Popular Boat Paint Seen as Threat to Coast Marine Life
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.
Boat paints containing TBT turned up in the 1960s as a potent alternative to older, copper-based anti-fouling paints. Over the past decade, TBT marine paints have grown quickly in popularity, thanks to their extraordinary ability to keep boat hulls clean for years. They are up to 1,000 times more effective than the copper-based paints, according to Goldberg.
The amounts of TBT used annually in marine paints in the United States are estimated by Goldberg at 130 tons. That figure is similar to one quoted by Daniel Maykuth, manager of the Tin Research Institute in Ohio.
The paints come in two forms. At first, TBT was incorporated in what are called “free-association” paints, in which TBT is added directly and diffuses quickly into the water. In newer “copolymer” paints, it is chemically mixed and released at a steady rate through hydrolysis over a longer time. The Navy says it would use the slower-release copolymer paints.
The French raised the first questions about unintended effects from the highly toxic substances after fishermen watched oysters in the Baie d’Arcachon grow increasingly malformed. Beginning in 1977, Pacific oysters in the bay began developing into ball shapes, breeding poorly and, in some cases, dying.
Convinced that TBT paints on pleasure craft in the area were to blame, French authorities in 1982 imposed the first of a series of bans on the paints. The bans, whose results are being assessed, apply to pleasure craft less than 25 meters long.
Then the British began doing their own tests, fearing for their oyster industry. They found levels of several parts per billion--far higher than the parts per trillion levels currently in force--in marinas and estuaries along the coast, particularly where small boats were concentrated. They also introduced TBTs to oysters under controlled conditions in laboratory tests.
“Since then, we’ve shown that the symptoms are attributable definitely to TBT,” Dr. John Portman of the British Ministry of Agriculture, Fisheries and Food said in a telephone interview. “Although we can’t say it couldn’t possibly happen with any other compound, we can say very definitely that TBT does cause the balling.”
Britain, too, introduced a partial ban, prohibiting the sale of free-association TBT paints and setting 20 ppt as the highest level at which the chemical would not affect oysters either in the breeding or larval stage. The effects of the ban are now being studied and additional research is under way on the effects of TBTs on a wide variety of mollusks, including mussels and clams.
Portman said there is no evidence that TBTs can move up the food chain into birds and humans, but he cautioned that little research has been done on the problem. He said that the British have not limited TBT use on commercial or military ships but are examining whether levels of concentration leaching from such large craft exceed current safety maximums.
“None of the scientists that have looked at the evidence we have generated has ever questioned seriously whether TBT caused the effects we observed,” Portman said. “I’d agree with (Goldberg), and we are on record as saying TBT is probably the most toxic substance we have ever tested, that we’ve deliberately put into the environment.”
Chemical and paint manufacturers, worried that the U.S. EPA could decide to ban TBT use on boats, have challenged the validity of the British and French tests, arguing that toxicity has not been measured accurately in a non-laboratory environment. They say that, in the ocean, other factors help degrade the TBTs, quickly rendering them nontoxic.
Arthur Sheldon, director of safety and environmental affairs for M&T; Chemicals, a large New Jersey-based manufacturer of organotins, argued that TBTs degrade in the ocean within as little as four to six days.
He said there is no solid proof that TBTs harmed the oysters in the Baie d’Arcachon, which he described as heavily fouled with numerous pollutants. He said his firm’s tests in France suggested the damage could have come from solvents or copper in the bay.
Sheldon said his firm recommended that France simply ban free-association paints, since they generate more TBTs than do copolymer paints. He said the firm had made a similar proposal to the U.S. EPA.
“I think the lab data clearly shows its effect,” Sheldon acknowledged. “But the point I’m trying to make is that, while the lab data does show it, the lab is a very pristine environment and does not have all the influences that cause the degradation.”
Goldberg takes issue with that argument.
“Yes, to establish conclusively the connection between TBTs and the disappearance of organisms is difficult,” Goldberg said. “The evidence is circumstantial but terribly strong. . . . You really need mass mortalities to define the danger, but in marinas, we have seen mass mortalities (of mussels). TBTs might not affect other marine organisms until it reaches higher levels.”
Goldberg uses mussels as his sentinels in judging whether a harbor or marina has high TBT levels. “I look for them on pilings,” he said. If the mussels are not there, he said, “I can almost predict the amount of TBTs that are going to be in the water.”
Goldberg said that TBTs are known to affect primarily mollusks, which take in large amounts of water and do not flush it out readily, therefore retaining the chemical in their systems for long periods of time.
Prof. Donald Crosby of UC Davis, an expert on environmental toxics, said that the potency of TBTs and similar substances represent “an amber light” of warning but that “at present I don’t think we are in the position to ban tin compounds or anything of the sort. . . . We need to find out where the hazard lies so we can handle them intelligently.”
Crosby said that he “can’t get too excited about just the aspect of mollusks or other creatures in marinas dying out since we are going to have to decide whether that is important to us. . . . Having been around marinas for a good deal, a marina is already dead.”
But Goldberg says that “even if the effects are seen only in marinas, we have a worldwide problem of knocking out organisms in marinas, and I don’t think society has the right to play God, to regulate what organisms will or will not exist in nature.
“But further, we really don’t know all the interactions that occur in estuaries. The disappearance of one organism can affect the vitality of many others.”
The question of how to judge the toxicity of TBTs is now before a special EPA scientific committee. The committee must consider conflicting laboratory data on the levels at which the chemical will affect what kinds of organisms and whether those laboratory levels coincide with levels in actual marina and coastal environments. In addition, the predicted levels of TBTs from Navy use could differ depending on the type of paint used and whether future commercial and recreational painting is prohibited.
Already in the United States, North Carolina has acted to set a TBT safe level--2 ppt in salt water and 8 ppt in fresh water--which is lower even than the British level of 20 ppt.
North Carolina happened upon TBTs almost inadvertently.
In 1983, the state’s environmental agency began a toxics testing program and discovered toxics in the effluent from textile-mill cooling towers. The toxics, emptying into the state’s rivers, were identified as TBTs, used as a biocide in the cooling towers.
State environmental officials then studied the scientific literature on TBTs and did lab tests to determine toxicity levels on organisms like minnows and water fleas. At first, they concluded that emissions into water were unsafe at any level.
“We want to pick a level where we won’t have any chronic effects, a level at which organisms can metabolize and detoxify it,” said John Dorney, an environmental chemist with the state’s Department of Natural Resources and Community Development. “The original proposal was a standard of zero . . . because it’s very toxic and there’s not that much data.”
Dorney’s neighbor to the north, Virginia, began its research after the Navy proposal. The East Coast’s largest naval base, at Norfolk, Va., lies near the economically important spawning areas of crab and oyster in the Chesapeake Bay. Scientists are sampling waters near Norfolk and Hampton Roads, and in several marinas and open bay waters.
Dr. Robert Huggett, chairman of the Department of Chemical Oceanography at the School of Marine Science of the College of William and Mary, said his team found concentrations of up to 200 ppt in marinas and up to 50 ppt in open waters.
Early this year, the team intensified its work and is now testing the effects of TBTs on the larval forms of the Eastern oyster. Several months ago, Huggett’s institute recommended that the state consider restrictions on the use of free-association paints.
“My personal scientific opinion . . . is I think we’ve got problems in our marina areas now,” Huggett said, stressing that he was speaking for himself and not for the school. He said lab data indicate the levels in marinas are “approaching toxic levels.”
Huggett said the link between TBTs and deformed oysters in France and England seems clear.
“It’s pretty conclusive, as far as I’m concerned,” he said. “One can always argue, if you want to. Seldom in science do you have an actual smoking gun. But I think in this case it’s pretty close.”
Nevertheless, Huggett said that there is little evidence yet on whether the problem extends outside of marinas and other areas that have little tidal flushing. He said that he sees no way to set a safety factor yet, citing a lack of data.
The current EPA study resulted in part from a rider attached by Congress to the 1986 appropriations bill barring the Navy from spending any money on TBT paints until EPA could conduct a special review. The passage came at the urging of senators from Virginia and other Eastern states.
Linda Kay Vlier, senior review manager with EPA’s Office of Pesticide Programs, said her office is collecting information on TBTs and monitoring Chesapeake Bay, and intends eventually to decide whether the paints need more regulation.
The options available to the agency range from allowing continued use of the paints to requiring adjustments in their formulation to an outright ban, Vlier said. Dorney said North Carolina officials wrote to EPA supporting a ban on the use of TBT in boat paint.
In the meantime, EPA recently issued a press release to outdoor editors of popular publications encouraging the use of copper-based, instead of tin-based paints, and copolymer, instead of free-association, TBT paints.
“The trigger was that we have data indicating that some of this TBT will kill marine microorganisms,” Al Heier, an EPA spokesman, said of the TBT review. "(The data indicate) it will not only kill them, but it will kill non-target organisms at levels that we find now in waters.”