A wave of momentum for toxic algae study.

As blooms of blue-green algae proliferate in U.S. lakes and rivers, deadly liver and nerve toxins produced by these cyanobacteria loom large on the radar of officials charged with ensuring safe drinking water. Water utility managers commonly treat affected waters to correct taste and odor problems associated with the algae, but scientists are worried about traces of toxins that slip through water treatment processes and their long-term health effects in humans, especially given an increased reliance on surface waters to meet drinking water demands. In Florida, for instance, water treatment officials anticipate that groundwater demands will exceed supply by the year 2020; currently 10–15% of Florida’s drinking water is supplied by surface waters. At a two-hour forum held 12 January 2001 at the NIEHS campus in Research Triangle Park, North Carolina, key players in the study of and fight against cyanobacteria species including Microcystis, Cylindrospermopsis, and Anabaena had the chance to meet and plant the seeds for possible future collaborations in new cyanobacteria research. Arranged by NIEHS staff scientist Gary Boorman, the informal meeting was attended by about 70 people, including public utility managers, water quality officials, and representatives from the U.S. Environmental Protection Agency (EPA) and the U.S. Geological Survey. The meeting came on the heels of a recommendation for federally sponsored toxicity studies of the most commonly found cyanotoxin, microcystin-LR. The Interagency Committee for Chemical Evaluation and Coordination (ICCEC)— an external review body of the National Toxicology Program (NTP) composed of representatives from the major federal agencies involved in health research—had recommended in October 2000 that microcystin be evaluated by the NTP for chronic toxicity and carcinogenicity in humans. Following a public comment period and subsequent review by appropriate committees, a decision could be made as early as spring 2001 as to whether the chemicals should be studied by the NTP. Boorman says the ICCEC will consider the need to evaluate the toxin cylindrospermopsin this spring. Florida’s situation illustrates the need for more and better information on the human health effects of cyanobacteria. Florida surface waters are significantly contaminated by toxin-producing cyanobacteria. Of 167 samples taken from Florida waters in a 1999 study, 88 samples representing 75 individual bodies of water contained significant levels of toxic cyanobacterial species, says John Burns, Jr., an environmental scientist for the St. Johns River Water Management District in Palatka, Florida. Seventy-eight percent of samples with measurable levels of microcystins and cylindrospermopsin were lethal when injected into mice, and 80% of the microcystin-laden samples showed potential tumor-producing properties. High levels of cylindrospermopsin also were measured in finished drinking water samples, says Burns. “This suggests that this particular toxin does pass through the drinking water treatment process, at least in some of these plants,” he says. Spikes in microcystins have also been found in the state’s treated drinking water samples. “I know we have at least one sample that was 10 times the provisional World Health Organization guideline for microcystins [of 1.0 microgram per liter],” he says. Many factors may account for toxins passing through treatment processes, says Burns— the choice of filtering agent, for instance, or the concentration of toxin entering a plant. In addition, Burns says, “A water treatment plant may remove toxins with activated carbon when treating for taste and odor, but if they don’t monitor for toxin type and concentration entering the plant, the methods used may not remove or reduce these compounds to safe levels.” Cyanobacteria and their associated toxins are listed on the EPA’s Drinking Water Candidate Contaminant List, which includes contaminants being considered for