The National Pollutants Release Inventory: arsenic
Since 1993, the Government of Canada has collected data from certain Canadian facilities on pollutant releases to water, air, and land through the National Pollutant Release Inventory (NPRI). Facilities that meet the reporting thresholds or that carry out certain activities are required to report the quantities of each substance released.
The following map shows the locations of facilities that reported releases of arsenic to the NPRI in 2020.
Long description
Map showing the locations of facilities that reported releases of arsenic to the NPRI in 2020.
You can find the data used to create this map using our single year data tables.
In this overview on arsenic, you will learn about:
- the effects of arsenic on human health and the environment
- arsenic releases to air, water, and land, as well as on-site disposals and off-site transfers for recycling
- the pollution reduction and mitigation measures taken by industry and the Government of Canada
Background
Arsenic is a naturally occurring element that is used in a wide variety of industrial applications. However, it rarely exists in pure form. Arsenic generally combines with other elements to form various organic and inorganic compounds. For example, when arsenic is combined with carbon or hydrogen, it forms organic arsenic compounds. If it combines with oxygen, chloride or sulphur, it forms inorganic arsenic compounds. It is important to know that while organic arsenic is considered non-toxic, inorganic arsenic is toxic to human health.
Inorganic arsenic is on the List of Toxic Substances in Schedule 1 of the Canadian Environmental Protection Act, 1999 (CEPA) because it is a substance that is “entering or may enter the environment in a quantity or concentration that may have an immediate or long-term harmful effect on the environment or its biological diversity and constitute a danger in Canada to human life or health.”
Effects on human health
According to Health Canada studies, arsenic can enter the food supply through water, soil or air. For example, according to the Canadian Food Inspection Agency, inorganic arsenic is most often found in fruit juice and rice since it is naturally present in all plants. Organic arsenic is mainly detected in fish and shellfish, although the levels of arsenic in foods sold in Canada are generally low.
Inorganic arsenic compounds accumulate in human tissues through a process called bioaccumulation. Long-term exposure to high levels of inorganic arsenic is associated with an increased risk of cancer and other adverse health effects, such as:
- heart disease
- nausea and diarrhea
- numbness in the hands and feet
Effects on the environment
Arsenic is a tasteless and odourless natural element that is found widely in the earth’s crust. However, high levels of arsenic can cause numerous environmental and health impacts. The primary source of exposure is food, followed by water, soil, and air. When released into the environment, arsenic can cause reduction in growth and photosynthesis in plants, behavioural effects, death, and can adversely affect species reproduction.
Arsenic does not biomagnifyFootnote 1 in food chains as its effects are mostly concentrated near emission sources. When released to air, arsenic can also have adverse effects on small mammals.
In water, arsenic binds to sediments (e.g. iron oxides and clay) and can have chronic effects on freshwater benthic organisms, impacting the health of the watercourse.
Soil alteration and erosion associated with mining operations can result in groundwater contamination by arsenic.
After assessing the risks of arsenic, Health Canada established a water quality guideline of 0.010 milligrams per litreFootnote 2 for arsenic in drinking water. Fortunately, data indicates that arsenic levels in Canadian water are generally less than 0.005 parts per million (ppm).
In Canada, various levels of government have a role to play in maintaining water quality to ensure the public has access to clean drinking water. The guidelines and requirements related to water quality are therefore revised on a regular basis to take into account the latest research.
Where arsenic is released in Canada
The following map shows the distribution of arsenic releases in Canada in 2020. We observe that the highest reported releases were from Nunavut (50%), Québec (25%) and Ontario (10%).
Long description
Map showing the distribution of arsenic releases in Canada in 2020.
You can find the data used to create this map using our single year data tables.
Of the 296 facilities reporting arsenic releases in 2020 to the NPRI, Ontario has the most reporting facilities (85), followed by Québec (57), Alberta (50) and British Columbia (45).
Long description
Province | Quantity (tonnes) |
---|---|
Alberta | 466 |
British Columbia | 1,090 |
Manitoba | 1,625 |
New Brunswick | 854 |
Newfoundland and Labrador | 126 |
Nunavut | 14 |
Nova Scotia | 5,426 |
Nunavut | 33,311 |
Ontario |
6,776 |
Quebec | 16,552 |
Saskatchewan |
557 |
Reporting facilities
In 2020, facilities reported a total release of 47.8 tonnes of arsenic to air, water and Land combined. The majority of the arsenic released in that same year was 26.2 tonnes to air. A total of 12.6 tonnes was released to land and 9 tonnes to water. Among these releases, the mining and quarrying sector released a total of 15.6 tonnes of arsenic.
Facilities that report arsenic releases to the NPRI are part of the following key industrial sectors:
- mining and quarrying
- metal production, such as steel manufacturing, base metal smelting and gold extraction
- wood preservation
- energy production from fossil fuels, such as coal
In 2020, 96% (64,585 tonnes) of total arsenic releases reported to the NPRI belonged to the mining and quarrying sector, with a total of 97 reporting facilities. The total disposals or transfers for treatment and recycling for the mining and quarrying sector was 64,569.8 tonnes of arsenic in 2020. This is due to the fact that arsenic is generally found in gold, silver, nickel, copper and zinc ores. These “contaminated” minerals release arsenic when they are extracted from the earth’s crust during mining activities. Arsenic has also long been used as a pesticide and as a wood preservative for utility poles. For this reason, arsenic is often detected in agricultural fields, orchards and around hydroelectric lines.
Trends in arsenic releases over the last 10 years
This trend overview focuses on the quantities of arsenic reported to the NPRI since 2010. Until 2002, releases were reported to the NPRI in tonnes rather than kilograms.
Total arsenic releases reported to the NPRI and the number of reporting facilities have been increasing since 2010.
In the graph below, we note that the reported releases were relatively constant until 2018, when releases almost doubled from previous years. This upward trend in total arsenic releases continued in 2020. This is due to significant amounts of on-site tailings and waste rock disposals (TWR). Since mines calculate their arsenic amounts by multiplying the amount of waste generated by the measured concentration, releases vary greatly when concentrations change. However, the concentrations measured in the tailings are variable and do not have the same toxicity. For example, in 2020, the facility with the largest amount of releases reported average concentrations of 196 parts per million (ppm) in TWR, while the second facility measured an average of 1,093 ppm in TWR.
Long description
Year | Quantity |
Facilities |
---|---|---|
2010 | 17,978 | 280 |
2011 | 24,201 | 283 |
2012 |
20,795 | 287 |
2013 | 20,872 | 283 |
2014 | 20,176 | 289 |
2015 | 24,441 | 274 |
2016 | 23,075 | 277 |
2017 | 24,073 | 285 |
2018 | 31,752 | 288 |
2019 | 55,898 | 300 |
2020 | 67,515 | 296 |
Since many facilities report arsenic releases to the NPRI, let us examine the breakdown by media of releases to identify trends over time.
Since 2010, the category “on-site disposal of tailings and waste rock (TWR)” has accounted for 96% of arsenic releases reported to the NPRI, followed by off-site disposals excluding TWR with 2% and off-site transfers for recycling with 2%.
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Media | Quantity |
---|---|
Off-site disposal (excluding TWR) |
6,157 |
Off-site disposal of TWR |
60 |
On-site disposal (excluding TWR) |
1,739 |
On-site disposal (TWR) |
316,123 |
Off-site recycling |
5,375 |
Releases to air |
425 |
Releases to land |
104 |
Releases to water bodies |
368 |
Off-site transfers for treatment prior to final disposal (excluding TWR) |
425 |
Total releases
The graph below shows that releases to air in 2020 have decreased by almost half since 2010, despite a slight increase in the number of reporting facilities over time.
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Year | Quantity |
Facilities |
---|---|---|
2010 | 49 |
168 |
2011 | 37 |
163 |
2012 |
37 |
178 |
2013 | 37 |
186 |
2014 | 49 |
181 |
2015 | 47 |
175 |
2016 | 43 |
182 |
2017 | 36 |
187 |
2018 | 39 |
196 |
2019 | 26 |
205 |
2020 | 26 |
195 |
Releases of arsenic to land reported to the NPRI total a few tonnes and are trending downward. We note in the following graph that the years 2011, 2012, 2019 and 2020 have the highest amounts of arsenic reported to NPRI, which were from facilities in the mining and quarrying sector.
Long description
Year | Quantity |
Facilities |
---|---|---|
2010 | 4 |
22 |
2011 | 14 |
18 |
2012 |
19 |
16 |
2013 | 6 |
18 |
2014 | 9 |
13 |
2015 | 5 |
16 |
2016 | 4 |
17 |
2017 | 7 |
21 |
2018 | 9 |
16 |
2019 | 14 |
15 |
2020 | 13 |
19 |
The following graph shows arsenic releases to water since 2010. We observe that in 2014, releases were very high compared to other years due to a major accidental spill that affected several water bodies, including, Quesnel Lake, Polley Lake and Hazeltine Creek in British Columbia. Otherwise, releases have been consistent since 2010, despite the increasing number of facilities.
Long description
Year | Quantity |
Facilities |
---|---|---|
2010 | 11 |
139 |
2011 | 11 |
146 |
2012 |
11 |
156 |
2013 | 11 |
155 |
2014 | 269 |
155 |
2015 | 9 |
147 |
2016 | 10 |
148 |
2017 | 10 |
151 |
2018 | 9 |
146 |
2019 | 9 |
158 |
2020 | 9 |
160 |
Overall, there are declining trends in arsenic releases to water, air, and soil, demonstrating that the control measures put in place by industry and the Government of Canada are working.
On-site disposals
In 2020, 96% (66 482 tonnes) of the arsenic releases reported to the NPRI consisted of on-site disposals of tailings and waste rock (TWR).
The vast majority of arsenic releases are included in on-site tailings and waste rock from facilities. In the graph, we note that on-site disposals were constant until 2019, when they increased significantly despite the similar number of facilities. The highest arsenic disposals in 2019 and 2020 are due to about ten facilities that managed their tailings on-site.
Long description
Year | Quantity |
Facilities |
---|---|---|
2010 | 16,746 |
89 |
2011 | 22,734 |
93 |
2012 |
19,508 |
93 |
2013 | 19,722 |
89 |
2014 | 18,655 |
93 |
2015 | 22,962 |
87 |
2016 | 21,631 |
80 |
2017 | 22,738 |
90 |
2018 | 30,586 |
93 |
2019 | 54,471 |
101 |
2020 | 66,369 |
93 |
Off-site disposals
Starting in 2017, off-site disposals (excluding TWR) began to follow an apparent downward trend, despite some increase in the number of reporting facilities until 2019. A facility reporting the largest disposals in 2013 was phased out for final closure in 2019. The closure of a facility involves the management of residues remaining on the site, which can lead to the reporting of high quantities in subsequent years. In 2020, a total of 67 468 tonnes of arsenic were reported as disposals or transfers for treatment and recycling. Total off-site arsenic disposals were approximately 986 tonnes.
Long description
Year | Quantity |
Facilities |
---|---|---|
2010 | 338 |
94 |
2011 | 771 |
95 |
2012 |
715 |
93 |
2013 | 587 |
92 |
2014 | 678 |
98 |
2015 | 755 |
93 |
2016 | 648 |
92 |
2017 | 675 |
90 |
2018 | 542 |
97 |
2019 | 382 |
104 |
2020 | 67 |
97 |
Off-site disposals of TWR are very low and have a maximum of less than 30 tonnes for all facilities reporting to NPRI. The increase in 2015 came from a single facility located in Québec that transferred 25 tonnes for disposal.
Long description
Year | Quantity |
Facilities |
---|---|---|
2010 | 4 |
4 |
2011 | 7 |
4 |
2012 |
3 |
3 |
2013 | 2 |
2 |
2014 | 4 |
4 |
2015 | 29 |
5 |
2016 | 3 |
5 |
2017 | 2 |
4 |
2018 | 2 |
4 |
2019 | 2 |
4 |
2020 | 2 |
4 |
Off-site transfers of arsenic for recycling have been trending upward since 2010, following the increase in reporting facilities. Transfers for recycling increased in 2019 due to the reporting of two facilities (430 tonnes and 388 tonnes) that sent their TWR for recovery of metals and their compounds. These are the same two facilities that contributed the large amount of arsenic transfer for recycling in 2020 (447 tonnes and 415 tonnes). These two facilities account for 96% of arsenic transfers for recycling in 2019 and 2020.
Long description
Year | Quantity |
Facilities |
---|---|---|
2010 | 472 | 38 |
2011 | 401 | 36 |
2012 |
311 | 43 |
2013 | 308 | 38 |
2014 | 332 | 36 |
2015 | 468 |
41 |
2016 | 518 | 45 |
2017 | 434 |
40 |
2018 | 391 | 46 |
2019 | 853 | 50 |
2020 | 889 | 50 |
To learn more about tailings and waste rock, see the NPRI Sector Overview on Metal Ore Mining.
Pollution prevention activities and government measures
Since arsenic is listed as a toxic substance under CEPA, Environment and Climate Change Canada implements a number of mechanisms to manage the risks associated with arsenic releases to the environment, such as:
- new source emission guidelines for thermal electricity generation
- environmental code of practice for integrated steel mills and non-integrated steel mills
- notice requiring the preparation and implementation of pollution prevention plans in respect of inorganic arsenic compounds
- regulations, such as the Metal and Diamond Mining Effluent Regulations
- the Canadian Total Diet Study, an annual program that monitors the concentrations of arsenic in food (conducted by Health Canada and the Canadian Food Inspection Agency, in accordance with guidance from the World Health Organization)
Health Canada has set a maximum acceptable concentration of 0.010 milligrams per litre for arsenic in drinking water. The different levels of government are working together to manage the risks associated with this substance.
More information
If you would like more information on arsenic or any other substance tracked by the NPRI, please refer to the various online datasets, NPRI data search and other substance and industrial sector overviews.
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