BALTIMORE, MD (March 14, 2002) – The Maryland Department of the Environment (MDE) reopened the lower Potomac River and its Maryland tributaries to shellfish harvesting. The waters had been temporarily closed since February 16 as a precaution due to high concentrations of Dinophysis acuminata, a potentially harmful algae that can produce a toxin harmful to humans.

Toxicity tests conducted by the Food and Drug Administration on algae samples showed the presence of trace amounts of the algae’s toxin, okadaic acid. This toxin can accumulate in oysters and, if ingested, cause diarrhetic shellfish poisoning that can result in gastro-intestinal illness and vomiting. To determine potential health threats, the FDA conducted additional tests of oyster meats sampled from areas with the highest concentrations of algae. The samples showed only trace amounts of toxin from the algae, far below public health standards associated with shellfish borne disease. This new information is allowing MDE to reopen the restricted waters.

The MDE and Virginia authorities kept the waters temporarily closed as a precaution while continued monitoring and testing were conducted and authorities were assured that consumption of shellfish from these waters would not pose a health risk.

The reopened waters are the lower Potomac and its tributaries upstream of a line from Smith Point to Point Lookout which were closed on February 16. Areas previously restricted or conditionally approved in the Potomac River and its tributaries prior to February 16 will remain restricted or conditionally approved.

Both Maryland and Virginia conduct extensive monitoring programs for all shellfish waters to ensure public health is not adversely impacted. It was through this regular monitoring that the algae was originally discovered.

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