WASHINGTON (AP) — North Carolina's two Republican senators said Wednesday they oppose President Donald Trump's pick to oversee chemical safety at the Environmental Protection Agency, putting his nomination at serious risk.

Senators Richard Burr and Thom Tillis issued statements saying they will vote against Michael L. Dourson to serve as head of EPA's Office of Chemical Safety and Pollution Prevention.

Environmentalists and Senate Democrats have vehemently opposed Dourson, a toxicologist with close ties to the chemical industry. That means only one more Republican "no" vote would likely be needed to torpedo his nomination.

The White House and EPA did not respond to requests for comment Wednesday evening. Despite his lack of Senate confirmation, Dourson has already been working at the agency as a senior adviser to EPA Administrator Scott Pruitt.

The Associated Press reported in September that Dourson has for years accepted payments for criticizing studies that raised concerns about the safety of his clients' products, according to a review of financial records and his published work.

Past corporate clients of Dourson and of a research group he ran include Dow Chemical Co., Koch Industries Inc. and Chevron Corp. His research has also been underwritten by industry trade and lobbying groups representing the makers of plastics, pesticides, processed foods and cigarettes.

Burr and Tillis, both of whom are considered reliably pro-business conservatives, cited Dourson's past work and worries among their home-state constituents about tainted drinking water in opposing his nomination.

"Over the last several weeks, Senator Tillis has done his due diligence in reviewing Mr. Dourson's body of work," said statement said. "Senator Tillis still has serious concerns about his record and cannot support his nomination."

Marine veterans and their families blame decades-old contamination of wells at a North Carolina base with solvents and dry-cleaning chemicals for infant deaths and serious health problems that include cancer.

More recently, concerns have been raised about undisclosed discharges of chemicals used to manufacture Teflon and GoreTex into the Cape Fear River, a source of municipal drinking water for Wilmington and other southeastern North Carolina communities.

Dourson worked at the EPA for more than a decade, leaving in 1994 as the manager at a lab that assessed the health risks of exposure to chemicals. The following year, he founded Toxicology Excellence for Risk Assessment, a private toxicity evaluation nonprofit organization that tests chemicals and produces reports on which chemicals are hazardous in what quantities.

Dourson's views toward industry are consistent with others Trump has selected as top federal regulators. Among them is EPA Administrator Scott Pruitt, who in March overruled the findings of his agency's own scientists to reverse an effort to ban chlorpyrifos, one of the nation's most widely used pesticides.

Court records show Dourson and his work have often been called on when his corporate clients are seeking to fend off lawsuits.

DuPont was accused of polluting a West Virginia town with Perfluorooctanoic acid, or PFOA, a chemical that the company's internal tests had long ago concluded were toxic. Corporate officials discussed hiring Dourson as part of a strategy to defend themselves.

Dourson led a team that found in 2002 that PFOA levels up to 150 parts per billion were safe, a level higher than was found in testing of 188 private wells and springs.

That was also well above the 1 part per billion Dupont's own scientists had concluded could be considered safe years before. The EPA now says that only 70 parts per trillion of PFOA are acceptable — or only 0.05 percent of what Dourson's team said was safe.

DuPont and a former subsidiary, Chemours Co., later paid $761 million to settle 3,550 lawsuits stemming from its use of the chemical.

Chemours is the company whose spills of a chemical called GenX, a replacement for PFOA, are now at issue in North Carolina's Cape Fear River.

"I will not be supporting the nomination of Michael Dourson," said Burr, the state's senior senator. "With his record and our state's history of contamination at Camp Lejeune as well as the current GenX water issues in Wilmington, I am not confident he is the best choice for our country."

The stand was quickly praised by environmental advocacy groups that rarely find common ground with the two Tarheel Republicans.

"No one who has spent decades arguing on behalf of the chemical industry for weaker safety standards should be charged with reviewing chemicals for the EPA," said Scott Faber, a senior vice president for government affairs at the Environmental Working Group. "It would be like putting an arsonist in charge of the fire department."

___

Follow Associated Press environmental reporter Michael Biesecker at http://twitter.com/mbieseck