Maryland’s seafood industry and recreational fishing in the Chesapeake Bay depend on consumers’ confidence that fish, oysters, and clams from the Chesapeake Bay and its tributaries are of the highest quality. MDE’s fish and shellfish programs put a strong emphasis on preventing pollutants from entering the waters of the State, monitoring the quality of shellfish harvesting waters, and testing edible fish tissue to certify that fish are safe for human consumption.
Past usage and inappropriate disposal of persistent organic substances have resulted in elevated levels of some hazardous substances in waterbodies near major urban centers. Certain fish in these waters, due to their feeding habits, metabolic activity, age and fat content, may accumulate these substances to levels which may be harmful to people consuming these fish frequently throughout their lifetime. The current advisories are the result of contamination due to past use of chlordane and PCBs, which are now banned.
Per- and Polyfluoroalkyl Substances (PFAS) are a family of thousands of human-made
chemicals that are found in a wide range of products used by consumers and industry since the 1940’s. PFAS have been used in a variety of applications including in stain- and water-resistant fabrics and carpeting, cleaning products, paints, and fire-fighting foams due to their resistance to grease, oil, water and heat. Many PFAS are persistent in the environment and can bioaccumulate. The widespread use of PFAS and their ability to remain intact in the environment means that over time PFAS levels from past and current uses can result in increasing levels of environmental contamination which may bioaccumulate throughout the food chain. Understanding the occurrence of PFAS compounds in various environmental compartments (e.g., air, surface water, groundwater, and land) and the routes of human exposure (e.g., in drinking water or in foods such as seafood) is a growing area of science, as environmental and public health professionals seek to better understand the risks to human health posed by PFAS.
The presence of humans in any watershed increases the potential for an adverse impact on shellfish water quality. Impacts range from large and small sewage treatment facility’s discharges and bypasses from sewage pumping stations, to failing septic systems and increased runoff from development and farm animal operations. Where sewage outfalls already exist, closed safety zones surrounding these outfalls are mandated and necessary to protect human health.
Please direct questions or comments about MDE's Fish and Shellfish Programs at (410) 537-3818.