A study conducted by the Chesapeake Bay Program (CBP), a federal-state partnership to identify and reduce purported “toxic contaminants” in the Chesapeake Bay, has concluded that polychlorinated biphenyls (PCBs) and mercury are widespread through the bay and its watershed. Results of the study also indicate that water quality is impaired to a “localized extent” by dioxins/furans, petroleum hydrocarbons, some chlorinated insecticides (aldrin, chlordane, dieldrin, DDT/DDE, heptachlor epoxide, mirex), and some metals (aluminum, chromium, iron, lead, manganese, and zinc).

Information about other purportedly harmful agents such as pharmaceuticals, household and personal-care products, polybrominated diphenyl ether flame retardants, some pesticides, and biogenic hormones is apparently insufficient to determine the extent of contamination from these groups. Data indicate, however, that “some contaminants from each of these groups may have the potential to be found in many locations throughout the Bay watershed.”

According to the study, research also suggests that toxic effects of some of these constituents may compromise fish health in the Chesapeake Bay watershed, as evidenced by (i) increased incidence of infectious disease and parasite infestations in several species of fish; (ii) feminization (intersex, plasma vitellogenin) and other signs of endocrine disruption of largemouth and smallmouth bass; (iii) reduced reproductive success and recruitment of yellow perch in tributaries in some highly urbanized drainage basins; and (iv) tumors in bottom-dwelling fish.