Scientists impaneled to reconsider the health hazards of dioxin urged Friday that the Environmental Protection Agency look beyond the chemical's cancer-causing potential and consider whether exposure to the substance could produce human reproductive, developmental and behavioral problems.
The advice came at the end of a conference in which scientists evaluated an eight-volume report that will be used by the EPA to rewrite regulations controlling dioxin--a substance considered by many experts to be one of the most dangerous byproducts of American industry.
Based largely on the panel's findings, the EPA will decide whether to elevate dioxin from a probable to a known carcinogen.
But members indicated Friday that they consider other potential hazards even more serious than cancer. Among them, they said, are reproductive and developmental defects that could be caused by dioxin exposure.
Edward Bresnick, a toxicologist at the Dartmouth Medical School, predicted that "10 years down the road, the impact of dioxin is going to be behavioral, an area where we have absolutely no data at all."
Extensive studies long ago established that dioxin, produced in massive amounts by the paper industry as well as in the combustion of industrial wastes and domestic trash, causes cancer in laboratory animals.
Other studies have linked dioxin to abnormalities in animals' brains and endocrine glands and to reduced testosterone levels in humans.
Dioxin is an ubiquitous substance in the human environment--coming from foods and volcanoes as well as domestic and industrial waste. But the production of dioxin and dioxin-like substances are of particular concern in the paper industry--where they result from the use of chlorine to bleach paper.
In the mid-1980s, the EPA set some standards controlling the amount of dioxin that could be discharged by industry into soil and water. But those regulations have been in dispute for almost a decade.
Last year, EPA Administrator William K. Reilly ordered a reappraisal of dioxin risks after new research indicated the chemical might be less dangerous than previously believed.
News of the research spurred intense pressure from the paper and chlorine industries for relaxed standards, while dubious environmentalists continued to press for more stringent regulations.
One of the chief points of contention over dioxin has been whether there is any level at which the substance is harmless. And some committee members expressed concern Friday that the public could be at risk even from relatively low levels.
It is possible, said Thomas Webster of Queens College's Center for the Biology of Natural Systems, that "we may already have body burden levels that are problematic from various points of view." But scientists evaluating the eight-volume EPA draft report here this week did not attempt to resolve that question.
To determine whether there is a minute acceptable exposure to dioxin "is a very, very difficult, if not, impossible, question to answer," said Curtis Klaassen, a University of Kansas toxicologist who chaired the committee. The volumes examined by the panel were drafted by independent experts over the last several months. EPA staff members will incorporate the comments from the evaluation and submit the agency's proposed new dioxin policy to its Science Advisory Board.
After a 90-day public comment period next year, the agency plans to issue its revised dioxin regulations.
There seemed to be nothing in the panel's evaluation to suggest any relaxation of federal standards.