Widely used antifouling biocide lingers in freshwater ecosystems

Widely used antifouling biocide lingers in freshwater ecosystems

via ES&T Online News on 7/22/09

A growing body of evidence shows that Irgarol and other biocides present a toxic threat to vulnerable freshwater organisms.

Excerpt:

A biocide called Irgarol, used worldwide to prevent the buildup of algae and other organisms on the undersides of boats, accumulates and can be toxic to nontarget aquatic plants in freshwater ecosystems, a new study in ES&T has 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 introduced into the water is by leaching from the paints used on ship hulls; these paints include a biocide to prevent the buildup of algae and the subsequent attachment of mollusks, a process known as fouling. (Hull fouling increases drag on the vessels, thereby increasing fuel and maintenance costs.) Irgarol is also used as a preservative in building materials and wall paints and as a biocide in power plant cooling systems.

My thoughts:

1. Nothing new here - another chemical dispersing into the environment and causing undesired effects on the ecosystem.
2. Question - are toxicity studies actually done for this chemical before its introduction to the market? If yes, how extensive are they in terms of the run time and variety of organisms tested?
3. Question - why does it take so long for its adverse effects to be investigated? According to the article, Irgarol started to be widely used in the 1980s but this study only comes out now.
4. According to the author, Irgarol is more damaging to freshwater aquatic plants compared to coastal aquatic plants because freshwater plants have a smaller range of tolerance to changes in the environment. I am not sure I agree with this. Marine organisms such as seagrasses, coral and plankton are pretty sensitive too. More research should be done as there are many more ocean going vessels using anti-fouling agents.

on the vessels, thereby increasing fuel and maintenance costs.) Irgarol is also used as a preservative in building materials and wall paints and as a biocide in power plant cooling systems.