Canadian Environmental Health Atlas

Understanding Our Environment is Key to Promoting Health and Preventing Disease

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Chemical Contaminants

Chemical Contaminants

Our bodies are made up of about 70% water. Most of our fluid intake comes from consuming water and drinks made with water1. Because many contaminants, including lead and arsenic, are soluble in water, we can be exposed to toxins when we drink water.

The concentration of the toxin (i.e. quantity in water) and the dose (i.e. amount of water ingested) determine whether a person will experience harmful effects. Ingestion is the most common route of exposure, though some toxins can be absorbed through the skin or by inhalation while taking a shower.

Toxins can contaminate water as a result of both human activities and natural processes. Ground and surface water may be contaminated by industrial discharges, leaching from landfills, or the application of pesticides. Chemicals found naturally in soils and rock, like arsenic and manganese, may leach into ground and surface water. Whatever the source, these contaminants can have adverse health effects, particularly when people are exposed to high concentrations of a toxin. For example, exposure to high levels of lead in drinking water, which is usually from contact with lead-containing water mains, service lines, or fixtures, is associated with intellectual deficits in children and cardiovascular disease in adults. Exposure to high levels of arsenic is associated with increased risk of skin diseases and cancer.