PCB Checklist

• Widespread in the estuary, both geographically and in the food chain
• Released through accidental spills of PCB-containing fluids
• Bioaccumulative
• Similar to PBDE flame retardants in chemical structure and sublethal effects
• Carcinogenic to people, sublethal effects on salmon health
• Still used in electrical equipment

What Are They?

Polychlorinated biphenyls, or PCBs, are stable, flame-resistant chemicals that were manufactured for use in consumer products (lubricants, paints, pesticides, etc.) and as insulators and cooling compounds in electrical equipment. They come in 209 different forms, or congeners, which vary in their degree of toxicity and carcinogenicity. The most toxic PCBs are structurally similar to dioxins.

PCBs do not degrade readily or dissolve in water. Instead, they tend to accumulate in sediments and the body fat of living organisms. Over time, PCBs biomagnify up the food chain to top predators, including humans.

The manufacture of PCBs was banned in the United States in 1979, but their use is still allowed in closed electrical equipment (transformers, capacitors, ballasts, etc.).

PCBs in the Estuary

PCBs have been found in river water samples and in the tissue and stomach contents of juvenile salmon at sites throughout the Columbia River estuary, from just below Bonneville Dam to the river’s mouth near Astoria (Lower Columbia River Estuary Partnership 2007).

Impacts in the Environment

Exposure to PCBs can kill salmon outright. Sublethal effects include immune suppression (which increases disease-related mortality), hormone disruption, and disrupted reproduction.
PCB concentrations in some juvenile salmon in the estuary are at or above the threshold level (2,400 nanograms per gram lipid) for health effects such as delayed mortality, biochemical alterations, and immune dysfunction (Lower Columbia River Estuary Partnership 2007).

Sources of Exposure

PCBs have been released to the environment unintentionally, sometimes through spills. They can be found in the air, soil, sediment, and water, and in fish, wildlife, and people.
In the Columbia River estuary, juvenile salmon are known to be exposed to PCBs through their prey, hatchery feed, river water, suspended sediment, and—at some sites—bed sediment (Lower Columbia River Estuary Partnership 2007).

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ⁱ Lower Columbia River Estuary Partnership. 2007. Lower Columbia River and Estuary Ecosystem Monitoring: Water Quality and Salmon Sampling Report.