Last Updated: 2003-06-04 10:00:11 -0400 (Reuters Health)

WASHINGTON (Reuters) - A federal appeals court on Tuesday overturned a U.S. ban that prohibited testing pesticides on humans, opening the door for renewed debate on the practice.

The D.C. District Court of Appeals said that a directive by the Environmental Protection Administration (EPA) in December 2001 constituted a binding regulation because it was issued without notice or the opportunity for public comment, and therefore should be overruled.

The court reinstated the EPA's previous practice of considering third-party human studies, until the agency gathers public comment and issues a formal rule, a process that can take months or years.

Environmental groups said the ruling revives an ethical debate over whether chemical makers should test some products on humans to convince the EPA of their safety.

Erik Olson, attorney with the Natural Resources Defense Council, said the ruling "muddies the water" on human testing.

"We are very concerned that with EPA Administrator (Christine) Whitman leaving right now, the Bush administration may use this as an opening to accept unethical tests on humans," Olson said.

"There are a bunch of human studies that companies have done, which they may now ask the EPA to accept. There will be enormous political pressure on the EPA," he added.

Whitman, who resigned effective at the end of June, said in a December 2001 press release that the agency would no longer consider human test data submitted by pesticide companies. At the same time, the EPA asked the U.S. National Academy of Sciences for recommendations on whether such data should be allowed.

CropLife America, a trade group for chemical firms, filed a lawsuit to challenge the EPA ban. The group contends human test data can help determine pesticide safety and ensure that products needed by farmers are not overly restricted.

"Human clinical trials with pesticides are conducted to help refine the parameters and limits of risk and to increase the confidence in risk assessment so that risks are not underestimated or overestimated," said Jay Vroom, president of CropLife America.

That means pesticide usage can be better calibrated for safety and to produce high crop yields, Vroom added.

EPA officials had no immediate comment on the ruling.