The rules were revised under intense criticism from environmental groups, scientists and members of Congress after the disclosure that subjects in some earlier pesticide studies were unaware of what they were being exposed to and, in many cases, did not know why the testing was being done.

One study would have used $2 million from the chemical industry to measure the pesticide consumption of infants in low-income households in Florida.

In unveiling the new rules last week, the EPA promised full protection for those most at risk of unethical testing.

"We regard as unethical and would never conduct, support, require or approve any study involving intentional exposure of pregnant women, infants or children to a pesticide," the rule states.

But within the 30 pages of rules are clear-cut exceptions that permit:

-- Testing of "abused or neglected" children without permission from parents or guardians.

-- "Ethically deficient" human research if it is considered crucial to "protect public health."

-- More than minimal health risk to a subject if there is a "direct benefit" to the child being tested, and the parents or guardians agree.

-- EPA acceptance of overseas industry studies, which often are performed in countries that have minimal or no ethical standards for testing, as long as the tests are not done directly for the EPA.

The EPA provided little clarification this week in response to questions about the exemptions. In a written response, officials said that abused and neglected children were specifically singled out to create "additional protection" for them, although they did not elaborate.

They also denied there were any exceptions to the prohibitions on testing women and children. They added that the new rules met all the requirements set by Congress last spring and summer in a series of often heated hearings.