The role of chlorine - and its future.

Zoologist Theo Colborn of the World Wildlife Fund and her co-workers have compiled a list of 42 chemicals or classes of chemicals that have been reported to affect the reproductive or hormone system. Twenty-three of the compounds -- 55percent - contain chlorine as an essential ingredient. Two others rely on a different halogen, or element in chlorine's chemical class: one on fluorine, the other on bromine.

Because many halogenated compounds are lipophilic (dissolve in fat) and resist breakdown, they tend to persist in the environment -- often decades after their use has been banned -- and to accumulate in body fat.

As a result, animals exposed to these ubiquitous contaminants frequently become walking, flying, or swimming reservoirs of toxic pollution. Indeed, at least 50 of the papers presented last October at the Ecological Effects of Arctic Airborne Contaminants meeting in Reykjavik, Iceland, dealt with the accumulation of such organochlorines in water and soil and throughout the food chain- from lichens, mosses, fish, and waterfowl to caribou, whales, and newborn harp seals.

Referring to such chlorinated chemicals, Tom Muir, a senior economist with Environment Canada in Burlington, Ontario, argues that "no other class of industrial -- or natural -- chemicals is known that exhibits so many detrimental properties at the same time. Put simply, the characteristics of chlorihated organic substances that give them useful technical properties are the same ones that make them persistent and/or toxic."

In a 67-page report- Chlorine, Human Health, and the Environment-- released last October, Greenpeace USA argued that "no further organochlorine pollution should be permitted." Said Joe Thornton, the author, this "means phasing out the substance that is their root -- chlorine, since whenever chlorine is used, organochlorines result,"

Several other groups have issued similar, less-publicized recommendations. At its annual meeting in October 1992, the International Joint Commission (IJC) suggested that its patrons "sunset" - or begin commercially phasing out - persistent toxic chemicals. A federally appointed U.S.-Canadian board, IJC was established in 1909 to advise the U.S. and Canadian governments on how best to implement treaties and laws for preserving water quality in areas along their joint border. Though nonbinding, the commission's recommendations are taken seriously by both governments, notes Marty Bratzel in IJC's Windsor, Ontario, office.

While IJC has addressed a broad spectrum of persistent toxic agents, its recommendation specifically urges that the U.S. and Canadian governments "develop timetables to sunset the use of chlorine and chlorine-containing compounds as industrial feedstocks, and that the means of reducing or eliminating other uses be examined."

At a September 1992 meeting of the Paris Commission for the Prevention of Marine Pollution, ministers of 15 European nations also agreed that releases of halogenated organics and persistent toxic chemicals should be cut- "with the aim of their elimination."

And last Oct. 27, at its annual meeting, the American Public Health Association% governing council passed a resolution on these organics. It concluded that "there should be a rebuttable presumption that chlorine-containing organic chemicals pose a siguificant risk. Therefore, before introducing new chemicals into commerce, using existing chemicals in new applications, or continuing to use these chemicals in the manufacturing processes or products beyond some future date, industry should either:

* demonstrate that the risk is not significant for a particular compound, use, or manufacturing process, or

* demonstrate that there are no substitutions, product reformulations, or changes in manufacturing processes that will result in a lower risk, or

* ensure that substitutes for existing products or changes in manufacturing processes will result in a lower risk."

Not surprisingly, the chemical industry has responded. Publicly it argues that such sweeping recommendations are not justified or go too far. Internally, however, many companies have begun evaluating what they can do to begin cutting their chlorine use and pollution.

Last October, in fact, Philip H. Brodsky, director of corporate research and environmental technology at Monsanto Co. in St. Louis, made new efforts to develop chlorine-cleanup and chlorine-substitution technologies the focus of his presentation before journalists at the Council for the Advancement of Science Writing.

And what of the scientists whose work Greenpeace cited to support a chlorine ban? Says Mary S. Wolff of the Mt. Sinai School of Medicine in New York City, whose team last year linked concentrations of DDT in the blood to a woman's risk of breast cancer (SN: 4/24/93, p.262): "I don't think any scientist would be against a ban on chlorinated organics." But does she support a ban on all chlorinated compounds? "No?

Calling for a chlorine ban "is an extremist position, and like most extremist positions, ridiculous," charges endocrinologist H. Leon Bradlow of Cornell University's Strang Cancer Prevention Center in New York City. He acknowledges that all toxic chemicals should be used judiciously and only when suitable nontoxic substitutes aren't available. However, he quips: "l think methylene chloride [an animal carcinogen] is a dandy solvent and would hate not to be able to use it."

Reproductive biologist Ana Solo of Tufts University Medical School also considers a chlorine ban an overly simplistic approach to regulation. Moreover, she notes, such a ban would not affect unchlorinated compounds such as nonylphenol - a substance whose estrogenicity she discovered when it leached out of plastics, destroying four months of endocrine research.

Soto also notes that, unlike chlorinated pesticicles, some nonylphenolcontaining products - such as spermicides used with contraceptive diaphragms and in many condoms - have been designed expressly for intimate contact with human reproductive tissue.

Adds toxicologist Devra Lee Davis with the Department of Health and Human Services in Washington, D.C., "We're not well served by blanket solutions to complicated problems." However, she asserts, "I'm glad I live in a democratic country where discussions like those that Greenpeace has been leading on this chlorine issue, can be aired before the public."