Human Health Risks of Exposure to Estuary Waters

The convergence of data strongly suggests the presence of an estuary-related toxin (pfiesteria piscicida or similar organism) that produces adverse human health effects. A diversity of methodological approaches is necessary to answer important preliminary questions about the clinical syndrome, its immediate public health risk, prioritize ongoing scientific studies and direct future research. These include intensive case and multiple-case studies; case-control studies; and epidemiological cohort studies that are conducted in parallel with basic science research. Findings to date indicate the estuary-related toxin is neurotoxic to persons with high levels of exposure. The most pronounced effects are neurocognitive and include problems with complex attention, memory, and visual contrast sensitivity. The disturbances are detectable with standard neuropsychological procedures. Although the most debilitating effects are reversible, the possibility of a sensitization phenomenon exists. The Estuary Clinical Syndrome joins other well-documented outbreaks of human illness for which the specific toxin agent remains to be identified. The methodological approaches for identifying and investigating this newly identified syndrome in the absence of a known toxin may provide a model for the early investigation of other emerging toxins and related illnesses.