Toxic Chemical Compounds: Easy to Find, Hard to Destroy

The most persistent toxic chemicals in the Spokane River watershed are called polychlorinated biphenyls (PCBs). PCBs are human-made, chlorinated chemical compounds. They are found in plasticizers, paint additives, adhesives, inks, lubricants, and hydraulic fluids. These chemicals are quickly accumulated by aquatic organisms and, through the food chain, by humans.

PCBs are a demonstrated neurotoxin. They have been shown to cause cancer in animals, and can also cause adverse effects on the immune system, reproductive system, nervous system, and endocrine system.The World Health Organization classifies PCBs as established human carcinogens.


PCBs were first manufactured in the U.S. in 1929, marketed by Monsanto under the brand name Aroclors. In 1977, however, production of all PCBs was banned by the EPA because of concerns about toxicity and persistence in the environment. The catch was that PCB-containing materials still in service at the time of the ban were not required to be removed from use, and therefore, some are still in use. Additionally, some types of PCBs are inadvertently produced in the manufacture of pigments (these are called “iPCBs”). Because of this, they still show up in some paints and dyes, most commonly in yellows and bright greens. Products including tinted newsprint, packaging, and yellow street paint often contain small amounts of PCBs.

PCBs continue to be a problem around many areas of the country. As of 1998, 37 states had issued 679 fish advisories for PCBs. Here in the Pacific Northwest, the state of Oregon has issued a statewide advisory on PCBs in fish. PCBs of up to 90 parts per billion (ppb) in fish have been observed in the Willamette River in Portland. Seattle’s lower Duwamish River industrial waterway have found fish with concentrations as high as 159 ppb. For comparison, 1999 Rainbow fillet concentrations from the Spokane River range from 50 to 1, 610ppb, with an average of 279 ppb. (link to Ecology study)

Some PCB FAQs:

How do PCBs get into the Spokane River?

Due to their widespread use, PCBs are found basically everywhere,indoors and outdoors. Industrial discharges, past disposal practices, contaminated groundwater, wastewater treatment plants, and stormwater runoff are all sources of PCBs in the Spokane River. Over the years, municipal wastewater treatment plants, stormwater out falls, and unknown spills also may have discharged trace amounts of this contaminant. PCBs deposited in sediments from historical discharges also find their way into fish from the food web.

How can PCBs in the Spokane River be reduced?

To meet PCB standards for the river and further reduce PCBs found in fish, industrial and municipal dischargers between the Idaho border and Lake Spokane (formerly Long Lake) will need to significantly reduce the amount of PCBs in their waste water and stormwater. Additionally, non-point pollution sources such as stormwater runoff and groundwater contaminated from cleanup sites will need to be controlled, and the EPA will need to reform its Toxics Substances Control Act (TSCA), which allows up to 50 ppm into our area by way of consumer products. Reductions in PCBs also are needed on the Idaho side of the border.

What are the ecological and health problems associated with high PCB concentrations?

PCBs are highly fat-soluble and are quickly accumulated by aquatic organisms and accumulated through the foodchain, including humans. They have been demonstrated to cause a variety of adverse health effects in animals: cancer, as well as anumber of serious non-cancer health effects, in animals, such as effects on the immune system, reproductive system, nervous system, and endocrine system. Studies in humans also indicate potential carcinogenic and non-carcinogenic effects of PCBs. The different health effects of PCBs may be interrelated; alterations in one system may have significant implications for the other systems of the body.

PCBs bioaccumulate in fish tissue, and in other animals that consume fish and food sources that contain PCBs. Typically the older and/or larger the fish, the more PCBs are stored in its flesh. They also biomagnify up the food chain so that larger prey species that eat smaller organisms end up with a larger burden of PCBs. Because of this, concentrations of PCBs in aquatic organisms may be 2,000 to more than a million times higher than the concentrations found in the surrounding waters.

What is the distribution of PCBs throughout the Spokane River Watershed?

PCBs in our water increase downstream from the Idaho border to the Long Lake Dam, with hot spots between the Sullivan Road area and the Green Street Bridge in Spokane. Sampling suggests that PCB levels in some fish may have been improving over the last two decades. However, the concentrations of PCBs in our water are significantly higher than state and Spokane Tribal water-quality standards.

The public was first notified about PCBs in Upper Spokane River fish in 1995, as a result of the analysis of samples collected in 1993 and 1994.

Map of PCB

Further Reading

This project is supported by funds from the Washington State Department of Ecology.

Bunker Hill
Midnite Mine
Storm Water
Dischargers and Waste Water
Washington State Polluted Waters
Fish Consumption Advisory
Beach Cleanup
Rathdrum Aquifer
Coeur d'Alene Lake
What you can do