State of Environment Reporting

Persistant Chemical in Wildlife in British Columbia

Contaminants in Great Blue Heron Eggs (mg/kg)

SOURCE: Environment Canada, Canadian Wildlife Service, 2000.

Persistent chemicals, such as PCBs and DDE, circulate in the environment for decades or centuries before breaking down. They accumulate in the fatty tissue of exposed organisms and increase in concentration as they rise through the food chain. The Great Blue Heron is an excellent indicator species for marine, estuarine and freshwater environments. The level of PCBs in Great Blue Heron eggs from the University of British Columbia (UBC) colony has decreased by 85% since 1977, when PCB manufacturing was terminated in North America. The level of DDE, a byproduct of the now-banned pesticide DDT, has decreased by 83% since 1977.