Aerosol toxins from red tides may cause long-term health threat

NOAA scientists reported in the current issue of the journalEnvironmental Health Perspectives that an algal toxin commonlyinhaled in sea spray, attacks and damages DNA in the lungs oflaboratory rats. The findings document how the body's way ofdisposing the toxin inadvertently converts it to a molecule thatdamages DNA. Human inhalation of brevetoxins produced by the red tideorganism, Karenia brevis, is an increasing public health concern.

The scientists, led by John Ramsdell of NOAA's Center forEnvironmental Health and Biomolecular Research in Charleston, S.C.,determined that brevetoxins react with DNA of lung tissue and attachto the DNA-bases that code genetic information. The linkage ofchemicals in the environment to DNA is a first step for many cancercausing agents and can lead to mutations in genes that normallyprevent the formation of cancers.

The red tide toxin, brevetoxin, has long been recognized as a causeof both neurotoxic poisoning after both consumption of toxicshellfish as well as a respiratory irritation after inhalation oftoxic sea spray. Groundbreaking research, leading to this thirdpotential form of poisoning, identified that metabolism produceschemically reactive forms of the toxin. Recognizing the potential ofthese metabolites to attack DNA, NOAA scientists analyzed the DNAafter the toxin was metabolized in the lung. Scientists have not yetdetermined if brevetoxin damaged DNA accurately repairs itself or ifgene mutations result.Brevetoxin has been measured in air during red tide events and humanexposure levels have been reported; however, the long-term healthrisk associated with inhalation of brevetoxins remains to be defined.Individuals are continually exposed to environmental chemicalscapable of damaging DNA like carcinogens found in tobacco smoke andair pollution. It is possible that exposure to brevetoxins can add tothe cumulative amount of chemically altered DNA in the lungs; anindicator of cancer risk.

"This represents a significant breakthrough in defining the metabolictransformation of brevetoxins and the potential long-term healtheffects of red tides. It should change perceptions of risk andmanagement of inhalation exposure to harmful algal blooms," notes Ramsdell.

Red tides in the Gulf of Mexico are common, and often persistent,naturally occurring events that release toxins into sea sprayaerosols. These aerosols are a particular problem at beaches, as theycan cause respiratory distress to lifeguards and beachgoers. Althoughthese shorter-term effects of the airborne toxin are wellcharacterized, potential longer-term effects remain a concern tohealth officials and coastal communities.

cientists, in NOAA's Oceans and Human Health Initiative, arestudying long term health consequences of harmful algal blooms, topredict how the condition of the coastal waters affect human healthand how to reduce or eliminate health risks.

Source: NOAA Headquarters