By a wide margin, the Senate voted yesterday to bar the Environmental Protection Agency from using tests exposing human subjects to toxic chemicals when deciding whether to approve the marketing of pesticides.

The Senate voted 60 to 37 in favor of an amendment sponsored by Sen. Barbara Boxer (D-Calif.) -- which came as lawmakers considered the EPA's annual spending bill -- that would impose a one-year moratorium, starting Oct. 1, on using such tests. Sixteen Republicans joined 44 Democrats in backing the measure; the House adopted identical language in May by voice vote.

Erik Olson, senior attorney of the Natural Resources Defense Council, an advocacy group that sued to force the EPA to regulate high-risk pesticides, said the fact that Catholic, Lutheran and Jewish groups all lobbied in favor of the ban cemented GOP opposition to human testing.

"There really is an emerging new coalition that opposes the Bush administration policy," Olson said. "This sends a very clear, strong signal to the administration that to continue to toe the line with the chemical industry is going to hurt them."

It remained unclear whether Boxer's language will make it into law as part of the EPA's final budget. By a vote of 57 to 40, the Senate passed a measure by Sen. Conrad Burns (R-Mont.), who supports some human pesticide studies, that would allow the agency to use such tests, provided they meet certain ethical standards and their benefits outweigh the risks they pose to volunteers.

The federal officials allowed industry to conduct such studies for years, but recently the government has sought to limit human pesticide testing. President Bill Clinton imposed a moratorium in 1998 that Bush lifted during his first term, and EPA officials now judge human pesticide studies on a case-by-case basis.

The agency has drafted regulations that would establish standards for using tests on children, pregnant women, newborns and other volunteers, but these rules do not include all the safeguards recommended in a 2004 study by the National Academies of Science that was commissioned by the administration. The EPA has yet to finalize the regulations, which will not take effect for several months.

Asked to comment on yesterday's vote, EPA spokeswoman Eryn Witcher said: "We continue work on drafting the first-ever rule to address the ethical and scientific issues surrounding human studies."

CropLife America, which represents the country's biggest pesticide manufacturers, issued a statement saying manufacturers are confident that lawmakers will ultimately allow some human testing to gauge the impact of pesticides on the environment.

"CropLife America believes that sound science and public health protections have affirmed the safety and ethics of human data studies," the statement read. "We look forward to a continued dialogue with the Congress, federal regulators and the scientific community on this important issue."