WASHINGTON (AP) — The Biden administration has initiated a formal evaluation of risks posed by vinyl chloride, the cancer-causing chemical that burned in a towering plume of toxic black smoke following a fiery train derailment earlier this year in eastern Ohio.

The Environmental Protection Agency said it will review risks posed by a handful of chemicals, including vinyl chloride, which is used to make a variety of plastic products, including pipes, wire and packaging materials. The chemical is found in polyvinyl chloride plastic, better known as PVC.

The EPA said it will study vinyl chloride to determine whether it poses an “unreasonable risk to human health or the environment,″ a process that would take at least three years.

Vinyl chloride is one of five chemicals the agency is reviewing, including four that are used to make plastics. Other chemicals set for review under the federal Toxic Substances Control Act include acetaldehyde, acrylonitrile, benzenamine, and a compound known as MBOCA.

“Under the Biden-Harris administration, EPA has made significant progress … to strengthen our nation’s chemical safety laws after years of mismanagement and delay. Today marks an important step forward,” said Michal Freedhoff, assistant EPA administrator for chemical safety and pollution prevention.

Studying the safety of vinyl chloride and other chemicals that have been in use for decades “is key to better-protecting people from toxic exposure,” Freedhoff said in a statement.

Environmental and public health activists welcomed the announcement, calling the review long overdue.

“Vinyl chloride was classified as a human carcinogen in 1974. That same year, the federal government wisely banned the use of vinyl chloride in hair sprays, refrigerants, cosmetics and drugs,” said Judith Enck, a former EPA regional administrator and president of the advocacy group Beyond Plastics.

Enck and other advocates had called the toxic train derailment in East Palestine, Ohio, a warning that the U.S. must ban petrochemicals such as vinyl chloride.

Jess Conard, an East Palestine resident who now works as a regional director for Beyond Plastics, said EPA was making the right decision.

“Vinyl chloride is transported by rail all over the country and is the primary chemical that has contaminated not just my home in East Palestine, Ohio, but other communities where PVC and vinyl chloride manufacturing facilities exist,” Conard said in a statement.

“If you live along the rail line, you are at risk for the same fate (as East Palestine) with every passing train that is transporting toxic chemicals,” she said. Conard faulted what she called “an insatiable demand” by Americans for plastic products that has “driven the need for increased transport of these hazardous substances, placing communities like mine at risk every single day.″

Vinyl chloride is found in plastic PVC pipes, as well as vinyl siding, packaging and a range of consumer goods, including furniture, car parts, shower curtains and toys used by children and pets.

Inhalation of vinyl chloride has been linked to liver cancer and other health problems, according to the National Cancer Institute, and its use has long been banned in cosmetics, hair spray and other personal products. PVC plastic is not a known or suspected carcinogen, the agency said.

The Vinyl Institute, a trade group that represents manufacturers, said it was prepared to work with EPA on the risk analysis.

The institute “has indicated our strong interest to be engaged in the process early, and to serve as a collaborative resource for the agency,” said Ned Monroe, the Vinyl Institute’s president and CEO.

“This is an opportunity to correct any misunderstanding about the regulation of vinyl chloride manufacturing and the safety of PVC products,” Monroe said. “We believe this risk evaluation will further assure that the production of vinyl chloride and use of PVC products are safe. Manufacturers of vinyl chloride adhere to some of the most stringent safety and environmental regulations in the chemical industry.”

Vinyl chloride monomer is an intermediary chemical found in PVC products that are used every day, Monroe said, including PVC pipes used for drinking water, vinyl windows and siding, and medical products such as IV blood bags.

Debate over vinyl chloride has simmered for years but gained a new urgency after the Feb. 3 derailment of a 50-car Norfolk Southern freight train in East Palestine. Three days later, emergency crews released toxic vinyl chloride from five tank cars and burned it to keep them from exploding.

That sent a billowing plume of black smoke over the town near the Pennsylvania border and prompted the evacuation of about half of its 5,000 residents. Nearly a year later, residents remain concerned about lingering impacts on health, even though state and federal officials say tests show the town’s air and water are safe.

The Feb. 6 burn sparked worries that it could have formed dioxins, a known carcinogen created from burning chlorinated carbon materials.

Since an evacuation order was lifted near the derailment site, vinyl chloride has not been found in the community at or above an intermediate screening level, the EPA said. The agency ordered testing for the highly toxic compounds after the derailment; results so far suggest there’s a low chance that dioxins were released following the derailment, the EPA said.

Daniel Rosenberg, director of federal toxics policy for the Natural Resources Defense Council, said vinyl chloride is highly toxic, “from manufacture to use and disposal — not to mention transport, as the community of East Palestine, Ohio, knows all too well. EPA should factor in all possible sources of exposure to vinyl chloride when assessing its risk.”