Environmental Trends 2007

Contaminants

Overview - What is Happening?

Over 23,000 chemicals and other substances are in use in Canada. Some are intended for controlled use (e.g., pesticides and water purification chemicals), some are released into the environment as by-products (e.g., from burning wood or petroleum products), and some are accidentally released through spills and leaks.

Photo credit: Ministry of Transportation

Most of the following indicators concern persistent organic pollutants (POPs). These are mostly industrial chemicals or by-products of incineration; some were used as insecticides. The main groups of POPs discussed in this report include PCBs, doxins and furans, PBDEs and DDT. POPs persist for a very long time in the environment and have a variety of toxic effects, including disruption of the hormone and immune systems of mammals. When organisms contaminated with these chemicals are eaten by other animals, the compounds become more concentrated in the bodies of predators, often reaching high levels in top predators.

• Total on-site releases and disposal of toxic substances in B.C. remained about the same for 2002-2005 (four years is not enough to show trends). Pollutants released in the largest quantity include hydrogen sulphide, sulphur dioxide, ammonia and methanol.

• Since 1990, the levels of dioxins (by-products of pulp bleaching processes) in pulp and paper mill effluent have dropped to undetectable levels. Levels in sediments and in crabs living near mill outfalls, have also declined steeply. The results are correlated with changes in regulations and pulp mill technology that were made to address the issue.

• British Columbia is making progress cleaning up contaminated sites. As of 2006, 71 per cent of the approximately 6800 contaminated sites registered in the provincial database have been remediated or are in some stage of the process.

• Monitoring for POPs in bird eggs in B.C. shows that concentrations of PCBs, dioxins, furans and organochlorine pesticides have decreased over the last 30 years. At the same time, there has been a rapid increase in concentrations of PBDEs, which are flame retardant chemicals widely used in consumer goods.

• Research on POPs in marine mammals on the B.C. coast shows that tissues of killer whales are contaminated with PCBs and PBDEs. Contaminants in the tissues of harbour seals differ regionally: Puget Sound seals have the highest concentrations, while Queen Charlotte Sound seals are least contaminated.

• Efforts to reduce pesticide use in landscaping have led to a substantial reduction in the quantity of pesticide use since 1991. Landscaping services in the Lower Mainland cut pesticide use in half between 1991 and 2004. By 2004, four of the six landscape pesticides of most concern in the Georgia Basin in 1991 were no longer in use.

For detailed information, including graph data, see In-Depth Report [pdf].