The exposure of aquatic life to organochlorine contaminants has been investigated during the past two decades because of human and ecosystem health concerns related to the bioaccumulation of hazardous, lipophilic substances. The toxic effects of polychlorodibenzo-12-dioxins and polychlorinated biphenyls (PCBs) are well known, and recent evidence also suggests that low level exposure to lipophilic organochlorines may interfere with normal development during sensitive early life history stages (Hileman 1993). As the use of lipophilic organochlorines, such as DDT, in third world countries continues and with the purported global cycling (Bidleman and Olney 1974; Tanabe et al. 1983) and food chain accumulation (Thomann and Connoly 1984, Thomann 1989) of persistent organochlodnes, the occurrence of these compounds in aquatic organisms is a critical global environmental issue. An understanding of the fate of organochlorines in the environment clearly remains an extremely important subject related to water quality.

The U.S. Geological Survey (USGS) has recently gained congressional approval in the United States to track nation wide trends in water quality through the establishment of the National Water Quality Assessment Program (NAWQA). Among the goals defined by NAWQA, aquatic organisms, including fish, shellfish, and plants, collected from major drainage basins will be analyzed for, along with other contaminants, polychlorinated biphenyls (PCBs), organochlorine insecticides, and chlorobenzenes (Crawford and Luoma 1992). The purpose of this report is to present quality assurance data obtained from the development of a PCB, chlorobenzene, and organochlorine insecticide tissue analysis method in support of NAWQA and other large-scale water quality programs conducted
through our laboratory.