases of zinc to water from the following sectors or activities:
- Metal mining: by applying the updated zinc effluent limits (amended in 2018) in the Metal and Diamond Mining Effluent Regulations (MDMER), and reviewing information received from regulated mines in response to environmental effects monitoring requirements under these regulations to determine if additional regulatory or non-regulatory risk management is appropriate.
- Base metals smelting and refining: by addressing facilities that are subject to the MDMER through the action proposed above for metal mining. Base metals smelting and refining facilities that are not subject to the MDMER are not proposed for risk management action.
Interested stakeholders are invited to provide the following information to help in refining ECCC’s risk analysis:
- Dissolved or total concentrations of zinc in effluents, receiving environments, and reference areas for surface waters.
- Measurements of dissolved organic carbon (DOC), pH, and hardness related to these dissolved concentrations of zinc.
This information should be provided on or before August 28, 2019, to the contact identified in Section 8 of this document.
Under phase 3 of the Chemicals Management Plan (CMP3), ECCC and HC are conducting assessments of a variety of metals that may also identify metal mines and base metals smelting and refining facilities as sources of risk. ECCC is considering the risk management actions for zinc and soluble zinc compounds as part of a more comprehensive strategy to manage the metals assessed as toxic under CMP3. Implementation of this strategy would begin in 2023, when all risk assessments and risk management approaches for these metals will have been completed and published. This strategy will be focused on effluents rather than on single metals and will reduce the administrative burden on implicated sectors that would otherwise result from implementing multiple risk management approaches (e.g. repeated amendments to the MDMER) over a five year period, for metals assessed and found to be toxic.
Note: The above summary is an abridged list of options under consideration to manage these substances and to seek information on identified gaps. Refer to section 3 of this document for more details in this regard. It should be noted that the proposed risk management options may evolve through consideration of additional information obtained from the public comment period, literature, and other sources.
The Canadian Environmental Protection Act, 1999 (CEPA) (Government of Canada, 1999) provides the authority for the Minister of the Environment and the Minister of Health (the Ministers) to conduct assessments to determine if substances are toxic to the environment and/or harmful to human health as set out in section 64 of CEPAFootnote 1 Footnote 2, and if so to manage the associated risks.
As part of the third phase of the Chemicals Management Plan, the Ministers plan to assess and manage, where appropriate, the potential health and ecological risks associated with approximately 1550 substances (Government of Canada, 2016).
The Minister of the Environment and the Minister of Health have conducted a screening assessment of zinc and its compounds . The 75 substances, listed in Annex A are included in the zinc and its compounds grouping of the Chemicals Management Plan (Government of Canada, 2017) and the Revised In Commerce List (Government of Canada, 2010) (Health Canada, 2017). Sixty-four substances in this group were identified as priorities for assessment as they met categorization criteria under subsection 73(1) of CEPA. Eleven additional substances were identified for further consideration following prioritization of the Revised In Commerce List (R-ICL). The draft screening assessment focuses on the zinc moiety and therefore considers zinc in its elemental form, zinc-containing substances, and zinc released in dissolved, solid or particulate form. As such, it is not limited to consideration of the 76 substances listed in Annex A.
Environment and Climate Change Canada (ECCC) and Health Canada conducted a joint scientific assessment to evaluate zinc and its compounds in Canada. A notice summarizing the scientific considerations of the draft Screening Assessment Report for these substances was published in the Canada Gazette, Part I, on June 29, 2019 (ECCC and Health Canada, 2019). For further information on the draft Screening Assessment Report for Zinc and its Compounds, refer to the draft screening assessment.
2.1 Draft screening assessment report conclusion
On the basis of the information available, the draft Screening Assessment Report proposes that zinc and soluble zinc compounds are toxic under section 64(a) of CEPA because they are or may be entering the environment in a quantity or concentration or under conditions that have or may have an immediate or long-term harmful effect on the environment or its biological diversity (ECCC and Health Canada, 2019).
The draft Screening Assessment Report also proposes that zinc and soluble zinc compounds meet the criteria for persistence, but do not meet the criteria for bioaccumulation, as defined in the Persistence and Bioaccumulation Regulations made under CEPA (Government of Canada, 2000).
The risks of concern, identified in the draft Screening Assessment Report, are based on the release of zinc from metal mining and some base metals smelting and refining. As such, this document will focus on these activities and exposure sources of concern (refer to section 5.2).
2.2 Proposed recommendation under CEPA
On the basis of the findings of the draft screening assessment conducted as per CEPA, the Ministers propose to recommend that zinc and soluble zinc compounds be added to the List of Toxic Substances in Schedule 1 of the Act Footnote 3.
The Ministers will take into consideration comments made by stakeholders during the 60-day public comment period on the draft Screening Assessment Report and Risk Management Scope document. If the Ministers finalize the recommendation to add zinc and soluble zinc compounds to Schedule 1, a risk management instrument must be proposed and finalized within a set period of time, as outlined in sections 91 and 92 of CEPA (refer to section 8 for publication timelines applicable to this group of substances).
3. Proposed risk management
3.1 Proposed environmental objective
Proposed environmental objectives are quantitative or qualitative statements of what should be achieved to address environmental concerns.
For this substance grouping, the proposed objective is focused on addressing the exposure sources of concern from the sectors outlined in section 5 of this document. As such, the proposed environmental objective for zinc and soluble zinc compounds is to reduce anthropogenic releases of zinc and soluble zinc compounds to water so as not to exceed levels observed to cause adverse effects to aquatic organisms.
3.2 Proposed risk management objective
Proposed risk management objectives set quantitative or qualitative targets to be achieved by the implementation of risk management regulations, instrument(s) and/or tool(s) for a given substance or substances.
In this case, the proposed risk management objective for zinc and soluble zinc compounds is to achieve the lowest level of releases of zinc and soluble zinc compounds to water that is technically and economically feasible, taking into consideration socio-economic factors and natural background concentrations.
Such objectives will be refined on the basis of consultation with stakeholders, the proposed risk management options, consideration of further information received, the outcome of the final Screening Assessment Report, and socio-economic and technical considerations (such as may be outlined in section 6 of this document).
Revised environmental and/or human health and risk management objectives should next be presented in the Risk Management Approach document that will be published concurrently with the final Screening Assessment Report for these substances, or in subsequent risk management documents (e.g. consultation document on proposed instrument), as the case may be.
3.3 Proposed risk management options under consideration
To achieve the proposed risk management objective and to work towards achieving the proposed environmental objective, the risk management options under consideration for zinc and soluble zinc compounds will focus on reducing releases of zinc and soluble zinc compounds to water from the sectors of concern identified in the draft Screening Assessment – metal mining and base metals smelting and refining facilities that combine their effluent with metal mines. These proposed actions are described below.
Note that the proposed risk management options, described in this document, are preliminary and subject to change. Following the publication of this document and publication of other metal assessments, additional information obtained from the public comment period and from other sources will be considered, along with the information presented in this document, in further instrument selection and development processes Footnote 4, if required. The risk management options outlined in this document may also evolve through consideration of assessments and risk management options published for other CMP substances to ensure effective, coordinated, and consistent risk management decision-making.
3.3.1 Metal mining
The existing risk management instrument for zinc in effluents discharged from the metal mining sector is the Metal and Diamond Mining Effluent Regulations (MDMER) under the Fisheries Act (Government of Canada, 2018).
The MDMER prescribe effluent concentration limits for a list of harmful substances including for zinc at 0.50 mg/L for existing mines after June 1, 2018, and a lower limit of 0.40 mg/L for any new mines after June 1, 2021.
Under phase 3 of the Chemicals Management Plan (CMP3), ECCC and HC are conducting assessments of a variety of metals that may also identify metal mines as sources of risk. Following publication of these metal assessments, ECCC will review the information received from regulated mines in response to environmental effects monitoring requirements under MDMER to determine if additional regulatory or non-regulatory risk management of effluents from metal mines is appropriate for one or more assessed metals.
ECCC is considering the RM actions for zinc and soluble zinc compounds as part of a more comprehensive strategy to manage the metals assessed as toxic under CMP3. Implementation would begin in 2023, when all risk assessments and risk management approaches for these metals will have been completed and published. Risk management is focused on effluents, rather than on single metals. The strategy will reduce the administrative burden on metal mines that would otherwise result from implementing multiple risk management approaches (e.g. repeated amendments to the MDMER) over a five year period, for metals assessed and found to be toxic.
3.3.2 Base metals smelting and refining
Base metal and smelting facilities vary significantly in terms of their processes and products, and are therefore expected to have varying levels of zinc in their effluent, ranging from insignificant to high enough to be a source of concern. The MDMER apply to 6 out of 12 existing smelters and refineries that combine their effluent with that of a metal mine effluent. ECCC would apply the same RM approach as described for metal mining.
For the remaining 6 facilities that do not combine their effluents with metal mines, no risk management is proposed.
3.4 Risk management information gaps
For the purpose of risk characterization, measured zinc concentration (dissolved and total) and toxicity modifying factors (TMF), hardness, pH and dissolved organic carbon (DOC) values reported under Environmental Effects Monitoring (EEM) and MDMER were used to calculate the Predicted No Effect Concentration where available. In exceptional cases where these values were unavailable, central tendencies of TMFs were developed for the ecozones and certain Great Lakes. Ecozone geometric means for total hardness and DOC, and average pH were used in substitution.
Interested stakeholders are invited to provide further information, as outlined below, to help in refining ECCC’s risk analysis:
- Dissolved concentrations of zinc in effluents, receiving environments, and reference areas for surface waters.
- Measurements of dissolved organic carbon (DOC), pH, and hardness related to these dissolved concentrations of zinc.
Should stakeholders have further information to help address these gaps, they should provide it ideally on or before August 28, 2019 to the contact identified in section 8 of this document.
4.1 General information on zinc and its compounds
Zinc occurs naturally in the terrestrial crust as five stable elemental (metallic) forms. Zinc compounds considered in the draft Screening Assessment belong to various categories or subgroups including elemental zinc, inorganic compounds, organic-metal salts, organometallic compounds, and compounds of “unknown or variable composition, complex reaction products, or biological materials”.
Most of the zinc compounds on the Domestic Substances List may dissociate or degrade to release zinc. Metallic zinc is insoluble, whereas the solubilities of different zinc compounds range from insoluble (for oxides, carbonates, phosphates, and silicates) to soluble (for sulphates and chlorides) (CCME, 1999)
Sphalerite containing zinc sulphide is the most important zinc ore - over 95% of the world’s zinc is produced from this mineral (IZA, 2018). Zinc concentrate is produced from zinc ore, but it is also a by-product/co-product in the mining and production of other metals, including precious metals and lead (NRCan, 2018a).
4.2 Current uses and identified sectors
Zinc and its compounds have a wide array of industrial and domestic applications.
The main use of refined zinc (i.e., 50% of the global production) is for galvanizing iron and steel products (e.g., pipes, wires, etc.) to prevent corrosion and rust (NRCan, 2018a). The remaining global consumption of zinc is approximately 25% in the transportation sector and 23% for consumer goods (IZA, 2018), including electronics, electrical appliances, sunscreen, dry cell batteries, and tires. It is also used with copper to make brass. Zinc oxide (ZnO, CAS RN1314-13-2) is the compound most commonly used in industrial applications (ECCC, 2009 ) (ECCC, 2013).
Uses of zinc compounds and the sectors where use occurs in Canada were also identified from the Domestic Substances List Inventory Update Phase 1 and Phase 2 surveys for 2008 and 2011, respectively ( (ECCC, 2009 ); (ECCC, 2013) and from the National Pollutant Release Inventory (NPRI), which provides public information on zinc release in the environment (ECCC, 2016). The results indicate that major uses of zinc in Canada involve activities of the following sectors: iron and steel mills and ferro-alloy manufacturing; medical, health products and veterinary; hardware manufacturing; pulp, paper and paperboard mills; animal food manufacturing and crop production; metal products manufacturing and foundries; and chemical manufacturing.
In Canada, other sources of anthropogenic releases of zinc to the environment include electroplating, road surface runoff, corrosion of zinc alloys and galvanized surfaces, and erosion of agricultural soil (Weatherly, Lakes, & Rogers, 1980) (Mirenda, 1986). Zinc is also dispersed from corroded galvanized electrical transmission towers for at least 10 km by runoff and by wind-driven spray and water droplets from the towers (Jones & Burgess, 1984).
4.2.1 Metal mining
Canada is one of the larger producers of zinc concentrate globally, but China represents almost half the world production (NRCan, 2018a). In terms of zinc ore reserves, Canada represents about 3% of the world with Australia having the greatest abundance at 29% and China in second at 18% (NRCan, 2018a).
Canadian mines produced 272 000 tonnes of zinc concentrate in 2015 and increased production to 322 000 tonnes in 2016 (NRCan, 2018a). However, production has generally decreased since 2008 and the increase in 2016 represents only about half the quantity produced in 2008 (NRCan, 2018a). In 2015, zinc was produced from mines located in British Columbia, Manitoba, Ontario, Quebec, Yukon, New Brunswick and Newfoundland and Labrador (ECCC, 2017)
Zinc ore may be extracted from underground or above ground mines in Canada. The processing of ore during extraction and concentration generates dust that may escape and be deposited nearby, and produces effluent which may be stored in tailings ponds or treated and released to surface water. The generated dusts, potential leachates from tailings ponds, and effluent releases to surface water are all pathways from which zinc may be released into the surrounding environment.
Mines and mills, even if they do not produce zinc, may release zinc to the environment, given that this metal is present in a variety of ores.
4.2.2 Base metals smelting and refining
In 2016, Canada was the third largest producer of refined zinc (from both mined and recycled sources) with a production of 686 000 tonnes from refineries located in British Columbia, Manitoba, and Quebec (NRCan, 2018a).
Canadian smelters imported 414 000 tonnes of zinc in concentrates in 2016, compared to 532 000 tonnes in 2015 (NRCan, 2018a). In 2016, 94% of zinc metal was exported to the United States (NRCan, 2018a).
Base metals smelting and refining facilities produce one or more metals, such as copper, lead, nickel, and cobalt, from feed material that primarily comes from ores. They also produce intermediate and compound products and other saleable metals, such as precious metals.
The smelting process uses heat and chemical reduction to extract the metal from mined ores. Traces of zinc are found in many mined ores, but primarily ores with copper or lead deposits. Zinc may be intermediate products, residues or main products from the smelting or refining process.
4.2.3 Iron and steel manufacturing
In 2016, Canada was the eighth largest producer of iron ore in the world representing 2% of the global production. The primary use of iron ore, at 98%, is to make steel. Canada’s estimated crude steel production for 2016 was 12.6 million tonnes (NRCan, 2018b).
Zinc is used in the iron and steel manufacturing process, at the end, as a coating that is applied to iron and steel products to prevent corrosion and rust. This process is called galvanizing and represents almost 50% of the global use of zinc.
There are currently 8 facilities equipped with a galvanizing processing step, four of which are located in Ontario, two in Quebec, one in Manitoba and one in Saskatchewan. In 2015, the Canadian steel industry exported 6 million tonnes, but imported 8 million tonnes, of semi-finished and finished steel products (NRCan, 2018b).
4.2.4 Publicly owned wastewater treatment systems
Effluent from wastewater treatment systems (WWTS) may contain zinc despite wastewater treatment. The source of zinc in WWTS effluent originates from consumer, commercial, or industrial uses upstream of the plant.
4.2.5 Other uses and sectors
Zinc and soluble zinc compounds are used or found incidentally, due to their natural occurrence, in a variety of other sectors; however, the draft Screening Assessment Report did not identify risks from these uses or releases associated with these activities.
The sectors or exposure scenarios, which were evaluated, but not described in detail in the draft Screening Assessment Report, include oil sands, pulp and paper, alternatives to lead wheel weights, and rubber wear from tires.
5. Exposure Sources and Identified Risk
5.1 Natural Sources
Natural sources of zinc in the environment include the weathering of zinc-enriched rocks, soils and sediments by wind and water (Clement Associates, 1989). Erosion of soils naturally enriched with zinc particularly accounts for a large input of zinc into water (CCME, 2006). Additional sources include forest fires, volcanic activity, and aerosol formation above seas (Singh, 2005). Globally, the largest source of natural emissions of zinc to the atmosphere is sea salt spray (Richardson, Garrett, Mitchell, Mah-Paulson, & Hackbarth, 2001).Mean predicted natural emission rates from the various natural sources are 4.6x106 kg/year for Canada, 3.8x107 kg/year for North America, and 5.9x109 kg/year globally (Richardson, Garrett, Mitchell, Mah-Paulson, & Hackbarth, 2001).
Naturally occurring background levels of zinc were identified in the draft Screening Assessment Report and were taken into consideration when estimating the exposure of ecological receptors to zinc-containing substances.
5.2 Anthropogenic releases to the environment
Anthropogenic releases of zinc to the environment have been identified in the draft Screening Assessment Report as posing a risk in some sectors, which are identified below, particularly when released directly to the aquatic environment.
5.2.1 Metal mining
In 2016, 79 mining facilities in Canada reported releases, disposal and/or off-site recycling of zinc and its compounds to the National Pollutant Release Inventory (ECCC, 2016). These facilities reported on-site releases of 32 tonnes to air, 49 tonnes to water and 6 tonnes to land, while on-site disposal amounted to 48 559 tonnes and off-site disposal was 42 tonnes (ECCC, 2016). It should be noted that “disposal” includes information on the disposal of tailings and waste rock, which tend to be disposed of on-site.
Data presented in the draft Screening Assessment Report, pulled from provincial environmental monitoring databases and data submitted under the Environmental Effects Monitoring requirements, indicate that zinc releases from this sector are likely the cause of the elevated zinc levels found near these sites.
For this sector, dissolved zinc concentrations in water bodies and total zinc concentrations in sediment and soils near sources of releases may exceed estimated no-effect levels for aquatic organisms, and sediment-dwelling organisms.
5.2.2 Base metals smelting and refining
In 2016, 12 smelters and refineries reported zinc and its compounds to the National Pollutant Release Inventory (ECCC, 2016). These facilities reported on-site releases of 94 tonnes to air, 241 kg to water and 0 to land, while on-site disposal amounted to 355 kg, off-site disposal was 53 tonnes and off-site recycling was 6051 tonnes (ECCC, 2016).
While the focus of risk management will be the release of zinc and soluble zinc compounds to water, the draft Screening Assessment Report also identifies the release of zinc to air from the base metals smelting and refining sector as a potentially significant contributor to zinc levels in environmental media.
Releases varied significantly among facilities, as expected, due to their different processes and products. Modelled data of releases to water and measured data in water, sediment and soil indicate that releases from this industrial activity may contribute to the elevated levels of zinc found near the facilities that combine their effluent with metal mines.
5.2.3 Iron and steel
In 2016, 26 iron and steel facilities reported zinc and its compounds to the NPRI. This includes all iron and steel facilities and not just those that have galvanizing. These facilities reported on-site releases of 77 tonnes to air, 9.7 tonnes to water and 5 kg to land, while on-site disposal amounted to 5 389 tonnes, off-site disposal was 9 135 tonnes and off-site recycling was 14 523 tonnes (ECCC, 2016).
This sector was identified as a source of zinc, but not as a risk.
5.2.4 Publicly owned wastewater treatment systems (WWTS)
In 2016, 20 wastewater treatment facilities in Canada reported releases, disposal and/or off-site recycling of zinc and its compounds to the NPRI. A total of 125 tonnes were released to water (from 15 facilities) and 1.2 tonnes to air. Off-site disposal, which includes off-site treatment prior to disposal, was 231 tonnes, and a total of 35 tonnes were recycled off-site.
However, based on a risk characterization conducted for 21 WWTS facilities across Canada, this sector was identified as a source of zinc, but not as a risk.
6. Risk management considerations
6.1 Alternatives and alternate technologies
For sectors of concern identified in the draft Screening Assessment Report, it is not expected that chemical alternatives or alternate process technologies would be a practical approach to minimizing releases of zinc.
Additional effluent control technologies (e.g., additional on-site or off-site effluent treatment), process optimization, and recovery of waste metals at the end of the process may be effective approaches for most sectors, as appropriate and economically feasible.
6.2 Socio-economic and technical considerations
Socio-economic factors will be considered in the selection process for a regulation or instrument respecting preventive or control actions, and in the development of the risk management objective(s). Socio-economic factors will also be considered in the development of regulations, instrument(s) or tool(s) as identified in the Cabinet Directive on Regulatory Management (TBS, 2012) and the guidance provided in the Treasury Board document Assessing, Selecting, and Implementing Instruments for Government Action (TBS, 2007).
7. Overview of existing risk management
7.1 Related Canadian risk management context
7.1.1 Metals mines
The existing risk management instrument for zinc in effluent discharged from the metal mining sector is the Metal and Diamond Mining Effluent Regulations (MDMER) under the Fisheries Act (Government of Canada, 2018)
The MDMER prescribe maximum concentration limits in effluent for certain harmful substances including for total zinc at 0.50 mg/L (monthly mean) for existing mines and a lower limit of 0.40 mg/L (monthly mean) for any new mines after June 1, 2021. MDMER also require environmental effects monitoring (EEM) to identify potential effects caused by effluents on fish, fish habitat and use by humans of fish. EEM is a science-based performance measurement tool used to evaluate the adequacy of effluent regulation. EEM studies include: water quality monitoring; effluent chemical characterization; effluent sublethal toxicity testing; and, biological monitoring in the receiving environment.
For complete details on the MDMER refer to: (Government of Canada, 2018) http://laws-lois.justice.gc.ca/eng/regulations/SOR-2002-222/index.html
In 2009, Environment Canada published the Environmental Code of Practice for Metal Mines, according to subsection 54(4) of CEPA, to support the previous Metal Mining Effluent Regulations (MMER) and to include other subjects that are not dealt with in the MMER, which may have an influence on the environmental impact of mining operations. The objective of the Code is to identify and promote recommended best practices to facilitate and encourage continual improvement in the environmental performance of mining facilities throughout the mine life cycle (ECCC, 2009).
7.1.2 Base metal smelting and refining
Atmospheric emissions from smelters and refineries were assessed under the Priority Substances List and concluded to be toxic under CEPA (EC, HC, 2001).
Base metals smelting and refining facilities were subject to a Pollution Prevention Planning Notice published in 2006. The Notice includes release targets for particulate matter, which contains most of the metals emitted to air, including zinc. The Notice requires facilities to take into consideration a number of factors including the Environmental Code of Practice for Base Metals Smelters and Refineries, which recommends particulate matter emission limits to air and effluent limits for chemical parameters and certain metals including zinc. The Code of Practice lists an effluent limit for zinc at a maximum monthly mean concentration of 0.50 mg /L. In addition, the Code of Practice recommends that each facility design and operate effluent discharge systems, taking local conditions into account to obtain a maximum ambient water quality objective of 30 µg/L for total zinc (ECCC, 2006).
The base metals smelting and refining facilities subject to the notice reduced particulate matter releases by a total of 50% between 2005 and 2015.
As a result of the implementation of the Base-Level Industrial Emission Requirements (BLIERs), it is expected that particulate matter emissions will be further reduced from that of 2015 levels. Since most metals from these facilities are discharged to the atmosphere as particulate matter emissions, it is anticipated that emissions of metals, including zinc, would also be reduced as a co-benefit of particulate matter emission reductions. While zinc is not specifically monitored in the emissions or in the environment as part of the BLIERs program, it is expected that zinc reductions will be reflected in the annual emissions data reported by smelters and refineries to the National Pollutant Release Inventory (NPRI).
7.1.3 Iron and steel
Ontario Regulation 214/95: Effluent Monitoring and Effluent Limits - Iron and Steel Manufacturing Sector monitors and controls the quality of effluent discharged from iron and steel plants in Ontario (Government of Ontario, 1995). Industrial facilities that discharge wastewater directly into Ontario’s lakes and rivers report zinc loadings for process effluent, once-through-cooling-water effluent and combined effluent (Government of Ontario, 2016) to the ministry via the Ministry of the Environment Wastewater System (MEWS) web application.
7.1.4 Publicly-owned wastewater treatment systems (WWTS)
The Wastewater Systems Effluent Regulations, established under the Fisheries Act, include mandatory minimum effluent quality standards that can be achieved through secondary wastewater treatment (Government of Canada, 2012). Although the Regulations do not directly target zinc, the requirement for at least secondary treatment, where there is currently no or primary treatment, is expected to generate co-benefits for industrial sectors that send their effluent to a publicly owned WWTS, as secondary treatment has been shown to reduce the quantities of zinc released (ECCC and Health Canada, 2019)
7.1.5 National water quality guidelines
Canadian Council of Ministers of the Environment (CCME) published a revised Zinc Canadian Water Quality Guideline for the Protection of Aquatic Life (CWQGPAL) for fresh water in September 2018. ECCC contributed to the revised zinc CWQGPAL for CCME and it is based on dissolved concentrations. It includes equations for both short-term and long-term exposure that account for relevant toxicity modifying factors, including water hardness, pH and dissolved organic carbon. The dSAR for zinc uses the CWQGPAL in calculation of PNEC values.
The largest cities in Canada all have limits in place for zinc. Toronto’s by-law limits the concentration of total zinc that can be discharged to the wastewater collection system to 2000 µg/L, and the concentration of total zinc in discharges to storm sewers to 40 µg/L (City of Toronto, 2010). In Montreal, the total extractable zinc level must be below 10 000 µg/L for discharge into the wastewater collection system and below 1000 µg/L for discharge into storm sewers or natural waterways (Communauté Métropolitaine de Montréal, 2012). In Vancouver any wastewater with more than 3000 µg/L of zinc needs a permit for discharging into a wastewater collection system (Metro Vancouver, 2007). Vancouver also has water quality objectives for the Burrard inlet. The maximum concentration objective is 95 µg/L, while the average concentration objective is 86 µg/L (Phippen, 2001). The regional municipality of Halifax sets a maximum total zinc concentration of 2000 µg/L in effluent discharged to wastewater collection or treatment systems (Halifax Regional Municipality, 2001). Halifax has a Harbour Water Quality Monitoring program that uses a guideline of 86 µg/L (AMEC Earth & Environmental, 2011).
7.2 Pertinent international risk management context
7.2.1 United States – Statutes
Over 717 zinc compounds are regulated in the USA under different statutes, with legal requirements ranging from reporting and notifications to restrictions. Of relevance to water releases is the Clean Water Act (CWA).
Under the CWA the discharge of oil or hazardous substances into or upon navigable waters as well as contiguous waters and areas of the United States is prohibited. Zinc acetate (CAS No. 557346), Zinc ammonium chloride (CAS No. 14639-97-5, 14639986, 52628-25-8), zinc borate (CAS No. 1332-07-6), zinc bromide (CAS No. 7699-45-8), zinc carbonate (CAS No. 3486-35-9), zinc chloride (CAS No. 7646-85-7), zinc cyanide (CAS No. 557-21-1), zinc fluoride (CAS No. 7783-49-5), zinc formate (CAS No. 557-41-5), zinc hydrosulfite (CAS No. 7779-86-4), zinc nitrate (CAS No. 7779-88-6), zinc phenolsulfonate (CAS No. 127-82-2), zinc phosphide (CAS No. 1314-84-7), zinc silicofluoride (CAS No. 16871-71-9), and zinc sulfate (CAS No. 7733-02-0) are all listed as hazardous substances under the CWA (US EPA, 2018a).
Considering that zinc and zinc compounds are listed on the Hazardous Substance List of Section 311 of the CWA, there are effluent guidelines in place in certain industries for their control (US EPA, 2018b). These industries include nonferrous metals forming and metal powders, electrical and electric components, battery manufacturing, metal molding and casting, coil coating, porcelain enameling, aluminum forming, copper forming, metal finishing, the centralized waste treatment, ore mining and dressing, transportation equipment cleaning, waste combustors, landfills, pesticide chemicals, iron and steel, non-ferrous metals manufacturing, steam electric power generating, rubber manufacturing, timber products processing and pulp, paper and paperboard point source categories (US EPA, 2018b).
Zinc and zinc containing substances are not on the 2014 TSCA Work Plan for Chemical Assessments and are therefore not being considered for further risk assessment by the agency (US EPA, 2014).
7.2.2 United States – Guidelines
Pursuant to Section 304(a) of the Clean Water Act (CWA), the United States Environmental Protection Agency (US EPA) publishes national recommended water criteria. The US EPA published an acute and chronic criterion of 120 µg/L for the protection of freshwater aquatic life. They established acute and chronic criteria of 90 µg/L and 81 µg/L, respectively, for the protection of saltwater life. Both the freshwater and marine criteria apply to a water hardness of 100 mg/L (US EPA, 2007). The US EPA also provides a human health consumption criterion of 7,400 µg/L for water and organisms and 26,000 µg/L for organisms only (US EPA, 2017). There is no maximum drinking water contaminant level for zinc in the National Primary Drinking Water Regulations, which are for contaminants that pose a risk for human health consumption and are legally enforceable. However, the Secondary Drinking Water Standards, which are to assist public water systems in managing their drinking water for aesthetic considerations and are not enforceable, has set a concentration limit of 5,000 µg/L for zinc (US EPA, 2012).
Some states have also published their own guidelines. For example, Minnesota has established a chronic standard of 106 µg/L and an acute standard of 117 µg/L in state waters based on a hardness of 100 mg/L (Minnesota Pollution Control Agency, 2016). New York uses equations based on water hardness as well to determine its state freshwater values, listing a chronic equation of e0.85 (ln (ppm hardness)) + 0.5 and an acute equation of 0.978e0.8473 (ln (hardness)) + 0.8604. For saline environments, it has an acute value of 95 µg/L and a chronic value of 66 µg/L (New York State Department of Environmental Conservation, 2017). Washington State uses equations based on water hardness to provide criteria for zinc concentrations in state freshwaters as well with an acute criterion of ≤ 0.978e0.8473(ln(harness)) + 0.8604 and chronic criterion of ≤ 0.986e0.8473(ln(harness)) + 0.7614. Its acute (90 µg/L) and chronic (81 µg/L) marine criteria match those of the current US guidelines. Washington also provides a human health consumption criterion of 2,300 µg/L for water and organisms and 2,900 µg/L for organisms only. (Washington State, 2016)
7.2.3 European Union – Statutes
In the European Union, some form of risk management exists or is being recommended for 2 zinc-containing substances.
Pentazinc chromate octhydroxide (CAS No. 49663-84-5) and Potassium hydroxyoctaoxodizincatedichromate (CAS No. 11103-86-9) have been identified by the European Union as Substances of Very High Concern (SVHC) for their carcinogenicity. As a result, these substances have been listed on both the Candidate List and the Authorisation List of the regulation on Registration, Evaluation, Authorisation and Restriction of Chemicals (ECHA, 2018b; ECHA, 2018a). Being listed on the Candidate List may imply legal obligations for producers, importers, and suppliers of those substances, while being listed on the Authorization List means that these substances cannot be placed on the market or used after a given date unless an authorisation is granted for their specific use, or the use is exempted from authorisation (ECHA, 2018c).
Under REACH, some zinc substances are restricted. Restricted substances (on their own, in a mixture or in an article) are substances for which manufacture, placing on the market or use is limited or banned in the European Union. Gallium zinc triarsenide (CAS RN 98106-56-0); trizinc diarsenide (CAS RN 12006-40-5); zinc diarsenide (CAS RN 12044-55-2); zinc aresenate (CAS 13464-44-3); silicic acid (H4SiO4), zinc salt (1:2), arsenic and manganese-doped (CAS RN 68611-46-1); cadmium zinc sulfide yellow (CAS RN 8048-07-5); cadmium zinc sulfide (CAS RN 12442-27-2); cadmium zinc lithopone yellow (CAS RN 90604-89-0); leach residues, zinc ore-calcine, cadmium copper ppt. (insoluble material precipitated by hydrolysis during hydrometallurgical treatment of crude zinc sulfate solution, CAS RN 91053-46-2); leach residues, zinc refining flue dust, cadmium-thallium ppt. (sponge produced by leaching and precipitating cadmium and thallium fumes and flue dusts from lead/zinc smelting operations, CAS RN 92257-11-9); and zinc bis(pentachlorophenolate) (CAS RN 2917-32-0) are all restricted (ECHA, 2018d).
7.2.4 European Union – Guidelines
In 2008, the European Union published Directive 2008/105/EC on Environmental Quality Standards. Annex I of the directive establishes limits on concentrations of certain pollutants in surface waters. Annex II lists the priority substances in the field of water policy. None of the targeted pollutants are zinc containing substances (European Commission, 2008). A proposal submitted in January 2012 to amend Directives 2000/60/EC and 2008/105/EC with regards to priority substances in the field of water policy does not include any zinc containing substances either (European Commission, 2012).
8. Next steps
8.1 Public comment period
Industry and other interested stakeholders are invited to submit comments on the content of this Risk Management Scope or other information that would help to inform decision-making (such as outlined in sections 3.2 or 3.3). Please submit additional information and comments prior to August 28, 2019. The Risk Management Approach document, which will outline and seek input on the proposed risk management instrument(s), will be published at the same time as the final Screening Assessment Report. At that time, there will be further opportunity for consultation.
Comments and information submissions on the Risk Management Scope should be submitted to the address provided below:
Program Development and Engagement Division
Environment and Climate Change Canada
Gatineau, Québec K1A 0H3
Telephone: 1-800-567-1999 (in Canada) or 819-938-3232
Companies who have a business interest in zinc and soluble zinc compounds are encouraged to identify themselves as stakeholders. The stakeholders will be informed of future decisions regarding zinc and soluble zinc compounds and may be contacted for further information.
8.2 Timing of actions
Electronic consultation on the draft Screening Assessment Report and Risk Management Scope: June 29, 2019 to August 28, 2019.
Submission of public comments, additional studies and/or information on zinc and its compounds: on or before August 28, 2019.
Consultation on the proposed instrument, if required: 60-day public comment period starting upon publication of each proposed instrument(s)
Publication of the final instrument, if required: at the latest, 18-month from the publication of each proposed instrument(s)
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Annex A. List of zinc-containing substances that were identified for further action during categorization
|CAS RNa||DSL or R-ICL Chemical Name||Substance Category||Inventory|
|127-82-2||Benzenesulfonic acid, 4-hydroxy-, zinc salt (2:1)||Organic-metal salt||DSL|
|136-23-2||Zinc, bis(dibutylcarbamodithioato-S,S’)-, (T-4)-||Organometallics||DSL|
|136-53-8||Hexanoic acid, 2-ethyl-, zinc salt||Organic-metal salt||DSL|
|155-04-4||2(3H)-Benzothiazolethione, zinc salt||Organic-metal salt||DSL|
|546-46-3||1,2,3-Propanetricarboxylic acid, 2-hydroxy-, zinc salt (2:3)||-||R-ICL|
|556-38-7||Pentanoic acid, zinc salt (2:1)||-||R-ICL|
|557-05-1||Octadecanoic acid, zinc salt||Organic-metal salt||DSL|
|557-07-3||9-Octadecenoic acid (Z)-, zinc salt||Organic-metal salt||DSL|
|557-08-4||10-Undecenoic acid, zinc salt||Organic-metal salt||DSL|
|557-34-6||Acetic acid, zinc salt||Organic-metal salt||DSL|
|1314-13-2||Zinc oxide (ZnO)||Inorganics||DSL|
|1314-22-3||Zinc peroxide (Zn(O2))||Inorganics||DSL|
|1314-84-7||Zinc phosphide (Zn3P2)||-||R-ICL|
|1314-98-3||Zinc sulfide (ZnS)||Inorganics||DSL|
|1345-05-7||C.I. Pigment White 5||UVCBs-inorganic||DSL|
|1434719-44-4||Protein hydrolyzates, saccharomyces cerevisiae zinc complexes||-||NFC|
|2452-01-9||Dodecanoic acid, zinc salt||Organic-metal salt||DSL|
|3486-35-9||Carbonic acid, zinc salt (1:1)||Inorganics||DSL|
|36393-20-1||Zincate(2-), bis[L-aspartato(2-)-.kappa.N,.kappa.O1]-, dihydrogen, (T-4)-||-||NFC|
|4259-15-8||Zinc, bis[O,O-bis(2-ethylhexyl) phosphorodithioato-S,S’]-, (T-4)-||Organometallics||DSL|
|5970-45-6||Acetic acid, zinc salt, dihydrate||Organic-metal salt||DSL|
|7446-19-7||Sulfuric acid, zinc salt (1:1), monohydrate||Inorganics||DSL|
|7446-20-0||Sulfuric acid, zinc salt (1:1), heptahydrate||Inorganics||DSL|
|7446-26-6||Diphosphoric acid, zinc salt (1:2)||Inorganics||DSL|
|7646-85-7||Zinc chloride (ZnCl2)||Inorganics||DSL|
|7733-02-0||Sulfuric acid, zinc salt (1:1)||Inorganics||DSL|
|7779-88-6||Nitric acid, zinc salt||Inorganics||DSL|
|7779-90-0||Phosphoric acid, zinc salt (2:3)||Inorganics||DSL|
|8011-96-9||Calamine (pharmaceutical preparation)||UVCBs-inorganic||DSL|
|8048-07-5||C.I. Pigment Yellow 35||UVCBs-inorganic||DSL|
|10139-47-6||Zinc iodide (ZnI2)||-||R-ICL|
|11103-86-9||Chromate(1-), hydroxyoctaoxodizincatedi-, potassium||Inorganics||DSL|
|12001-85-3||Naphthenic acids, zinc salts||UVCBs-organic-metal salts||DSL|
|12442-27-2||Cadmium zinc sulfide ((Cd,Zn)S)||Inorganics||DSL|
|13189-00-9||2-Propenoic acid, 2-methyl-, zinc salt||Organic-metal salt||DSL|
|13463-41-7||Zinc, bis(1-hydroxy-2(1H)-pyridinethionato-O,S)-, (T-4)-||Organometallics||DSL|
|13530-65-9||Chromic acid (H2CrO4), zinc salt (1:1)||Inorganics||DSL|
|13598-37-3||Phosphoric acid, zinc salt (2:1)||Inorganics||DSL|
|14324-55-1||Zinc, bis(diethylcarbamodithioato-S,S’)-, (T-4)-||Organometallics||DSL|
|14726-36-4||Zinc, bis[bis(phenylmethyl)carbamodithioato-S,S’]-, (T-4)-||Organometallics||DSL|
|15337-18-5||Zinc, bis(dipentylcarbamodithioato-S,S’)-, (T-4)-||Organometallics||DSL|
|15454-75-8||Zinc, bis(5-oxo-L-prolinato-.kappa.N1,.kappa.O2)-, (T-4)-||-||R-ICL|
|16260-27-8||Tetradecanoic acid, zinc salt||Organic-metal salt||DSL|
|16283-36-6||Zinc, bis(2-hydroxybenzoato-O1,O2)-, (T-4)-||Organometallics||DSL|
|16871-71-9||Silicate(2-), hexafluoro-, zinc (1:1)||Inorganics||DSL|
|17949-65-4||Zinc, bis(2-pyridinecarboxylato-.kappa.N1,.kappa.O2-, (T-4)-||-||R-ICL|
|19210-06-1||Phosphorodithioic acid, zinc salt||Inorganics||DSL|
|20427-58-1||Zinc hydroxide (Zn(OH)2)||Inorganics||DSL|
|24308-84-7||Benzenesulfinic acid, zinc salt||Organic-metal salt||DSL|
|24887-06-7||Zinc, bis(hydroxymethanesulfinato-OS,O1)-, (T-4)-||Organometallics||DSL|
|27253-29-8||Neodecanoic acid, zinc salt||Organic-metal salt||DSL|
|28016-00-4||Naphthalenesulfonic acid, dinonyl-, zinc salt||Organic-metal salt||DSL|
|28629-66-5||Zinc, bis(O,O-diisooctyl phosphorodithioato-S,S’)-||Organometallics||DSL|
|37300-23-5||C.I. Pigment Yellow 36||UVCBs-inorganic||DSL|
|38714-47-5||Zinc(2++), tetraammine-, (T-4)-, carbonate (1:1)||Inorganics||DSL|
|40861-29-8||Carbonic acid, ammonium zinc salt (2:2:1)||Inorganics||DSL|
|49663-84-5||Zinc chromate hydroxide (Zn5(CrO4)(OH)8)||Inorganics||DSL|
|50922-29-7||Chromium zinc oxide||UVCBs-inorganic||DSL|
|61617-00-3||2H-Benzimidazole-2-thione, 1,3-dihydro-4(or 5)-methyl-, zinc salt (2:1)||Organic-metal salt||DSL|
|68457-79-4||Phosphorodithioic acid, mixed O,O-bis(iso-Bu and pentyl) esters, zinc salts||UVCBs-organic-metal salts||DSL|
|68611-70-1||Zinc sulfide (ZnS), copper chloride-doped||UVCBs-inorganic||DSL|
|68649-42-3||Phosphorodithioic acid, O,O-di-C1-14-alkyl esters, zinc salts||UVCBs-organic-metal salts||DSL|
|68784-31-6||Phosphorodithioic acid, mixed O,O-bis(sec-Bu and 1,3-dimethylbutyl) esters, zinc salts||UVCBs-organic-metal salts||DSL|
|68918-69-4||Petrolatum (petroleum), oxidized, zinc salt||UVCBs-organic||DSL|
|68988-45-4||Phosphorodithioic acid, mixed O,O-bis(2-ethylhexyl and iso-Bu and pentyl) esters, zinc salts||UVCBs-organic-metal salts||DSL|
|73398-89-7||Xanthylium, 3,6-bis(diethylamino)-9-[2-(methoxycarbonyl)phenyl]-, (T-4)-tetrachlorozincate(2-) (2:1)||Organic-metal salt||DSL|
|84605-29-8||Phosphorodithioic acid, mixed O,O-bis(1,3-dimethylbutyl and iso-Pr) esters, zinc salts||UVCBs-organic-metal salts||DSL|
|85940-28-9||Phosphorodithioic acid, mixed O,O-bis(2-ethylhexyl and iso-Bu and iso-Pr) esters, zinc salts||UVCBs-organic-metal salts||DSL|
|102868-96-2||Zinc, bis[N-(acetyl-.kappa.O)-L-methioninato-.kappa.O]-, (T-4)-||-||R-ICL|
|113706-15-3||Phosphorodithioic acid, mixed O,O-bis(sec-Bu and isooctyl) esters, zinc salts||UVCBs-organic-metal salts||DSL|
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