WASHINGTON — President Trump has tapped Nancy B. Beck, a former chemical industry executive, to lead the Consumer Product Safety Commission, an independent federal agency charged with protecting the public against dangers like toxic substances in products.

Dr. Beck previously led the Environmental Protection Agency’s office of chemical safety, a position she came to after serving as the senior director of regulatory science policy at the American Chemistry Council, a lobbying group for the chemical industry.

Democrats and environmental groups on Tuesday criticized Dr. Beck’s nomination as chair of the commission and accused her of using her previous government positions to advance the agenda of the chemical industry.

During her time at the E.P.A., Dr. Beck oversaw the rewriting of an Obama-era rule in 2017 on a class of chemicals known as perfluoroalkyl and polyfluoroalkyl substances, or PFAS, that are linked to birth defects, in a way that would make them harder to regulate. She also helped scale back proposed bans on other substances like asbestos and methylene chloride, a deadly chemical found in paint thinners, in favor of limited restrictions.