The Biden-era limits were designed to reduce emissions of toxic pollutants, including a cancer-causing ingredient used in antifreeze and plastics.

© Mark Felix for The New York Times

The facility, in Colstrip, Mont., used a new E.P.A. system for requesting special waivers from President Trump.

© Kristina Barker for The New York Times

Products must state if they contain chemicals tied to cancer or other risks. As a result, manufacturers have pulled back from using the chemicals, researchers found.

The move would run counter to a Biden administration push to cut back on single-use plastic, which was considered a milestone.

Top political appointees are already at the E.P.A. preparing to erase the agency’s climate rules and pollution controls. Many of them have tried it before.

The findings give new insight into the dangers of urban wildfires that burn plastics and other chemicals in homes and property.

Health hazards from soot and smoke blown indoors onto furniture and walls can linger for months, researchers say: “Wind will get through every crack.”

How to understand the E.P.A.’s new warning about PFAS levels in sewage sludge.

Levels of PFAS in sewage sludge used as fertilizer can pose risks that sometimes exceed safety thresholds “by several orders of magnitude,” the agency said.

Researchers see a growing health danger from the vast plumes of pollution spawned by wildfires like the ones devastating Los Angeles.

It’s widely used because it can slow flames in ways that water can’t. But it also contains heavy metals and other harmful compounds.

Wastewater, even after treatment to make it drinkable, contains high levels of PFAS, according to researchers.

The agency obtained research from 3M in 2003 revealing that sewage sludge, the raw material for the fertilizer, carried toxic “forever chemicals.”