Widely used antifouling biocide lingers in freshwater ecosystems
6444 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / September 1, 2009
anic and Atmospheric Administration, says that the study will likely prompt U.S. policy makers to consider the potential effects of Irgarol on freshwater systems. “The U.S. is having to take a look at what are the critical levels at which Irgarol may pose a risk,” he says. “I just don’t know that we have the information that policy makers or managers need at this point to make those decisions.” The study provides mounting evidence of the damage that Irgarol can have on freshwater species, which have been found to be more vulnerthe adable to extinction than those in coastal ecosystems, says Stephen Lambert, a freshwater ecologist at the University of East Anglia (U.K.). Freshwater aquatic plants typically have a narrower environmental range and are more highly adapted to their ecological niches than their marine counterparts, says Lambert, who has also studied the toxicity of Irgarol. Substances such as Irgarol pose a threat not only to aquatic plants “but to the stability of the sediments, the habitat of the plankton and fish that shelter in them, and hence the overall biodiversity” of freshwater ecosystems. —AMANDA LEIGH MASCARELLI
10.1021/es902146k
UMWELTBUNDESAMT
reviewed by the EU, and the subA biocide called Irgarol, used stance is still legal in the U.S. worldwide to prevent the buildup Irgarol has been reported at enof algae and other organisms on vironmental concentrations of 2.4 the undersides of boats, accumumicrograms per liter (µg/L) in lates and can be toxic to nontarfreshwater systems. So, Mohr and get aquatic plants in freshwater her team performed experiments ecosystems, a new study in ES&T on six indoor pond systems, addhas found (2009, DOI 10.1021/ es900595u). Researchers are learning that the substance persists in sediments and other organic matter and can have a ripple effect throughout freshwater ecosystems. Irgarol works by inhibiting photosynthesis. One of the main ways that this and other biocides are (Left) A control pond and (right) a pond on day 120, after introduced into the water dition of a 5 µg/L concentration of Irgarol. is by leaching from the ing Irgarol at concentrations from paints used on ship hulls; these 0.04 to 5 µg/L. They then monipaints include a biocide to prevent tored the response of the pond the buildup of algae and the subseorganisms for 150 days. All of the quent attachment of mollusks, a aquatic plants in the study were process known as fouling. (Hull affected by the single application fouling increases drag on the vesof Irgarol at varying concentrasels, thereby increasing fuel and tions. The most sensitive species, maintenance costs.) Irgarol is also Myriophyllum verticillatum, reused as a preservative in building sponded with a 50% reduction in materials and wall paints and as a biomass in the presence of just biocide in power plant cooling 0.21 µg/L Irgarol. Another team of systems. researchers is investigating Irgarol use became widespread whether Irgarol acts as an endoafter various bans in the 1980s limcrine disruptor on the freshwater ited the use of another antifouling snail, Radix balthica. compound, tributyltin (TBT), on Mohr says that research is bevessels shorter than 25 meters. Exing done to find suitable alternatensive reports about the toxicity of tives for biocides like Irgarol and TBT led to a worldwide ban propaints that contain copper comhibiting the use of TBT on ships of pounds, which also became any size in 2008. Irgarol began to widely used after the TBT ban. be detected in relevant concentraOne possible approach is to detions in marine environments in velop paints that won’t leach biothe late 1990s and was eventually cides into the water. And work is banned for small boats in the U.K. being done to develop nanopartiand Denmark. But few studies have cles that could inhibit fouling, but looked at the toxicity of Irgarol in the environmental safety of such freshwater environments, says Silnanoparticles has not yet been via Mohr, a limnologist at the Gerproven. man Federal Environment Agency Ed Wirth, an environmental and the lead author of the new chemist with the National Ocestudy. Irgarol’s safety is now being
2009 American Chemical Society
Published on Web 07/21/2009
