by Sharon Lerner

For decades, Republican lawmakers and industry lobbyists have tried to chip away at the small program in the Environmental Protection Agency that measures the threat of toxic chemicals.

Most people don’t know IRIS, as the program is called, but it is the scientific engine of the agency that protects human health and the environment. Its scientists assess the toxicity of chemicals, estimating the amount of each that triggers cancer and other health effects. And these values serve as the independent, nonpartisan basis for the rules, regulations and permits that limit our exposure to toxic chemicals.

Now IRIS faces the gravest threat to its existence since it was created under President Ronald Reagan four decades ago.

Legislation introduced in Congress would prohibit the EPA from using any of IRIS’ hundreds of chemical assessments in environmental rules, regulations, enforcement actions and permits that limit the amount of pollution allowed into air and water. The EPA would also be forbidden from using them to map the health risks from toxic chemicals. The bills, filed in both the U.S. Senate and House of Representatives earlier this year, are championed by companies that make and use chemicals, along with industry groups that have long opposed environmental rules. If it becomes law, the “No IRIS Act,” as it’s called, would essentially bar the agency from carrying out its mission, experts told ProPublica.

“They’re trying to undermine the foundations for doing any kind of regulation,” said William Boyd, a professor at UCLA School of Law who specializes in environmental law. Boyd noted that IRIS reports on chemicals’ toxicity are the first step in the long process of creating legal protections from toxic pollutants in air and water.

“If you get rid of step one, you’re totally in the dark,” he said.

If the act passes, companies could even use the law to fight the enforcement of environmental rules that have long been on the books or permits that limit their toxic emissions, environmental lawyers told ProPublica.

The attack on IRIS has a good chance of succeeding at a time when Republicans are eager to support President Donald Trump’s agenda, according to environmental advocates who monitor Congress. The bills dovetail with the anti-regulatory efforts that have marked the second Trump administration, which has begun to dismantle climate protections, nominated industry insiders to top positions in the EPA and announced plans for unprecedented cuts that could slash the agency’s budget by 65%.

Project 2025, the ultraconservative playbook that has guided much of Trump’s second presidency, calls for the elimination of IRIS on the grounds that it “often sets ‘safe levels’ based on questionable science” and that its reviews result in “billions in economic costs.” The policy blueprint echoes industry claims that IRIS does not adequately reflect all of the research on chemicals; there are sometimes significant differences between the program’s conclusions and those of corporate-funded scientists.

IRIS has long been a target of industry and has at times been criticized by independent scientific bodies. More than a decade ago, for example, the National Academies of Sciences, Engineering, and Medicine took issue with the organization, length and clarity of IRIS reviews; a more recent report from the same group found that IRIS had made “significant progress” in addressing the problems.

IRIS’ work stands out in a world where much of the science on toxic chemicals is funded by corporations with a vested stake in them. Studies have shown that industry-funded science tends to be biased in favor of the sponsor’s products. But IRIS’ several dozen scientists do not have a financial interest in their findings. Their work has had a tangible impact on real people. The program’s calculations are the hard science that allow the agency to identify heightened disease risk due to chemicals in the air, water and land. And these revelations have, in some cases, led to stricter chemical regulations and grassroots efforts to curtail pollution.

IRIS, which stands for Integrated Risk Information........

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