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Boston Harbor and Massachusetts Bay
MWRA Environmental Quality Department

Massachusetts Bay: Winter Flounder Health

Centrotubular hydropic vacuolation (CHV) is a mild condition associated with exposure to contaminants. Incidence of CHV in fish from the outfall site and Deer Island Flats continues to be lower than in the years before the Massachusetts Bay outfall began to discharge sewage effluent from Greater Boston. Liver disease in winter flounder is an indicator of pollution, because the liver can be damaged as contaminants are metabolized.

Flounder livers are tested for levels of lead, mercury, cadmium, copper, nickel, silver, zinc, chromium, PAHs, PCBs, DDT, and ten other pesticides. In order to test for potential human health effects, mercury, PCBs, DDT, and seven other pesticides are also measured in the edible flounder fillets. For many fish species, consumption advisories because of mercury are a concern. However, mercury levels in winter flounder have been stable at about 50-100 parts per billion, well below the U. S. Food and Drug Administration (FDA) limit of 1,000 parts per billion. Levels of PCBs and DDT are also well below FDA limits. PCBs, DDT, and mercury in fillet of flounder caught in the harbor have fluctuated between years. All these chemicals have measured well below the FDA action limits.


CHV in Bay winter flounder