The Current of Red Tide Research. (NIEHS News)

Article excerpt

An interdisciplinary group of scientists from federal and state government, academic, and research institutions have completed the first phase of data collection for human exposure to aerosolized brevetoxins during red tide events. Brevetoxins are potent neurotoxins produced by the dinoflagellate Karenia brevis (previously classified as Gymnodinium breve), a marine microalga found in the Gulf of Mexico and the western North Atlantic. The first portion of this study, known as the 2001 Occupational Red Tide Survey, is being funded by the Florida Department of Health, the Centers for Disease Control and Prevention (CDC), the Florida Harmful Algal Bloom Taskforce, and the NIEHS. The group is being led by Daniel Baden, director of the Center for Marine Science at the University of North Carolina at Wilmington, and Lorrie Backer, leader of the CDC's Emerging Environmental Threats Team.

On an almost annual basis, K. brevis forms large toxic blooms, known as red tides, particularly along the west coast of Florida. An extensive bloom of K. brevis red tide such as the one present in Florida since late in the summer of 2001 can kill tons of fish. Marine mammals (such as the highly endangered West Indian manatee) and birds also succumb to the respiratory paralysis and other neurotoxic effects caused by exposure to brevetoxins.

One recognized human health effect from exposure to K. brevis and its toxins is neurotoxic shellfish poisoning (NSP), which can occur when people eat shellfish that have been contaminated through filter-feeding activities. NSP can be prevented by monitoring waters for K. brevis and rapidly closing shellfish beds when blooms approach; in the United States, the only reported cases of NSP in about 30 years have been from the consumption of shellfish collected illegally from closed beds.

In addition to NSP, people have reported a number of symptoms, including respiratory complaints, after being on or near the beach during a red tide event. Although a link has not been scientifically and medically demonstrated, scientists believe these symptoms are caused by exposure to aerosolized brevetoxins and perhaps airborne K. brevis cellular debris generated during red tide events. …