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.

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:

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:

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%).

Map showing the distribution of arsenic releases in Canada in 2020.
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).

Breakdown by province of total arsenic releases in 2020
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Breakdown of total arsenic releases in 2020 in tonnes
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:

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.

Total releases of arsenic (tonnes) between 2010 and 2020
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Total releases of arsenic since 2010 in tonnes
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%.

Breakdown by media of arsenic releases
Long description
Breakdown of arsenic releases per media since 2010
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.

Releases of arsenic to air (tonnes) between 2010 and 2020
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Releases of arsenic to air in tonnes since 2010
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.

Releases of arsenic to land (tonnes) between 2010 and 2020
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Releases of arsenic to land in tonnes since 2010
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.

Releases of arsenic to water (tonnes) between 2010 and 2020
Long description
Releases of arsenic to water bodies in tonnes since 2010
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.

On-site disposals or arsenic in TWR (tonnes) between 2010 and 2020
Long description
Waste rock and tailings disposed of on site since 2010 in tonnes
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.

Off-site disposals of arsenic excluding TWR (tonnes) between 2010 and 2020
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Off-site disposals in tonnes excluding TWR since 2010
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.

Off-site disposals of arsenic in TWR (tonnes) between 2010 and 2020
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Off-site disposals of TWR in tonnes since 2010
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.

Off-site transfer of arsenic for recycling (tonnes) between 2010 and 2020
Long description
Off-site transfer of arsenic for recycling in tonnes since 2010
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:

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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