Pfiesteria prognosis remains uncertain Study unable to produce firm conclusions

March 21, 1998|By Heather Dewar | Heather Dewar,SUN STAFF

Researchers still can't say whether Pfiesteria piscicida causes lingering health problems in people, despite a new North Carolina study that failed to find no long-term health effects, scientists in that state and Maryland said yesterday.

The North Carolina study looked at about 50 people and found that none had health problems clearly linked to Pfiesteria. The study found no significant health differences between people who might have been exposed and those who probably weren't.

Critics said the study -- the state's first on health effects of the toxic microorganism that has infested North Carolina rivers since the early 1990s -- was flawed, and a top North Carolina health official said its main benefit was to teach researchers how to do better in future studies.

Studying the health effects of Pfiesteria is "extraordinarily difficult and complicated," said Dr. Stan Music of the North Carolina Department of Health and Human Services. The new study "taught us a great deal about what we need to do to do it right," he said.

"You still have to have a question mark about whether we selected the right people or not," Music said. Some of the study's fishermen, who were assumed to have been exposed to Pfiesteria, might not have been, Music said. And some of the people considered unexposed might have swum or fished in Pfiesteria-tainted waters.

For years, North Carolina fishermen and state employees working on the water complained of skin lesions, memory problems, shortness of breath and other health woes that they blamed on Pfiesteria. The state began a medical study last fall, shortly after Maryland researchers found signs of illness in 13 people who said they had been on the scene of toxic Pfiesteria outbreaks on the Lower Eastern Shore.

In Maryland, researchers found some watermen and state employees working on the water had memory gaps and struggled with simple mental tasks such as remembering a short sequence of numbers. Three months later, the Maryland scientists retested 12 of the 13 and found all had returned to normal.

Scientists think the effects of Pfiesteria are short-lived in all but the worst cases. Some Marylanders and North Carolinians say they remain sick months or years after being exposed to Pfiesteria.

That might be true, scientists say, but the extent of any lingering illness is impossible to measure because researchers lack data that would tell them whether the people studied had health problems before being exposed to Pfiesteria.

The North Carolina study began about two years after that state's most recent Pfiesteria outbreak. As a result, researchers there were limited to measuring relatively long-term effects, which are the most difficult to track.

"They had a lot of obstacles and a lot of barriers," said Dr. Trish Perl of the Johns Hopkins University, a member of the Maryland research team. "They got started late. I think they were asking too much."

Music, chief of occupational and environmental epidemiology for the North Carolina health agency, said researchers met yesterday to plan a more comprehensive study that could give a clearer picture of Pfiesteria's health effects. Maryland researchers are also beginning new studies, Perl said.

Pub Date: 3/21/98

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