Firefighters in Connecticut are seeking millions from 3M, DuPont and other companies for being exposed to toxic levels of "forever chemicals" in firefighting gear.

The firefighters say they have "experienced subclinical cellular changes in their bodies, which put them at increased risk of developing adverse health conditions, including but not limited to various cancers" due to the presence of PFAS chemicals in their protective wear, according to a federal class-action lawsuit filed this week.

Maplewood-based 3M said in a statement the company will "address PFAS litigation by defending itself in court or through negotiated resolutions, all as appropriate."

"As the science and technology of PFAS, societal and regulatory expectations, and our expectations of ourselves have evolved, so has how we manage PFAS," 3M said.

The lawsuit, brought by several firefighter unions and individual firefighters, names nearly two dozen chemical companies and manufacturers such as Honeywell and Gore as defendants. The suit seeks more than $5 million for violations of the Connecticut Product Liability Act.

"Defendants knew the equipment, materials and chemicals to be unsafe but represented the opposite," the suit states, and companies failed to warn about "specific, substantial risks to human health, profiting immensely."

3M struck a $12.5 billion settlement with water suppliers last year, though analysts have predicted 3M may have billions more to pay out in other PFAS cases, especially personal liability suits.

3M and other companies also face thousands of claims over firefighting foams that contained high levels of PFAS that reportedly caused cancer.

The company pioneered the use of PFAS in products such as Scotchgard and medical devices. The strong chemical bonds that make them useful for waterproofing and heat resistance — ideal for firefighting gear — also mean they don't break down in the environment and can accumulate in human bloodstreams. Studies have linked certain PFAS chemicals to various negative health outcomes.

3M plans to end the manufacture and sale of PFAS by the end of next year.