Bloomberg Law
Aug. 31, 2020, 10:01 AM

Dueling EPA Chemical Numbers to Spur ‘Shopping’ for Helpful Data

Pat Rizzuto
Pat Rizzuto

Emerging EPA data that describes chemicals’ hazardous potential is expected to clash with older data about the same chemicals from another part of the agency—a conflict attorneys and analysts say will spur “shopping” for numbers that serve particular interests.

Adding to the confusion are disagreements about whether the older or newer data is more accurate. Industry groups are praising the EPA’s chemical office for producing long-overdue updates based on sound science. But others—including a former agency scientist who offered a rare insider’s perspective—are criticizing that office for producing numbers that favor industry and underestimate risks.

The conflict involves toxicity values, or numbers that depict amounts of potentially harmful chemicals. The Environmental Protection Agency, along with state and local officials, use these values to determine air, water, waste, and other regulations. Companies use them to decide how to manage chemicals at their facilities.

The chemicals office is, for the first time, releasing its own toxicity values, as part of the risk evaluations required by the amended Toxic Substances Control Act. The new numbers are expected to clash with other toxicity values, some decades old, in a program run by the EPA’s research office called the Integrated Risk Information System (IRIS).

Having multiple toxicity numbers for the same chemical will “lead to venue shopping to get the number that does what you wanted it to do,” said George M. Gray, who served as assistant administrator for research and development at the EPA under former President George W. Bush.

Millions of Dollars at Stake

Nearly a dozen scientists and attorneys echoed Gray’s conclusions. Martha E. Marrapese, a partner in Wiley Rein LLP’s Washington, D.C. office specializing in chemical regulations, acknowledged that “if the up-to-date number is advantageous to my client, I’d advocate for change.”

But she questioned the extent to which attorneys would play a numbers game. “If people think forum shopping’s going to help them, I don’t think so—TSCA’s too rigorous,” she said, referring to the law’s scientific requirements.

Millions of dollars could hinge on a toxicity value, according to Ted Simon, a toxicological consultant at Ted Simon LLC who’s helped companies reduce cleanup costs. The number a regulator selects for remediation could, for example, determine how much money must be spent to clean up a contaminated site, he said.

Some toxicity values are so strict that, for example, no one can afford to clean up old dry cleaners, said Kevin Murray, a partner in Holland and Hart LLP’s Salt Lake City office who focuses on Superfund and other waste regulations. Readily available, cheaper technology might do the job if credible scientific data could show the chemicals at abandoned dry cleaners were less hazardous, he said.

TSCA Numbers Criticized

The American Chemistry Council, which has long criticized IRIS’ procedures and numbers, is looking forward to having updated toxicity values.

The chemical office’s numbers are based on TSCA-required criteria that include using the best available science and procedures that allow people outside the EPA to understand how the agency reached its conclusions, said Michael P. Walls, the council’s vice president of regulatory and technical affairs.

Marrapese also would welcome more current toxicity data. “To the extent we need updated values to protect public health, the TSCA numbers could be a good thing,” she said.

Others are raising concerns.

A scientist who left the agency earlier this year and is familiar with the agency’s risk assessments described most of the TSCA numbers as “catastrophically poor.” The scientist said the numbers aren’t driven by science but by political appointees, many of whom have worked for industry, as well as by agency staff within departments that work closely with the industry and federal facilities subject to the EPA’s regulations.

TSCA risk assessors were told, for example, to omit health information that showed a chemical could harm IQ or a baby’s development, the scientist said. Staff also were told what conclusions the risk evaluation should reach, and “people would try to come at it seven different ways to get the number,” said the scientist, who isn’t authorized to describe internal agency deliberations.

Responding to the allegations, EPA spokeswoman Molly Block said that the agency’s offices, “from chemical safety and pollution prevention, to research and development, to water to air and radiation, use the best available science to fulfill the agency’s mission of protecting human health and the environment.”

‘This Is the Ball Game’

The EPA declined to answer specific questions about the potential for the two office’s toxicity values to clash, and how it might address that situation. IRIS hazard assessments and the chemical office’s risk evaluations aren’t directly comparable, Block said.

“The agency uses the best available science that addresses the relevant statutory requirements at the time of decision making,” she said.

But Bob Sussman, an attorney who represents the Safer Chemicals Healthy Families coalition, said the EPA’s chemical office is using multiple, often subtle, omissions and criteria to arrive at toxicity values that underestimate chemical hazards. Its numbers have generally been less protective than those from the IRIS program, he said.

Sometimes, the chemical office’s subtle choices mean it proposes toxicity values that are 1,000 times higher than they should be, Sussman said. Then, when the EPA takes the next step and uses those numbers to craft regulations, “that’s where the chickens will come home to roost,” he said.

Some workers may be protected, others may not be, and others won’t get the extent of protection they need, he said.

“These are enormously consequential calculations. They may seem arcane, but for public health protection, this is the ball game,” he said.


The EPA has already issued a final verdict on two chemicals, but the evaluations don’t offer much insight into how similar or different the numbers from the IRIS program and chemical office will be.

Penelope Fenner-Crisp, a private consultant who worked in the agency’s water, pesticide, and chemical offices 20 years ago, compared the IRIS values to similar numbers in the first 10 draft or final TSCA risk evaluations, and found them fairly consistent.

But the chemical office concluded that the paint stripping solvent methylene chloride was a slightly less powerful carcinogen than IRIS had estimated in 2011, and tweaked its cancer potency number.

The EPA’s own science advisers questioned why the cancer number for methylene chloride was “less protective” than what IRIS and the Occupational Safety and Health Administration previously calculated. The agency’s final analysis and response to its advisers provided details about why the chemicals office concluded that “previous assessments were more conservative than necessary.”

The IRIS program didn’t have toxicity values for a dry cleaning and degreasing solvent, 1-bromopropane, which the EPA said needs regulating because it poses too great a chance of injuring workers and consumers.

Evaluations of eight additional chemicals are set for publication this year, with at least 22 more coming in future years, because the 2016 TSCA amendments require a steady stream of these analyses. Of the 30 chemicals remaining, 20 have IRIS values, and 10 have IRIS values that are at least three decades old.

‘Full of Choices’

New scientific data will drive some differences between the dueling toxicity values, but so will human nature, said Gray, a senior scholar at George Washington University’s Regulatory Studies Center who used to oversee the EPA’s IRIS program.

“Risk assessment is full of choices that have to be made along the line. Very smart people trying for same goal will make different choices,” he said.

The EPA could help state agencies and companies by describing how it will handle potential discrepancies between the numbers from the chemicals office and the research office, attorneys and scientists say.

Agencies, companies, and states should closely examine the updated toxicity values before deciding to use them, said Kimberly Wise White, a senior director at the chemistry council.

“Each toxicity value should be evaluated for its relevancy and usefulness for the specific regulatory decision,” she said. “I don’t think any state agency should just use it because it’s new.”

To contact the reporter on this story: Pat Rizzuto in Washington at

To contact the editor responsible for this story: Rebecca Baker at