Canadian Environmental Protection Act: Priority Substances List: Arsenic and its compounds
Arsenic and its compounds
(Priority substances list assessment report)
At head of title: Canadian Environmental Protection Act.
Issued also in French under title: L'Arsenic et ses composés .
Includes bibliographical references.
DSS cat. no. En40-215/14E
1. Arsenic -- Toxicity testing.
2. Arsenic -- Environmental aspects.
3. Arsenic compounds -- Environmental aspects.
4. Environmental monitoring -- Canada.
I. Canada. Environment Canada. II. Canada.
Health and Welfare Canada. III. Series
TP245.A8A3 1993 669 '.75 C93-099516-3
Due to the nature of the available data, this assessment of "arsenic and its compounds" focuses on "arsenic and its inorganic compounds". Arsenic is present in the aquatic and terrestrial environments because of natural weathering and erosion of rock and soil, and human activities (including gold- and base-metal processing, the use of arsenical pesticides, coal-fired power generation and the disposal of domestic and industrial waste materials). The highest concentrations of arsenic and its inorganic compounds in the Canadian environment occur near active and abandoned gold- and base-metal mining and ore processing facilities, and in areas affected by the use of arsenical pesticides. Mean arsenic concentrations of up to 0.3 µg/m3 in air, 45 µg/L in surface waters, 100 to 5 000 mg/kg in sediments and 50 to 110 mg/kg in soils have been found near these sources in several regions of Canada; most (= 80%) of this arsenic is likely inorganic. In addition, an average of up to 35 mg inorganic As/kg (dry weight) may be present in the diet of fish, and 109 µg inorganic As/kg body weight per day may be present in the diet of fish-eating mammals near gold-mining areas in Canada. These concentrations of arsenic are high enough to cause, or to have the potential to cause, adverse effects in a variety of aquatic and terrestrial organisms. Canadians are exposed to inorganic arsenic in food, drinking water, soil and ambient air, with food representing the major source of intake. Exposure to arsenic may be elevated in populations residing in the vicinity of industrial and geological sources. Inorganic arsenic has been consistently demonstrated in numerous studies to cause cancer in humans exposed by both inhalation and ingestion. The group of inorganic arsenic compounds as a whole (since data do not permit an assessment of individual compounds within the group) is therefore considered to be a "non-threshold toxicant" (i.e., a substance for which there is believed to be some chance of adverse health effects at any level of exposure). For such substances, estimated exposure is compared to quantitative estimates of cancer potency to characterize risk and provide guidance for further action (i.e., analysis of options to reduce exposure). For inorganic arsenic, such a comparison suggests that the priority for analysis of options to reduce exposure would be moderate to high. Based on these considerations, the Ministers of the Environment and of National Health and Welfare have concluded that the current concentrations of inorganic arsenic in Canada may be harmful to the environment and may constitute a danger in Canada to human life or health. Therefore, “arsenic and its compounds” (as specified above) are considered to be "toxic" as interpreted under section 11 of the Canadian Environmental Protection Act (CEPA).