TOXIC algal blooms may cause lingering damage to your health, even if you鈥檝e
had no symptoms of acute poisoning, the AAAS was told last week.
In the past twenty years, red tides and other algal blooms have become more
frequent across the globe. When blooms occur, shellfish can be lethal to eat
because they concentrate algal toxins. Though careful monitoring means that few
humans are poisoned in developed countries, thousands of cases are reported each
year elsewhere in the world.
Many of the toxins that cause shellfish poisoning are fat-soluble and
accumulate in body tissues just as DDT and PCBs do. That suggests they could
cause lingering damage even in people who don鈥檛 become obviously sick after
eating contaminated seafood. 鈥淭he effects should be chronic and sublethal for
these toxins as they have been found to be for PCBs and other chemicals,鈥� says
JoAnn Burkholder, an algal specialist at North Carolina State University in
Raleigh.
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Anecdotal evidence supports this view. Burkholder herself has suffered
long-term respiratory and immune difficulties after being exposed to low levels
of the toxin produced by the fish-killing alga Pfiesteria piscicida.
鈥淚鈥檓 on antibiotics 120 days a year, and I鈥檝e had 13 cases of pneumonia in the
last five years,鈥� she says. But no one has looked to see whether long-term
exposure to low levels of algal toxins leads to health problems, she says.
Such data may be difficult to gather. The problem is that many of the algal
toxins are poorly understood, and researchers have not yet developed easy and
cheap techniques to detect them in people. 鈥淎s an epidemiologist, it鈥檚 very hard
to work with these things if I can鈥檛 diagnose them,鈥� says Lora Fleming of the
University of Miami.