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Aerosolized Red-Tide Toxins (Brevetoxins) and Asthma^*

^* From the National Institute of Environmental Health Sciences Marine and Freshwater Biomedical Sciences Center (Drs. Fleming, Zaias, and Abraham), Rosenstiel School of Marine and Atmospheric Sciences, and School of Medicine (Dr. Wanner), University of Miami, Miami, FL; Mote Marine Laboratory (Drs. Kirkpatrick and Pierce), Sarasota, FL; National Center for Environmental Health (Dr. Backer), Centers for Disease Control and Prevention, Atlanta, GA; Children’s Hospital Medical Center and University of Cincinnati (Dr. Bean), Cincinnati, OH; Florida Department of Health (Mr. Reich), Tallahassee, FL; Lovelace Respiratory Research Institute (Dr. Cheng), Albuquerque, NM; and the Center for Marine Science Research (Drs. Naar and Baden), University of North Carolina at Wilmington, Wilmington, NC.

Correspondence to: Lora E. Fleming, MD, PhD, MPH, MSc, c/o Department of Epidemiology & Public Health, University of Miami School of Medicine, 1801 NW Ninth Ave, Highland Professional Building, Suite 200 (R 669), Miami, FL 33136; e-mail: lfleming{at}med.miami.edu

Abstract

Background: With the increasing incidence of asthma, there is increasing concern over environmental exposures that may trigger asthma exacerbations. Blooms of the marine microalgae, Karenia brevis, cause red tides (or harmful algal blooms) annually throughout the Gulf of Mexico. K brevis produces highly potent natural polyether toxins, called brevetoxins, which are sodium channel blockers, and possibly histamine activators. In experimental animals, brevetoxins cause significant bronchoconstriction. In humans, a significant increase in self-reported respiratory symptoms has been described after recreational and occupational exposures to Florida red-tide aerosols, particularly among individuals with asthma.

Methods: Before and after 1 h spent on beaches with and without an active K brevis red-tide exposure, 97 persons 12 years of age with physician-diagnosed asthma were evaluated by questionnaire and spirometry. Concomitant environmental monitoring, water and air sampling, and personal monitoring for brevetoxins were performed.

Results: Participants were significantly more likely to report respiratory symptoms after K brevis red-tide aerosol exposure than before exposure. Participants demonstrated small, but statistically significant, decreases in FEV₁, midexpiratory phase of forced expiratory flow, and peak expiratory flow after exposure, particularly among those participants regularly using asthma medications. No significant differences were detected when there was no Florida red tide (ie, during nonexposure periods).

Conclusions: This study demonstrated objectively measurable adverse changes in lung function from exposure to aerosolized Florida red-tide toxins in asthmatic subjects, particularly among those requiring regular therapy with asthma medications. Future studies will assess these susceptible subpopulations in more depth, as well as the possible long-term effects of these toxins.

Key Words: asthma • brevetoxins • harmful algal blooms • Karenia brevis • red tides • sensitive populations • spirometry