A former chemical-industry executive who fought against stronger regulations under the first Trump administration is returning to take critical roles at the Environmental Protection Agency, two people with knowledge of the appointment said, raising concerns of corporate influence on chemical safety regulations.

Nancy B. Beck, a toxicologist and former executive at the American Chemistry Council, the industry’s main trade group, is set to reprise a role helping to oversee chemical policy similar to the one she held from 2017 to 2021, though her exact title and scope of work has yet to be determined, the people said. The chemistry council represents dozens of chemical companies and major manufacturers.

Dr. Beck is credited with leading a wide-ranging pushback against chemical regulations during the first Trump administration, as well as what a subsequent internal investigation described as political interference in agency science and policymaking. She rewrote rules, for example, that made it harder to track the health consequences of a “forever chemical” linked to cancer, and therefore to regulate it.

She also helped scale back proposed bans on other substances like asbestos and methylene chloride, a harmful chemical found in paint thinners. Neither the E.P.A. nor Dr. Beck responded to requests for comment for this article.

Hunton Andrews Kurth, the law firm where Dr. Beck served most recently as director of regulatory science, said she was no longer with the firm. Dr. Beck is listed in the E.P.A. staff directory as a political appointee.

Dr. Beck is expected to be joined by Lynn Ann Dekleva, who also worked for the American Chemistry Council, who is set to return to a role helping to oversee new chemicals as deputy assistant administrator, though her title could still change, the people said. An environmental engineer by training, her career in the chemicals industry includes more than three decades at DuPont, the chemicals giant.

Recent reports released by the E.P.A.’s Office of Inspector General said that, under Dr. Dekleva, employees were pushed to approve new chemicals based on less stringent assessments and were retaliated against if they raised concerns.

Dr. Dekleva did not respond to requests for comment.

Chris Jahn, chief executive of the American Chemistry Council, said in a statement that the group looked forward “to working with all EPA staff in support of sound science” and policy to strengthen America’s competitiveness and create jobs.

The appointments of Dr. Beck and Dr. Dekleva to advisory or deputy jobs at the agency are not expected to require approval by Congress. Dr. Beck previously failed to win congressional approval to head the Consumer Product Safety Commission in 2020, after Democrats and environmental groups accused her of using her previous government positions to advance the chemical industry’s agenda.

“Nancy Beck, E.P.A.’s ‘toxics czar’ during the first Trump Administration, is back to fulfill the chemical industry’s wish list,” said Daniel Rosenberg, director of federal toxics policy at the Natural Resources Defense Council, an environmental advocacy group. “The weakening of health protections” from toxic chemicals “is just around the corner,” he said.

Over the past four years the Biden administration has tried to catch up on regulating the most dangerous chemicals on the market, as required under a law that was strengthened in 2016.

The Biden administration proposed or finalized restrictions on 10 dangerous chemicals, including trichloroethylene, a chemical used in cleaners and lubricants also linked to cancer, as well as asbestos, a heat- and fire-resistant mineral widely used in building materials that can cause cancer and lung disease. Currently, more than 80,000 chemicals on the market are not subject to environmental testing or regulation.

The Biden administration also set the first-ever federal standards for PFAS in drinking water, and designated two types of PFAS as hazardous substances under a law that shifts the responsibility for the cleanup of toxic sites from taxpayers to industry.

The chemicals industry has asked the Trump administration to roll back many of those rules. In a letter to Mr. Trump last month, a coalition of industry groups, including the chemistry council, called for a reversal of what they called the Biden administration’s “unscientific, sledgehammer approach” to chemical policy.

In the letter, the industry groups in particular ask the Trump administration to revisit PFAS drinking-water standards and the designation of the two PFAS chemicals as hazardous. They also press the E.P.A. to speed up its review of new chemicals, and to roll back its effort to place new regulations on existing chemicals, something chemical companies said was causing “confusion, duplication and overregulation.”