WASHINGTON—President Donald Trump’s pick to oversee chemical safety at the Environmental Protection Agency has withdrawn his name from consideration.

Michael Dourson, a toxicologist tapped to head the EPA’s Office of Chemical Safety and Pollution Prevention, has been one of the agency’s most controversial nominees because of his work as a consultant to the chemical industry. Democrats and environmentalists have criticized his research as skewed toward results desired by corporate clients.

While awaiting confirmation, Mr. Dourson started working at the EPA, as an adviser to Administrator Scott Pruitt, in a position that doesn't require a Senate vote. EPA spokespeople wouldn’t answer questions about whether he is staying in that role and declined to comment about his withdrawal.

Mr. Dourson replied to messages sent to his EPA email address Thursday, referring a request for comment to the website of the nonprofit he founded, Toxicology Excellence for Risk Assessment. The website says the group’s work was primarily for government groups and a third was for industries, and describes its projects as “transparent and/or collaborative.” Mr. Dourson didn’t address questions about his status at the EPA.

EPA officials have called Mr. Dourson a “highly qualified scientist,” and he received support from many Republicans before the nomination stalled. With the Republicans’ thin majority in the Senate, the nomination ran into trouble last month when two North Carolina Republicans said they wouldn’t vote for him. They cited his arguments for relaxed safety standards for trichloroethylene, one of the main chemicals found to have contaminated water and raised cancer risks at North Carolina’s Camp Lejeune military base.