Lawmakers find flaws with EPA’s chemical risk assessments

The arm of the Environmental Protection Agency that assesses the health effects of exposure to environmental contaminants is under attack by some Republicans in Congress. At a 6 September House committee hearing, lawmakers and private environmental consultants charged that the EPA’s Integrated Risk Information System (IRIS) relies on outdated or flawed studies to make its recommendations, which are weighted heavily in the EPA’s regulatory decision making.

Representative Andy Biggs (R-AZ), who cochaired the Science, Space, and Technology Committee hearing , said he “simply cannot support [IRIS] in its current form.” He said the program “has long suffered from a lack of scientific transparency and an inability to produce work in a timely manner. Even worse, IRIS appears to have been used by the previous administration as cover for unjustified and unscientific regulatory action.”

Biggs cited the case of Denka Performance Elastomer, a LaPlace, Louisiana, manufacturer of chloroprene, a precursor chemical to neoprene. In 2010 IRIS declared chloroprene a likely carcinogen and revised the acceptable inhalation limit for chloroprene downward to 0.2 μg/m³. Although the EPA couldn’t enforce a rule for that decreased exposure, it advised Denka, Louisiana environmental regulators, and the public of its newly determined limit. In January, Denka agreed to add $17.5 million worth of equipment to reduce its chloroprene emissions by 85%, even though, Biggs noted, the company had been in compliance with Clean Air Act regulations. Despite the agreement, nearby residents have filed a class-action lawsuit against the company and its previous owner, DuPont, that demands further emissions reductions.

Kenneth Mundt, health sciences practice leader at the environmental consulting firm Ramboll Environ US, testified in the hearing that IRIS’s chloroprene limit is 156 times more stringent than is scientifically justified. (Denka hired Ramboll to prepare an assessment on chloroprene exposure.) He said that among other “scientific shortfalls,” IRIS had failed to use standard EPA risk assessment methods that properly account for differences between mice and humans. The resulting “grossly exaggerated” estimate of cancer risks “unnecessarily triggers regulatory and legal action, as well as incites fear” in workers and residents, he said.

Biggs had unsuccessfully tried to amend an appropriations bill in July to terminate funding for IRIS. Rep. Don Beyer (D-VA) cited the failed effort as evidence that Biggs had called the hearing as “some sort of pretext for eliminating the program altogether.”

Although President Trump’s fiscal year 2018 budget proposal would cut the EPA’s science and technology budget by 38%, IRIS would largely be untouched. Budget documents note that IRIS assessments and scientific products are used by other EPA programs and the external risk management community.

Mundt and another consultant, James Bus, managing scientist at Exponent, testified that high-quality scientific studies had been ignored by IRIS in establishing inhalation exposure limits on chloroprene, formaldehyde, and trichloroethylene (TCE), a widely used industrial solvent.

Bus said the 2011 IRIS toxicological review of TCE relied on studies from a single university laboratory. The results of those studies were subsequently corrected three times and still couldn’t be replicated in two “much higher quality” studies, he said. Moreover, the data from the questionable studies were lost and weren’t available to the EPA. On the basis of the IRIS assessment, many Superfund cleanup sites that had been remediated of TCE to the earlier EPA standard may have to be reopened for additional cleanup at a potential cost of billions, Bus said.

There was no EPA witness to respond to Mundt’s and Bus’s charges. But in its 2014 TCE risk assessment , the EPA said the IRIS findings had undergone multiple levels of external peer review, including by the Office of Management and Budget, the EPA’s Science Advisory Board, and other federal agencies.

Thomas Burke, director of the risk sciences and public policy institute at Johns Hopkins University, came to IRIS’s defense. He called the program, which was established in 1985 by the Reagan administration, “a cornerstone of our national capacity to protect public health.” Burke also stressed the pervasiveness of TCE, noting that as a regulatory official in New Jersey, he had closed several municipal water supply systems due to TCE contamination.

IRIS has drawn increased scrutiny since the National Academies of Sciences, Engineering, and Medicine reviewed the program , specifically its assessment of formaldehyde, in 2011. The review had urged IRIS to establish clearer guidelines for deciding which chemicals to review, to explain the modeling processes used to develop risk estimates, and to better document estimations of toxicity values, among other measures.

In a letter to EPA administrator Scott Pruitt on 1 September, Peter Thorne, chair of the EPA’s Science Advisory Board, commended the progress IRIS has made. “The SAB has observed significant enhancements in the IRIS program over the past few years, with impactful changes over the past year, and marked progress over the past six months. The changes are so extensive and positive that they constitute a virtual reinvention of IRIS,” Thorne’s letter stated. In February the Government Accountability Office, which since 2009 has listed IRIS among federal programs “in need of broad-based transformation,” also noted that the EPA had made significant progress toward implementing the National Academies’ recommendations.