June 25 (Reuters) - DuPont ( DD ), 3M ( MMM ), Honeywell ( HON )

and 16 other defendants were sued on Tuesday by

Connecticut firefighters who said their protective gear was

contaminated by toxic "forever chemicals" linked to cancer.

Lawyers for the plaintiffs said they believed the proposed

class action filed in the New Haven, Connecticut federal court

is the first to exclusively target firefighter gear containing

per- and polyfluoroalkyl substances, or PFAS.

The Uniformed Professional Fire Fighters Association of

Connecticut, five other unions and five firefighters sued on

behalf of firefighters across the state, including cities such

as Hartford and Stamford.

They said jackets, pants and other "turnout gear" leeched

PFAS into firefighters through their skin, ingestion and

inhalation, and that more PFAS is absorbed as temperatures rise

and sweat builds up.

The plaintiffs said that led to "subclinical cellular

changes in their bodies which put them at increased risk of

developing adverse health conditions," justifying at least $5

million of damages for violations of Connecticut product

liability law.

DuPont ( DD ) and 3M ( MMM ) produced PFAS used in the protective gear,

while a Honeywell ( HON ) subsidiary was among the gear's sellers, and

failed to warn of the risks, the complaint said.

In a statement, DuPont ( DD ) said the lawsuit was without merit,

and that "we look forward to vigorously defending our record of

safety, health and environmental stewardship."

DuPont ( DD ) also said it has never manufactured PFOA and PFOS,

which are two types of PFAS that the plaintiffs alleged were

used in their gear.

Neither 3M ( MMM ) nor Honeywell ( HON ) immediately responded to requests

for comment.

PFAS are found in hundreds of consumer and commercial

products including cosmetics, non-stick pans and stain-resistant

clothing.

They earned the sobriquet "forever chemicals" because they

do not break down easily in the human body or environment.

PFAS have been linked to negative health effects including

higher cholesterol, low birth weights and reduced antibody

response to vaccines, as well as kidney and testicular cancer.

Last year, DuPont ( DD ), 3M ( MMM ) and two other companies reached

more than $11 billion of settlements to resolve claims that

firefighting foam and other products containing their PFAS

polluted drinking water. None admitted wrongdoing.

The case is Uniformed Professional Fire Fighters Association

of Connecticut et al v 3M Co ( MMM ) et al, U.S. District Court,

District of Connecticut, No. 24-01101.