Asthma Exacerbated by Exposure to Florida Red-Tide Toxins

Daniel G. Baden, Ph.D.
Center for Marine Science Research, UNC Wilmington
P01ES01059

Some of the most deadly and potent natural toxins known are derived from harmful algal blooms also known as red tides. The microalgae Karenia brevis causes red tides each year throughout the Gulf of Mexico. The organism produces a highly potent toxin called brevetoxin. The toxin can be aerosolized by wind and surf and has been reported to cause irritation of the eyes, nose, and throat and respiratory symptoms in exposed people such as commercial fisherman, lifeguards, and recreational beach goers. NIEHS grantee Dan Baden from the University of North Carolina at Wilmington and colleagues report in the respiratory research journal Chest that exposure to brevetoxins exacerbate asthma symptoms in people with physician-diagnosed asthma.

Brevetoxins are sodium channel blockers and may activate histamine leading to immune responses. Previous research in laboratory animals demonstrated that brevetoxins caused airway constriction, a classic symptom of asthma. The new research was conducted in 97 asthmatics who visited a beach for one hour during periods with and without active algal blooms. They carried personal air monitors that were later used to determine the concentration of toxin they were exposed to. All 97 subjects had more difficulty breathing after exposure to brevetoxin determined by a questionnaire and by a series of airflow tests. During the unexposed beach visit, there were no significant differences.

This study expands the findings of earlier work demonstrating that aerosolized brevetoxins cause asthma symptoms in recreational beach goers. These findings could have major implications for asthmatics living near beaches in the Gulf of Mexico region since red tides occur frequently there. Future research will focus on more in-depth analysis of susceptible populations and the potential for long-term effects of brevetoxin exposure.

Citation: Fleming LE, Kirkpatrick B, Backer LC, Bean JA, Wanner A, Reich A, Zaias J, Cheng YS, Pierce R, Naar J, Abraham WM, Baden DG. Aerosolized red-tide toxins (brevetoxins) and asthma. Chest. 2007 Jan;131(1):187-94.