Pfiesteria danger is assessed

Researchers conclude that routine, low-level exposure is not harmful


The algae Pfiesteria, blamed for memory loss among watermen during a 1997 outbreak in a Chesapeake Bay tributary, does not harm people routinely exposed to it at low levels, a study released yesterday concludes.

The research by a team of scientists led by Dr. J. Glenn Morris, chairman of preventive medicine at the University of Maryland School of Medicine, found that the microorganism is common throughout the Chesapeake Bay, from the Patapsco River near Baltimore to the Pocomoke River on the Eastern Shore.

Its widespread presence suggests that the algae might be native to the region, and not an invader that suddenly appeared shortly before the crisis of 1997, when it was linked to ugly lesions on striped bass and fish kills on the Pocomoke River, Morris said. Later research questioned the connection between the fish kills and Pfiesteria.

Rare, extremely high concentrations of Pfiesteria -- or unusual strains of the organism -- might cause the kind of neurological problems experienced nine years ago by fishermen along the Pocomoke River and researchers in a lab studying the algae, Morris said.

But the lower levels found throughout the Chesapeake Bay -- as well as in North Carolina -- cause no health problems to watermen exposed to it on a daily basis, Morris wrote in the July edition of Environmental Health Perspectives.

"The question remains unanswered as to what caused the very real illnesses among persons with exposure to the Pocomoke River in 1997," said Morris, chairman of a state task force appointed nine years ago to investigate the outbreak.

The outbreak of Pfiesteria piscicida, which earned the nickname the "cell from hell," focused national attention on the declining health of the Chesapeake Bay and inspired Maryland's legislature to pass a law requiring farmers to limit their use of fertilizer, which runs into the bay and feeds the growth of algae.

Maryland Watermen's Association President Larry Simns said he was glad to hear that low levels of Pfiesteria don't pose any threat.

"I think most of this stuff about Pfiesteria is a big hoopla," said Simns. "We've dealt with sores on fish for a hundred years."

Morris did not agree that the widely publicized Pfiesteria crisis of 1997 was hysteria.

Back then, about two dozen watermen and researchers working on a section of the Pocomoke where fish had been found with lesions suffered a "very characteristic syndrome that included significant problems with learning and memory," said Morris, who was called in to investigate the illnesses. "It was very distinctive, very striking and very real," Morris said.

Similar memory problems had been reported earlier by researchers exposed to Pfiesteria in the lab of a North Carolina State University researcher.

With funding from the U.S. Centers for Disease Control and Prevention, Morris and eight colleagues examined data from more than 3,500 water samples taken throughout the Chesapeake Bay. They found the algae in more than 30 locations.

The scientists also tested 152 watermen over four years, checking their memory function, verbal fluency and motor skills. The researchers compared the test results from watermen working in rivers with Pfiesteria to the results from fishermen on rivers without the algae. They found no difference between the groups, Morris said.

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