The EPA on Monday proposed overhauling guidelines for assessing whether chemicals or other substances pose cancer risks. The new procedures generally would permit higher exposure to the toxic substances, officials said.
For the first time, the agency also proposed supplemental guidelines for gauging particular risks to children. Children are more susceptible to some toxic chemicals than adults.
Environmental groups called the special guidelines for children a step in the right direction. But they warned that the general guidelines would allow industry to challenge assessments.
"Strongly pushed by industry, EPA is moving in the direction to regulate fewer chemicals as cancer-causing agents," said Erik D. Olson, a senior attorney for the Natural Resources Defense Council. "In the long run, it is going to have profoundly bad effects on public health."
The chemical and pesticide industries, whose products are often the focus of these cancer-risk assessments, applauded the approach. These industries have pressed the Environmental Protection Agency for years to give more weight to the difference between the ways humans and animals are affected by chemicals. Traditionally, the cancer-risk assessments have been based on tests on laboratory animals.
The new proposal would "emphasize the best available science to guide policy makers and to inform the public," said Chris VandenHeuvel, spokesman for the American Chemistry Council, which represents most large chemical makers.
The proposed guidelines reflect EPA Administrator Christie Whitman's effort to ground the agency's actions -- in this case, its decisions about where to set the limits on toxic chemicals in food, water and air -- in more thorough science. They were expected to be made final as early as this summer.
Under the new guidelines, the public would be given descriptions of the risks posed by chemicals and the ways in which individuals could be exposed to those risks.
Officials said that under the proposal, chemicals would be less likely to be assessed as having high cancer risks because government scientists would draw on broader scientific evidence when making their evaluations.
"More often than not, as we get better knowledge, it's likely that the estimates of the risks will be coming down," said William H. Farland, the EPA's acting deputy assistant administrator for science.
But Farland stressed that government scientists would fall back on the old system if there was too much uncertainty in the available scientific data.
"We will be no less public-health protective using this new approach, but it will be informed by more of the science," Farland said.
In fact, the additional data may provide government scientists with clues about population groups -- such as children -- that are more susceptible to developing cancer from particular chemicals.
"There might be a higher risk for a subpopulation as the general risk goes down," said James Cogliano, chairman of the EPA's cancer guidelines writing group.
A recently completed cancer-risk assessment for chloroform, a chemical produced when chlorine is used to treat drinking water, serves as an example of how EPA scientists would use the new guidelines, Farland said.
Because chloroform caused cancer in laboratory animals, it probably would have been judged a carcinogen under the old rules. But EPA scientists looked at how chloroform causes cancer and determined that there was no cancer risk unless certain organs were damaged, Farland said. So chloroform was judged to be a cancer risk only in high doses.
Olson said these kinds of procedures give industry an upper hand. "The burden of proof comes on EPA to show industry arguments aren't valid," Olson said.
And most of EPA's data, he said, come from studies funded by companies trying to keep their chemicals from being labeled as carcinogens.
Farland dismissed the concern that industry would have more influence over the process. He stressed that under the new guidelines, government scientists would analyze a wide variety of information from government agencies and academic institutions. The evaluations would also be subject to peer review.