FROM THE WASHINGTON TIMES 9/23/98:
Low-level pfiesteria may affect humans
by Margie Hyslop
The Washington Times
Evidence and theory suggest the organism associated with fish kills in tributaries of the upper Chesapeake Bay may affect people exposed to it at low levels over time, leading researchers said yesterday.
Exposure to Pfiesteria piscicida at low concentrations may cause lesions found on fish outside fish- kill areas, researchers said at a briefing in the District sponsored by the National Sea Grant College Program.
To answer many questions surrounding the mysterious organism, scientists are developing quicker, cheaper ways of detecting it even before it produces toxins. And doctors have begun a five-year study to track its long-term effects on humans.
JoAnn Burkholder, a pioneer in studying pfiesteria at North Carolina State University said she is confident new research will lead to discovering health effects beyond those documented in a University of Maryland Medical School study released last month.
That research showed people with high exposure to Pocomoke River waters around an August 1997 fish kill lost much of the short-term memory and concentration ability needed to perform daily tasks.
While higher exposure correlated to more memory loss, over time all regained cognitive abilities within a range regarded as :normal," although some report they have not recovered all they lost.
Some people exposed to pfiesteria reported vision problems, especially in distinguishing contrasts in shading.
While the organism seemed to produce reddened bumps similar to an allergic reaction, on human skin, it did not produce lesions like those found on fish.
Fish exposed to high concentrations of pfiesteria-produced toxins die quickly, but not all of them have lesions. That suggests that the lesions only make it easier for the toxins to enter the body, researchers said.
What is clear is that nutrients - such as nitrogen and phosphorus that can wash into streams, creeks and rivers from fertilizers applied to fields - stimulate pfiesteria to make toxins, if the conditions are right, they said.
Although warmer water and scant rainfall led to speculation that large fish kills wound occur this year, none did. Late-summer hurricanes probably stirred the water to prevent high concentrations of the organism, Mrs. Burkholder said.
While runoff from pig waster has been shown to cause production of toxins, runoff from chicken waste, often applied as a fertilizer on some Eastern Shore farms and implicated in fish kills there, has not been tested.
But new methods of detecting the organism could cut costs from $1,500 to $15 per test said Parke Rublee, a professor at the University of North Carolina at Greensboro.
The new tests yield results more quickly and may reduce turnaround time next year from three weeks to one to two days, he said. That would make it easier to document the organism’s presence and research its effects next summer.
And although scientists have not found a way to prove fish and shellfish are pfiesteria-free, there is no evidence of people getting sick from eating fish that may have been exposed, said David Green, professor of food science at North Carolina State.
© The Washington Times, 1998