The Environmental Protection Agency issued formal guidelines yesterday for using information culled from tests that expose human subjects to toxic pesticides, a subject that had triggered intense disagreement over research ethics.

The proposed rules, which will be subject to public comment for 90 days before taking effect next year, would prohibit intentionally dosing pregnant women and children with pesticides, and establish an independent Human Studies Review Board to judge industry-sponsored and federal studies.

"This is a landmark regulation on human studies," Jim Jones, director of the EPA's Office of Pesticide Programs, told reporters. "We want to send the message clearly that certain kinds of human research can never be acceptable."

Some medical experts and lawmakers, however, said the standards fell short because they would still permit researchers to observe pregnant women's and children's everyday exposure to toxins and would allow the EPA to rely on the results of earlier studies that did not conform to the new guidelines.

Alan H. Lockwood, a University of Buffalo neurology professor who heads Physicians for Social Responsibility's environment and health committee, noted that a National Academy of Sciences panel wrote in 2004, "Studies that do not meet the highest scientific and ethical standards should not be carried out or accepted by EPA."

"That's the ethical standard that should be met," Lockwood said.

Jones said the agency's decision to accept studies conducted in the past reflects "the realities that an existing study cannot do things to get into compliance with" the proposed new guidelines.

Until President Bill Clinton imposed a moratorium in 1998, federal officials allowed manufacturers to conduct pesticide experiments on humans on the grounds that they provided a clearer picture of how pesticides could affect the environment and public health. President Bush initially backed the moratorium, but his administration abandoned it in 2003 to satisfy a court ruling in favor of pesticide makers, which argued that the federal government had not fully engaged the public before banning use of the information. EPA officials now consider data from human experiments on a case-by-case basis when judging whether to approve pesticides.

Pesticide makers hailed the new rules.

"We haven't seen this proposed rule, but we believe it has the potential to establish ethical and scientific safeguards and uniform standards to protect research subjects and improve the risk assessment process," said Jay Vroom, who represents major pesticide manufacturers as president of CropLife America.

But Sen. Barbara Boxer (D-Calif.), who has been pushing the EPA for months to adopt stricter guidelines, also said she had not yet seen the proposed rule but was concerned that it would mirror the most recent draft, which she considered inadequate. EPA officials did not make copies of the new guidelines available yesterday but described them in a news conference.

"A proposed rule on human pesticide testing that fails to protect children and families should be shelved immediately. A protective rule must be issued in its place," Boxer said.