Resource-management and regulatory agencies face many complex problems associated with the contamination of our air, land, water, and biological resources by an array of chemicals originating from agricultural, industrial, municipal, and residential sources. Some contaminants are toxic and can cause stress, injury, or death in exposed organisms. Methylmercury and polychlorinated biphenyls (PCBs) are of special concern because they readily accumulate in exposed organisms and can biomagnify to high concentrations in organisms near or at the top of food webs.

The pollution of aquatic and terrestrial environments with toxic contaminants can greatly diminish habitat suitability for biota. Many toxic contaminants do not dissolve readily in water, but instead adhere to small sediment particles. Consequently, the bottom sediments in many water bodies are contaminated with metals, PCBs, and other substances. Once toxic, sediments can remain so for years or decades, greatly hampering ecological recovery. Center studies examine patterns of contamination in terrestrial and aquatic environments, identify factors affecting biological uptake and exposure, assess biological effects, develop and test biological indicators of contaminant exposure, and facilitate the identification of remedial measures.