Citing a recent ProPublica investigation, Sen. Richard Blumenthal, D-Conn., urged the Environmental Protection Agency in a letter this week to issue a final report on the health risks of formaldehyde that is “science-based” and “as strong as possible,” adding that “the agency has an obligation to protect the public from the chemical.”

Formaldehyde, used for everything from preserving dead bodies to binding wood products and producing plastic, is extremely widespread and causes far more cancer than any toxic air pollutant. ProPublica’s analysis of EPA air pollution data showed that, in every census block in the U.S., the risk of getting cancer from a lifetime of exposure to formaldehyde in outdoor air is higher than the goal the agency has set for public exposure to air pollutants.

The EPA issued a draft of the formaldehyde risk evaluation in March and, after receiving feedback from the public and a committee of experts, is expected to release the final version by the end of the year. The forthcoming evaluation will be used to inform future restrictions the agency puts on the chemical. But the ProPublica investigation found that the draft version of the report used unusual techniques to underestimate the risk posed by formaldehyde.

In one case, the agency determined whether concentrations of formaldehyde in outdoor air posed an “unreasonable risk” — a level that requires the agency to address it — not by measuring them against a health-based standard, but rather by comparing them to the highest level of the chemical measured outdoors in a five-year period. The measurement the agency chose as a reference point was a fluke, ProPublica found, and had not met the quality control standards of the local air monitoring body.

The EPA did not immediately respond to questions from ProPublica about Sen. Blumenthal’s letter and when the agency plans to release its final report.

Good journalism makes a difference:

The EPA is evaluating the health risks of formaldehyde under the Toxic Substances Control Act, the main federal law that governs chemicals. That process typically relies on toxicity estimates calculated by a separate division of the agency. In the case of formaldehyde, the EPA released the final toxicity values in August of this year, decades after it began the process of calculating them. Throughout that time, companies that make and use the chemical — and could lose money if it is restricted — criticised the agency’s numbers and worked to delay their release.

Some industry-affiliated members of the expert committee that reviewed the draft evaluation of formaldehyde this year have continued to find fault with the EPA’s toxicity estimates and have suggested that the agency weaken them in its final report.

In his letter, Blumenthal advised EPA Administrator Michael Regan against taking this route. “Throughout your tenure, EPA has been steadfast in upholding its vital mission of protecting human health and the environment,” he wrote. “I urge you to continue this commitment and issue a final risk evaluation for formaldehyde that is rooted in the best available science.”