FOR IMMEDIATE RELEASE
April 19, 2006
CONTACT: Jim Tobin
919-653-2582
New Study Suggests Pfiesteria Not the Danger It Was Once Believed
Report in Environmental Health Perspectives says occupational exposure
to Pfiesteria species is not a risk for illness
[Research Triangle Park, NC] Commercial fishermen do not face significant health
risks from routine occupational exposure to Pfiesteria in estuaries. According
to a study recently accepted for publication by Environmental Health Perspectives,
researchers found no correlation between specific human health effects in “watermen” (commercial
fishermen) and low-level exposure to the dinoflagellate Pfiesteria in areas
of the Chesapeake Bay.
In the summer of 1997, a group of watermen working on the Pocomoke River off
the Chesapeake Bay developed a pattern of deficits in learning and memory after
exposure to areas that had been associated with several fish kills, which some
scientists say were caused by Pfiesteria outbreaks. Research personnel studying
Pfiesteria in the laboratory similarly reported neuropsychological deficits
after exposure.
But less is known about the health risks of chronic, low-level exposure to
Pfiesteria strains, which typically are found in estuaries of the U.S. mid-Atlantic
region
in the summer and fall. The current study is the first systematic, multiyear
effort to correlate human health effects with exposure to waterways where Pfiesteria
has been clearly documented.
The research team followed 88 watermen and 19 controls over a total of four
years (1999-2002). Watermen averaged 10 hours or more per week on Maryland Chesapeake
waters or tributaries. Controls--community members matched to the watermen
by zip code, age, and educational level--had minimal contact with estuarine
waters.
Study subjects were questioned biweekly about any symptoms, the amount of time
they had been exposed to waters, and whether they had been exposed to any chemical
toxicants. They underwent neuropsychological testing at the beginning and end
of each year’s summer fishing season. The two-hour tests were designed
to assess a variety of cognitive functions that Pfiesteria research suggested
could be affected by exposure.
The researchers analyzed more than 3,500 samples collected during the study
period from the water column throughout the region where the watermen worked.
Each year,
Pfiesteria was most prevalent during the late summer and early fall, and then
dipped below detection levels in the winter.
The reseachers found no correlation between the watermen’s work in any
area where Pfiesteria was identified and any specific changes on tests or reported
symptoms. The scientists point out that unique, isolated outbreaks of Pfiesteria
or unusually toxic strains of the organism could plausibly cause human health
effects. Absent these conditions, however, watermen do not appear to face significant
health risks during routine occupational exposure to waters where Pfiesteria
is found.
The lead author of the study was J. Glenn Morris of the Department of Epidemiology
and Preventive Medicine, University of Maryland School of Medicine, Baltimore.
Other authors included Lynn M. Grattan, Leslie A. Wilson, Walter Meyer, Robert
McCarter, Holly A. Bowers, J. Richard Hebel, Diane L. Matuszak, and David W.
Oldach. The article is available free of charge at http://www.EHPonline.org/docs/admin/newest.html.
EHP is published by the National Institute of Environmental Health Sciences
(NIEHS), part of the U.S. Department of Health and Human Services. EHP is
an Open Access
journal. More information is available online at http://www.EHPonline.org/.
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Convergence Marketing handles marketing and public relations for EHP, and is
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