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Marian Swinker,¹ Deborah Koltai,² Jean Wilkins,³ Ken Hudnell,⁴ Colin Hall,³ Dennis Darcey,² Kevin Robertson,³ Donald Schmechel, ² Woodhall Stopford,² and Stan Music^5,*

¹School of Medicine, East Carolina University, Greenville, North Carolina, USA
²School of Medicine, Duke University, Durham, North Carolina, USA
³School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
⁴United States Environmental Protection Agency, Research Triangle Park, North Carolina, USA
⁵North Carolina Department of Health and Human Services, Raleigh, North Carolina, USA

Abstract

Atlantic coast estuaries recently have experienced fish kills and fish with lesions attributed to Pfiesteria piscicida and related dinoflagellates. Human health effects have been reported from laboratory exposure and from a 1997 Maryland fish kill. North Carolina has recorded Pfiesteria-related fish kill events over the past decade, but human health effects from environmental exposure have not been systematically investigated or documented here. At the request of the state health agency, comprehensive examinations were conducted in a cross-sectional prevalence study of watermen working where Pfiesteria exposure may occur: waters where diseased or stressed fish were reported from June to September 1997, and where Pfiesteria had been identified in the past. Controls worked on unaffected waterways. The study was conducted 3 months after the last documented Pfiesteria-related fish kill. The goal was to document any persistent health effects from recent or remote contact with fish kills, fish with lesions, or affected waterways, using the 1997 U.S. Centers for Disease Control and Prevention case description for estuary-associated syndrome (EAS) . Examinations included comprehensive medical, occupational, and environmental history, general medical, dermatologic, and neurologic examinations, vision testing, and neuropsychologic evaluations. Seventeen of 22 watermen working in affected waters and 11 of 21 in unaffected waters reported exposure to a fish kill or to fish with lesions. We found no pattern of abnormalities on medical, neurologic, neuropsychologic, or NES-2 evaluation. By history, one subject in each group met the EAS criteria, neither of whom had significant neuropsychological impairment when examined. Watermen from affected waterways had a significant reduction in visual contrast sensitivity (VCS) at the midspatial frequencies, but we did not identify a specific factor or exposure associated with this reduction. The cohorts did not differ in reported occupational exposure to solvents (qualitative) or to other neurotoxicants ; however, exposure history was not sufficiently detailed to measure or control for solvent exposure. This small prevalence study in watermen, conducted 3 months after the last documented fish kill related to Pfiesteria, did not identify an increased risk of estuary-associated syndrome in those working on affected waterways. A significant difference between the estuary and ocean watermen was found on VCS, which could not be attributed to any specific factor or exposure. VCS may be affected by chemicals, drugs, alcohol, and several developmental and degenerative conditions ; it has not been validated as being affected by known exposure to dinoflagellate secretions. VCS should be considered for inclusion in further studies, together with documentation or quantification of its potential confounders, to assess whether it has utility in relationship to dinoflagellate exposure. Key words: dinoflagellate, marine toxin, memory disorders, occupational disease, Pfiesteria, visual contrast sensitivity (VCS) . Environ Health Perspect 109:21-26 (2001) . [Online 30 November 2000]

http://ehpnet1.niehs.nih.gov/docs/2001/109p21-26swinker/ abstract.html

Address correspondence to M. Swinker, Office of Prospective Health, 188 Warren Building, East Carolina University School of Medicine, Greenville, NC 27858 USA. Telephone: (252) 816-2070. Fax: (252) 816-2417. E-mail: swinkerm@mail.ecu.edu

^*Currently with Merck and Company, Inc., West Point, Pennsylvania, USA.

We acknowledge the assistance of our colleagues D. Weber, D. Otto, C. Phillips, D. Rubinstein, and K. Kapoor in conducting the evaluations. We thank K. Buckheit, C.G. Smith, T. Morris, D. Savitz, and W. Burke for reviewing this manuscript.

This work was conducted with financial support from the North Carolina Department of Health and Human Services.

This manuscript was reviewed by the National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the agency, nor does mention of trade names or commercial products constitute endorsement or recommendation.

Received 10 May 2000 ; accepted 22 August 2000.