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No 'Safe' Levels for Chemical Hormones?

Endocrine disruptors may be dangerous even at minute levels, government now says

WEDNESDAY, May 16 (HealthScout) -- Chemicals that mimic male and female hormones may not be safe even at levels the government now labels safe, a government panel suggests.

The chemicals are called endocrine disruptors, and studies show that some of these hormone-like substances may be harming the reproductive systems or the unborn in animals at levels well below the "no effect" ones defined by previous testing.

The Environmental Protection Agency (EPA) asked the National Toxicology Program to review chemicals that seem to provoke an endocrine reaction, says Ronald Melnick, who led the review panel and is a senior toxicologist for the National Institute of Environmental Health Sciences (NIEHS) in Research Triangle Park, N.C. "These chemicals, present in the environment, might act as a natural hormone, like estrogen or testosterone, or they might block the effect of that hormone."

"The issue that came up is: Are there effects at low doses from these chemicals that would not be picked up by the standard testing paradigm?" Melnick poses. "What's come up in the literature in recent years seems to show that at lower doses, below which the scientists have determined was a 'no effect' level, there still might be effects going on."

Controversy surrounds environmental estrogens and testosterones, Melnick adds. They are found naturally in some plants, and they are also created by manufacturers and used in plastics, insecticides and make-up. The synthetic chemicals can have a profound effect on the hormonal systems of animals or their young, previous research shows. Changes in the size and weight of reproductive organs, like the uterus or the prostate, have been linked to the chemicals. These chemicals can last for years in the environment and may collect in the fat tissue of animals and humans.

To get a handle on the issue, the National Toxicology Panel asked a group of outside experts to review published and ongoing research on endocrine disrupters, Melnick explains. "What they found was there was evidence of low-dose effects." The report concludes that experts need to figure out at what levels these chemicals can be considered safe.

The panel's report doesn't go far enough, says the executive director of the Children's Environmental Health Network in Washington, D.C.

"These are not problems that we want to wait for a smoking gun to appear before we regulate these chemicals," says Daniel Swartz. "If we are talking about very low levels of environmental estrogens causing fertility problems in animals, that strikes me as a problem. And even before all the evidence is in, that should force us to take some precautionary measures now."

"I don't think we know how serious this problem is," Swartz adds. "You are seeing these effects at relatively low levels from chemicals that persist for a long time in the environment, and we are talking about plastics and insecticides, which contain these endocrine disruptors. Even if we stopped right now, we might still see harmful effects for decades."

What To Do

The solution, Swartz says, is to get the synthetic chemicals off the market and help industry invest in research and development to make the transition. "If you are not getting any health benefit [from these chemicals], and there is some evidence of health risk, then let's get this stuff off the market," he says.

If you're interested in seeing the report on Endocrine Disruptors, you can find it at the National Institute of Environmental Health Sciences. Public comment on the report will be provided to the EPA, which provides more information on endocrine disruptors.

You may also want to read these other HealthScout stories on endocrine disruptors.

SOURCES: Interviews with Ronald Melnick, Ph.D., senior toxicologist, National Institute of Environmental Health Sciences (NIEHS), Research Triangle Park, North Carolina; Daniel Swartz, executive director, Children's Environmental Health Network, Washington, D.C.; May 15, 2001 NIEHS Press Release
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