Publication Summary

Eighteen fish tissue samples were collected from six sites in September 1993 for the Washington State Pesticide Monitoring Program. Samples were analyzed for 43 target pesticides and breakdown products, and seven polychlorinated biphenyls (PCBs). Thirty-four of the target pesticides were chlorinated insecticides or their breakdown products, five were organophosphorus insecticides, two were chlorinated herbicides, and two were chlorinated fungicides. Total lipid content was also determined for each sample.

Eighteen fish tissue samples were collected from six sites in September 1993 for the Washington State Pesticide Monitoring Program. Samples were analyzed for 43 target pesticides and breakdown products, and seven polychlorinated biphenyls (PCBs). Thirty-four of the target pesticides were chlorinated insecticides or their breakdown products, five were organophosphorus insecticides, two were chlorinated herbicides, and two were chlorinated fungicides. Total lipid content was also determined for each sample.

A total of 20 pesticides and breakdown products, and three PCBs (Aroclor equivalents), were detected in fish tissue samples. The majority of compounds identified were DDT, chlordane, or their metabolites. Only three of the detected pesticides, DCPA (Dacthal), ethion, and endosulfan sulfate (a breakdown product of endosulfan), are currently registered for use in Washington. A breakdown product of DDT, 4,4'-DDE, was the only target analyte detected at all sites. Other frequently detected compounds were 4,4'-DDD, 4,4'-DDT, cis- and trans-chlordane, and PCB-1260 and -1254. The most commonly detected commercially formulated pesticide was chlordane. Other formulated pesticides frequently found in fish tissue were 4,4'-DDT, hexachlorobenzene, and dieldrin.

Results were compared to USEPA screening values, proposed wildlife criteria, and to 85th percentiles calculated from statewide data. In fillet samples from the Walla Walla River, screening values were exceeded for total DDT (t-DDT), t-chlordane, dieldrin, heptachlor epoxide, hexachlorobenzene, and t-PCBs. Concentrations of t-DDT, dieldrin, and t-PCBs from the Walla Walla River, and t-PCBs from the Spokane River, were substantially higher than screening values. Wildlife criteria were exceeded for DDE, t-DDT, and t-PCBs in whole-fish samples from the Walla Walla and Wenatchee Rivers. Total PCBs were also above criteria in samples from Vancouver Lake and the Spokane River. Concentrations of t-DDT, t-chlordane, dieldrin, hexachlorobenzene, lindane, heptachlor epoxide, and t-PCBs in samples from the Walla Walla River, and t-PCBs in samples from the Wenatchee, Chehalis, and Spokane Rivers, and Vancouver Lake were above the state 85th percentile. Some piscivorous wildlife within the Walla Walla, Wenatchee, and Spokane River basins may be at risk from consumption of contaminated fish.

Link to EIM data for User Study ID WSPMP93T