EPA's report on dioxin to reaffirm link to cancer

September 13, 1994|By Timothy B. Wheeler | Timothy B. Wheeler,Sun Staff Writer

Four years after acknowledging doubts about the dangers of dioxin, the Environmental Protection Agency is poised to confirm its original finding that the chemical compound is a potent poison, one that may cause cancer and other serious health problems even at the extremely low levels to which people are now exposed.

In a 2,000-page draft report to be released today in Washington, the EPA is expected to conclude, after reviewing both animal and human studies, that dioxin is a probable cause of cancer.

The agency also is expected to link exposure to dioxin and related chemical compounds with a broad array of other maladies, including abnormal development of sex organs, decreased fertility and weakened immunity to disease.

An EPA spokesmen stressed that the report is still a draft, but is being released now to subject it to scrutiny by scientists, industry officials and environmentalists. A final determination of the chemical's hazards will not be made until a 120-day comment period is over.

Likely to renew debate

But the federal review, closely followed by both industry and environmental groups, is likely to renew debate over the government's already stringent health standards on exposures to dioxin from air, water and soil.

Even before today's release, the agency has announced plans to require costly new pollution controls on major industrial sources of dioxin, such as municipal waste incinerators and the pulp and paper industry.

In Maryland, EPA's proposed curbs on dioxin emissions from incinerators could require spending more than $100 million to install new pollution controls on the three municipal waste burners now operating in the Baltimore area, which emit a total of 24 pounds of dioxin and related compounds every year, according to Frank Courtright of the state Department of the Environment.

New requirements

New EPA requirements also have been proposed for the pulp and paper industry, which estimates it already has reduced the amount of dioxin its 104 mills discharge into the nation's rivers to where it is practically nondetectable, at a cost of more than $1 billion. Westvaco's paper mill in Luke in Allegany County estimates it has spent $15 million so far and could be forced to spend another $140 million.

Environmentalists have called for bans on incinerators and for replacement or phase-out of industrial uses of chlorine that can produce dioxins. But industries that rely on chlorinated compounds have opposed any such mandates, citing their widespread use in commerce.

Ever since their discovery in the late 1960s, dioxins have been a focus of controversy. They became notorious during and after the Vietnam War, as an ingredient in the herbicide Agent Orange used to defoliate jungle in much of the war zone. U.S. soldiers linked a variety of health complaints they had to being inadvertently sprayed with the agent.

Actually a family of 210 related chemical compounds, dioxins are an accidental byproduct of municipal waste incineration and the manufacture of some plastics, pesticides and other products. They also are produced when chlorinated compounds are used in bleaching paper. Residential wood burning, forest fires and volcanic eruptions also may be sources, though their contribution is still a matter of debate.

Dioxin was considered dangerous enough in 1982 to prompt a government evacuation of the entire town of Times Beach, Mo., where soil contamination was widespread. But by 1991, when EPA launched its reassessment, top government officials suggested that low-level exposure to the substance may be no more risky than "a week of sunbathing," as an article in the New York Times put it.

Now, after nearly four years of public meetings, scientific review and debate, the EPA report has reaffirmed, citing 1990 and 1991 studies of workers exposed to dioxin, that it is likely to cause cancer in humans.

Other links

Though scientists still differ over whether there is enough evidence to confirm the compound is a "known" carcinogen, a July draft of EPA's report found evidence to link it with lung cancer and soft-tissue sarcoma, among others. The agency estimated that the exposed population's increased risk of getting cancer ranged from 1 in 10,000 to 1 in 1,000.

The report also has raised concerns about a wide range of other reproductive, developmental and immunological problems that may be caused by dioxin and a variety of related compounds, including PCBs. Scientists have found that the substances can mimic the sex hormone estrogen in animals, for instance, disrupting sexual development and reproduction.

The chemicals have different impacts on different animal species, and scientists are still debating whether dioxin has the same hormone-disrupting effect in humans.

But "subtle changes" are seen in human liver enzymes and in male sex hormones at or near dioxin levels that are found in people today, the EPA review has found.

People are exposed to dioxin mainly through their diet, the report concludes, by eating meat, fish and dairy products that contain small amounts of the chemical. The compounds originate primarily as airborne pollution, which falls on land and water, then is ingested by animals. The compounds then concentrate in fatty tissues.

"Some of the effects of dioxin and related compounds have been observed in laboratory animals and humans at or near levels to which people in the general population are exposed," according to a July draft of the report.

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