Red Tide Toxins” Leave Beachgoers Breathless

An ecologic phenomenon known as Florida red tide can impact respiratory function and increase respiratory symptoms in patients with asthma, according to a new study.

Researchers from the Rosenstiel School of Marine and Atmospheric Science at the University of Miami (FL, USA) and other institutions evaluated the exposures and effects of aerosolized Florida red tide toxins in 97 subjects with asthma. The participants spent at least one hour at the Sarasota (FL, USA) Siesta Beach during active Karenia brevis--an ocean organism--bloom (exposure period) and during a period when there was no bloom (nonexposure period). Detailed baseline information was collected, and all participants underwent pre- and post-beach evaluations, including medical history questionnaires, nasal swab sampling, and lung function testing (spirometry). The researchers also collected water and air samples and monitored air temperature, relative humidity, and wind speed and direction.

During exposure periods, participants reported a significant increase in respiratory symptoms, predominantly chest tightness, and differences were measured objectively on lung function testing. In contrast, no significant differences were observed between pre- and post- beach symptoms or spirometry during nonexposure periods. The study appears in the January 2007 issue of Chest.

"In the normal population, inhaled aerosolized red tide toxins can lead to eye irritation, rhinorrhea, nonproductive cough, and wheezing. However, these symptoms usually subside after leaving beach areas,” said lead author Lora E. Fleming, M.D., Ph.D. "Our study shows that Florida red tide toxins may have a greater impact on patients with asthma, who experienced respiratory problems.”

Florida red tide is an algae bloom caused by a species of dinoflagellate known as K brevis that occur almost annually along Florida waters. The density of these organisms during a bloom can exceed tens of millions of cells per liter of seawater, and often discolor the water a deep reddish-brown hue. The most conspicuous effects of red tides are the associated wildlife mortalities among marine and coastal species of fish, birds, marine mammals, and other organisms, caused by exposure to a potent neurotoxin produced naturally by K brevis called brevetoxin.



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