WASHINGTON — At his Senate confirmation hearing on Wednesday, Michael Dourson, President Donald Trump’s nominee to lead the federal office for chemical safety, defended his record against fierce attacks from Democrats, who accused him of downplaying the risks of potentially toxic chemicals.

"I have been objective in my work and applied sound science to come to my conclusions," said Dourson, a toxicologist who is Trump's pick to lead the Environmental Protection Agency’s chemical safety office.

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Democrats repeatedly pressed Dourson to commit to recusing himself from EPA decisions involving chemicals that industry players had paid for him to review, pointing out that his proposed standards for safe exposure were often much weaker than the EPA’s.

Dourson refused to state whether he would recuse himself, saying only that he would rely on EPA’s ethics officials to determine if such actions was necessary. According to his financial disclosure forms, Dourson hasn’t been directly paid by chemical companies within the past year, making it unlikely that he would have to recuse himself because of ethics laws, The New York Times reported.

In his opening remarks, Dourson promised to protect the American public, “including its most vulnerable.” He added that his research and consulting company, Toxicology Excellence for Risk Assessment, received only one-third of its funding from private industry, with the remainder coming from government sponsors.

But Dourson’s testimony did little to assuage Democrats. When Sen. Ed Markey of Massachusetts asked Dourson if he would weaken the EPA’s existing standards for 1,4-Dioxane — a solvent that the agency has classified as a likely carcinogen — Dourson said he would "bring new science and thinking into the agency."

Markey lashed out, saying that Dourson’s proposed standard for 1,4-Dioxane was 1,000 times higher than the EPA’s. "You’re not just an outlier on the science — you’re outrageous in how far from the mainstream of science you actually are," Markey said.

Throughout the hearing, Sen. John Barrasso, R-Wyo., the chairman of the Senate Committee on Environment and Public Works, repeatedly quoted praise for Dourson from toxicology professionals who described him as "highly qualified” and “a leader in the field of risk assessment."

Democrats do not have the votes to block Dourson's nomination, but if he passes out of committee — which didn't vote on his nomination Wednesday — they could threaten to prolong the nominating process by using a Senate procedure that requires 30 hours of debate for each nominee.