* US Congress on a mission to save dioxin &amp&amp

Wednesday, September 13, 1995

Peter Montague

People calling themselves "conservatives" in Congress are preparing to flay US Environmental Protection Agency (EPA) scientists for the agency's four-year effort to determine the true hazards of dioxin. Dioxin is a highly toxic by-product produced in the manufacture of many pesticides, and by the routine operation of all incinerators, metal smelters and chlorine-using paper mills. In 1986, EPA concluded that dioxin was one of the two or three most powerful poisons ever studied and, accordingly, set strict limits on certain releases into water.

As the agency moved to enforce those limits in the late 1980s, industrial dioxin-producers developed a strategy for reversing EPA's stance: they would force the agency to undertake a scientific reassessment, one they evidently thought they could control.

The paper industry took the lead in pressuring EPA to formally reassess dioxin. On January 23, 1991, four chief executive officers of paper companies visited William Reilly, who was then the head of EPA. The four executives told Reilly there is now a "prevailing view that low-level dioxin exposures do not pose a serious health threat".

As a direct result, EPA's "scientific reassessment" of dioxin was born. By April 1991, Reilly had geared up his agency for a major effort to reassess the toxicity of dioxin, just as the paper industry had requested. In August, just four months into the multi-year study, Reilly told the New York Times how he expected the dioxin reassessment to turn out: "I don't want to prejudge the issue, but we are seeing new information on dioxin that suggests a lower risk assessment for dioxin should be applied".

However, the reassessment did not turn out as Reilly and the paper industry supposed it would. EPA scientists designed a reassessment process that involved original laboratory research, many meetings with non-government scientists, at least two public hearings and many drafts of the nine-volume reassessment document, which was peer-reviewed prior to release.

Eight of the nine volumes were written by non-governmental scientists. EPA had never before involved such a large number of non-agency scientists in its work.

EPA scientists concluded a year ago that dioxin probably causes cancer in wildlife and humans, and that it harms the immune system and the reproductive systems in fish, birds and mammals (including humans) at doses that are minuscule.

The lead scientist on the EPA reassessment team, Dr Linda Birnbaum, said she and her colleagues now consider dioxin an "environmental hormone" capable of disrupting a large number of bodily processes in fish, birds and mammals, including humans. Dioxin, EPA said, is especially powerful in its effects on the unborn and the newly born.

The final draft of the reassessment document went to EPA's science advisory board (SAB) this year; at an SAB meeting on May 16, 1995, parts of the dioxin reassessment were criticised. Specifically, the SAB asked EPA to provide better support for some of the conclusions in Volume 9, but it did not tell EPA to do any additional scientific work.

Using the SAB's comments on the reassessment (which have not yet been made public) as a political springboard, a group of so-called "conservatives" of both parties in Congress are planning to investigate "whether sound science is being distorted for preconceived policy ends, and the potential economic impact of future mandates based on this reassessment".

Congress has scheduled a public hearing on September 13 before the House Subcommittee on Energy and the Environment of the Committee on Science. It is widely understood in Washington that this hearing is going to be a "witch-hunt" aimed at punishing EPA for reaching conclusions that the paper industry and other industrial poisoners don't like.

Everyone knows there are a handful of scientists who still claim there is no compelling evidence that tobacco causes lung cancer in humans. These "tobacco scientists" have counterparts in the dioxin world, and this little group of dioxin denial specialists will be showcased at the hearing on September 13. They are expected to say that EPA and its 100 or so independent outside scientific advisers have made a mountain out of a molehill. Congress may use their testimony as an excuse to further slash EPA's research budget.

Meanwhile, the scientific evidence linking dioxin to serious reproductive disorders in mammals has continued to accumulate. Just last month, Dr Earl Gray (a respected EPA researcher) published the third in a series of studies of the effects of a single low dose of dioxin on rats and hamsters. This series began with three studies published in 1992 by Dr. Richard E. Peterson at the University of Wisconsin.

In the Peterson studies, young male rats whose mothers were given as little as 0.064 micrograms of dioxin per kilogram of body weight showed consistently reduced levels of male hormones, plus a variety of sex-related changes, including: smaller accessory sex organs, including smaller testicles; slower sexual maturation; distinctly feminine-style regulation of one hormone related to testosterone production.

The Wisconsin studies indicated that the developing male reproductive system is more sensitive to the effects of dioxin than any other organ or organ-system studied. The unborn or newborn is about 100 times more sensitive to dioxin than the sexually mature animal.

In March 1995, Linda Birnbaum of EPA (with Earl Gray, William Kelce and others) published studies confirming that many of Peterson's findings could be reproduced in another strain of rat, and in another species entirely, the Syrian hamster. The hamster is known for being insensitive to dioxin's effects, yet single low-dose exposures of pregnant hamsters to dioxin produced nearly a 60% reduction in sperm count in male offspring, plus other important changes, such as a 23% reduction in the size of the adrenal gland.

In August, Earl Gray published a third study showing that a single low dose of dioxin to pregnant rats could produce hermaphroditic female offspring. Other effects included a 30% reduction in the weight of the ovaries, shortened reproductive life span and formation of multiple cysts in the tissues lining the uterus.

There can no longer be any doubt that dioxin in very low exposures during early development in mammals can dramatically alter sexual development. The public health implications are enormous.

This Congress seems in a mood to crucify EPA scientists for reaching politically incorrect conclusions about dioxin. In an earlier time (1632), a scientist like Galileo, threatened by powerful religious zealots of his day, saved himself by recanting. Will EPA scientists be forced to do the same?
From Rachel's Environment & Health Weekly.]