Polychlorinated biphenyl (PCBs) compounds are a class of legacy organochlorines that share a structural similarity and toxic mode of action with the insecticides Mirex and Toxaphene, widely-used insecticides. Those organic contaminants are known to exert multiple toxic effects throughout the food web in lakes. PCBs were widely used as coolants and insulating fluids in transformers, capacitors and electric motors, and in a variety of other industrial uses, but their manufacture and importation to North American ended in 1977-1980. As with other restricted legacy organochlorines, most PCB compounds are extremely resistant to degradation and persist for decades in the environment. Like methylmercury, many PCB compounds bioaccumulate rapidly through food chains, resulting in restrictions on fish consumption and concerns for wildlife health.1
Effects of exposure to PCBs
Adverse health effects associated with PCB exposure include
- Disruption of reproductive function
- Neurobehavioral and developmental deficits in children
- Systemic effects such as liver disease, diabetes, and effects on thyroid and immune systems
- Increased cancer risks.2
Mapping Total PCBs as a Great Lakes stressor
We mapped surficial sediment total PCB concentration from Environment Canada (3). Data were kriged using ArcGIS algorithms with a 5-point neighborhood. The point data values range from zero to 255 ppm. The highest values are concentrated in Lake Ontario, the western and central basins of Lake Erie and southeast Lake Michigan.
Spatial distribution of total PCBs as a stressor in the Laurentian Great Lakes. (Inset: Western Lake Ontario).