Scientist Calls for TBT Ban : Boat Paint Chemical Seen as a Threat to Marine Life

A chemical mixed in paints that are widely used to keep barnacles and algae off boat bottoms may be poisoning marine life in harbors and marinas worldwide, a UC San Diego marine chemist warns.

Edward D. Goldberg of the Scripps Institution of Oceanography said the chemical tributyltin (TBT) is the most poisonous substance ever introduced into coastal waters.

Goldberg, who is doing a study for the State of California, called for an immediate and permanent ban of such chemically treated paints on commercial and pleasure boats. “We have enough information now to take action,” he said.

Goldberg said concentrations of TBTs measured in Southern California marinas are far in excess of established safe levels for organisms like 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,” he said.

Goldberg’s recommendations come at a time of increasing scientific and government interest in TBTs, primarily because 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 Navy ran into a storm of protest from the states of California and Virginia last year after it filed a study showing that use of TBT-laced paint on its ships would have no adverse environmental effects. The proposal’s opponents, including environmental officials from the two states as well as numerous scientists nationwide, said there is insufficient data to decide whether the Navy should go ahead.

Subsequently, Congress barred any Navy painting until the U.S. Environmental Protection Agency completed its own review and determined whether the substance is safe to use at any levels. The Navy is cooperating with EPA on the research.

French, British Limits

The controversy follows by several years research by French and British authorities that resulted in severe limitations on the use of TBT in those two countries.

The French government in 1982 banned the paints on pleasure crafts less than 25 meters long after mounting evidence over a five-year period showed that oysters along the coastline near heavy concentrations of recreational boats were increasingly malformed and breeding poorly.

The British government has also prohibited the sale of some TBT-based paints and set a maximum water quality concentration of 20 parts per trillion or lower, a level substantially lower than the 50 parts per trillion proposed as a limit by the U.S. Navy but higher than the 2 parts per trillion recently set by the State of North Carolina.

Goldberg said he is reserving judgment on the Navy’s plans to use TBTs on its 600 or so ships, saying that national security considerations could justify military use if the Navy can keep its releases below levels judged as safe by disinterested scientists.

Measurements that Goldberg has made for the state Water Resources Control Board show TBT levels already as high as 1,000 parts per trillion in the Shelter Island Marina in San Diego, around 200 parts per trillion in Chula Vista marinas and around 200 at Moss Landing near Monterey.

A Stronger Position

Goldberg has taken a stronger position than most other scientists who are studying the effects of TBTs and who believe that additional research is needed before a ban or limitation on use can be justified.

But Goldberg is no knee-jerk conservationist. A member of the Scripps faculty since 1949 and an expert on ocean pollutants, he 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 a number of 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.