LA JOLLA — A chemical mixed in paints widely used to keep barnacles and algae off boat bottoms may also be poisoning marine life in harbors and marinas worldwide as it leaches into coastal waters, a well-known UC San Diego marine chemist warns.
Edward D. Goldberg of the Scripps Institution of Oceanography, based on studies he is doing for the State of California, calls for an immediate and permanent ban of such chemically treated paints on commercial and pleasure boats.
"We have enough information now to take action," said Goldberg, describing the chemical tributyltin (TBT) as the most poisonous substance ever introduced into coastal waters. Goldberg argues that the federal government should follow the precedent set when it banned DDT in the early 1970s as a means of protecting animal ecosystems, despite the lack of evidence that the chemical could harm humans.
"I think this is a situation where we have to act based on what we have seen," Goldberg said, noting concentrations of TBTs measured in Southern California marinas far exceeding established safe levels for organisms such as mussels and oysters. "If the use is continued, if there is more extensive use as barnacles become resistant to (present levels), then the impact will be more widespread in more organisms.
"Based on past experience and present knowledge, I don't think we can gamble. One has to blend a little intuition into objectivity, which is what was done with DDT, even though there are no observable effects on higher organisms at the present time."
Goldberg's recommendations come at a time of increasing scientific and government interest in TBTs, primarily as a result of a U.S. Navy proposal to paint its entire fleet with the anti-fouling paint to save hundreds of millions of dollars annually in fuel and maintenance costs. The paint is so effective because, instead of just resisting organisms' efforts to attach themselves to the hull, it actually kills them.
The Navy ran into a storm of protest from California and Virginia last year after it filed a study showing that use of TBT-laced paint on its ships would have no adverse effect on the marine environment. Environmental officials from the two states, along with numerous scientists nationwide, said there is insufficient data to decide whether the Navy should go ahead. Subsequently, Congress last year forbade any Navy painting until the federal Environmental Protection Agency completes its own review and determines whether the substance is safe to use--at any level. The Navy is cooperating with EPA on the research.
The American interest follows by several years research by French and British authorities that resulted in severe limits on the use of TBT in those two countries.
The French government in 1982 banned the paints on pleasure craft less than 25 meters long after mounting evidence over a five-year period that oysters along the coastline near heavy concentrations of recreational boats were increasingly malformed and breeding poorly.
The British government has also introduced a partial ban based on its own problems with oysters, prohibiting the sale of some TBT-based paints and setting a maximum water quality concentration of 20 parts per trillion (ppt) or lower, a level substantially lower than the 50 ppt proposed as a limit by the U.S. Navy but higher than the 2 ppt recently set by North Carolina.
Goldberg reserves judgment on the Navy's plans to use TBTs on its 600 or so ships, saying that potential benefits to national security could justify military use if the Navy can keep its releases below levels judged as safe by disinterested scientists.
But he sees no reason not to ban the paints now for pleasure and commercial craft, which number in the tens of thousands and apparently have far more impact on coastal waters than would Navy craft.
Measurements that Goldberg has made for the state Water Resources Control Board show TBT levels already as high as 1,000 ppt in the Shelter Island Marina in San Diego, about 200 ppt in Chula Vista marinas and about 200 ppt at Moss Landing near Monterey.
Goldberg has taken a stronger position than most other scientists who are studying the effects of TBTs. Most believe that additional research is needed before a ban or limit on use can be justified. But Goldberg is no knee-jerk conservationist. The prominent chemist, a member of the Scripps faculty since 1949 and an expert on ocean pollutants, has earned the ire of environmental groups in the past by positing data to show that oceans can safely assimilate far more human waste and garbage than amounts now being dumped.
TBT is one of several compounds known as organotins, first recognized in the 1950s by Dutch scientists as having the useful capacity to kill organisms. Since then, organotins have been used widely as fungicides, bactericides and preservatives in wood, textiles and paper.