Developments in Brief : Experts Seek Curbs on Tin-Based Boat Paint

Marine scientists warn that even minuscule amounts of a tin-based paint used to keep boat hulls free of barnacles and algae can kill and deform fish and may endanger seafood eaters, and they urged in congressional testimony last week that tough restrictions be imposed on tributyltin, or TBT.

The Environmental Protection Agency has been studying the effects of the paint for 18 months, but testing is continuing and any federal restrictions will not be in place until next year, said Douglas D. Campt, director of the agency’s pesticide programs.

But scientists said a year or more of waiting is “environmentally unacceptable.” Although there is scant information on the potential human health impacts of TBT, similar compounds are known to damage the nervous system, said Judith S. Weis, a Rutgers University zoology professor. “Until we know more about its potential impact on human health, it would be wise to restrict its input into the diet.”

The chemical can kill or deform snails, clams, mussels, oysters and salmon at levels well below other toxic substances. For example, TBT kills blue mussels when it is in water at a ratio of one part per 10 billion, according to a subcommittee report.

TBT, however, is much more effective for boats than traditional copper-based paints. The copper-based paints have a life of about one or two years, while TBT paints can last up to seven years.

The Navy, which wants to use TBT paint, says it can save the government $5 million annually in hull-cleaning costs and $110 million in fuel savings by reducing the drag caused by barnacles and other fouling organisms encrusted on a vessel’s hull. But Congress has for the last two years blocked the Navy from using the TBT paints.