What is Arsenic?
Arsenic is a metal, and is found throughout the earth’s crust, most often as arsenic sulphide or as metal arsenates and arsenides. In fact, arsenic is found in trace amounts in all living matter. In commercial and industrial use, arsenic is used in the manufacture of transistors, lasers and semi-conductors, as well as in the processing of glass, pigments, textiles, paper, metal adhesives, ceramics, wood preservatives, ammunition and explosives. Arsenic is also used to a limited extent in pesticides, feed additives and pharmaceuticals, including veterinary drugs.

How does Arsenic enter our water?
Most often, arsenic enters water naturally as the earth’s minerals and ores dissolve. It also enters water from industrial effluents and deposits from air. The natural background level of arsenic in surface waters is usually low, ranging between 1 and 2 micrograms per litre of water. The level of arsenic in groundwater is slightly higher, though this depends on the geology in a given region and the presence of human activity such as mining.

How does Arsenic affect human health?
Arsenic in drinking water is absorbed by the body, with the bloodstream taking it to various organs. The highest levels are found in nails and hair, which accumulate arsenic over time. Your body gets rid of arsenic mostly through the urine with smaller amounts removed from the body through the skin, hair, nails and sweat.

The International Agency for Research on Cancer considers arsenic a human carcinogen. Years of consumption of drinking water containing arsenic at levels close to or higher than the guideline value has been found to increase the risk of skin cancer and tumours of the bladder, kidney, liver and lung.

Long-term exposure over years to higher levels of arsenic in drinking water may also cause: thickening and discoloration of the skin; nausea and diarrhoea; decreased production of blood cells; abnormal heart rhythm and blood vessel damage; and numbness in the hands and feet.

Short-term exposure (days/weeks) to very high levels of arsenic in drinking water can result in abdominal pain, vomiting and diarrhoea; muscular cramping or pain; weakness and flushing of skin, skin rash; numbness, burning or tingling sensation or pain in extremities (hands and feet); thickening of the skin of the palms of the hands and soles of the feet; and deterioration of motor and sensory responses.

How does Arsenic affect the aquatic environment?
Depending on the amount, arsenic can be toxic to freshwater fish, invertebrates, and aquatic plants. At low amounts it can slow aquatic plant life, and at higher concentrations it is lethal.

What are the Arsenic guidelines?
The Federal-Provincial-Territorial Committee on Drinking Water has established a guideline for arsenic in drinking water, as an Interim Maximum Acceptable Concentration, at 25 micrograms per litre of water. The guideline is designated as interim because of the limitations in the treatment technology at the time.

• Drinking Water Guidelines

In tissue residue, the guideline for fish and fish products is 3.5 micrograms per kilogram of tissue.

• Canadian Guidelines for Chemical Contaminants and Toxins in Fish and Fish Products

The Canadian Water Quality Guideline for the Protection of Aquatic Life is 5 micrograms per litre of water. An interim Canadian Sediment Quality Guideline for the Protection of Aquatic Life of 5.9 milligrams per kilogram of sediment has been developed to protect bottom dwelling aquatic life since arsenic is most likely to settle in the bottom sediments.

• Canadian Water Quality Guidelines for the Protection of Aquatic Life:
  • for water
  • for sediment

What can individuals do to help?
To help avoid arsenic from reaching our water supply:

• Be aware of product contents. Many chemicals commonly used around the home contain arsenic, and are toxic to humans and the environment. Select less toxic alternatives or use non-toxic substitutes wherever possible.
• Properly dispose of substances containing arsenic at hazardous waste collection centres . Do not pour them down the drain, on the ground, or in the sewer. Pouring chemicals in these areas may disrupt septic systems or contaminate water supplies.
• Properly dispose of Copper Chromated Arsenate (CCA) treated wood and sawdust. CCA is commonly used as a wood preservative (The copper in CCA gives the green colour to treated wood). Do not burn sawdust or any portion of the treated wood. Do not saw or plane in poorly ventilated areas. Do not breath sawdust. See other recommendations from the Pest Management Regulatory Agency on the Update of the re-evaluation of CCA treated wood in Canada.