Chemical and consumer product manufacturer 3M has agreed to pay six billion dollars (£4.76 billion) to settle numerous lawsuits from US service members who say they experienced hearing loss or other serious injuries after using faulty earplugs made by the company.

The settlement, consisting of five billion dollars (£3.97 billion) in cash and one billion dollars (£0.79 billion) in 3M stock, will be made in payments that will run through to 2029.

The agreement announced by the Minnesota company on Tuesday marks a resolution to one of the largest mass torts in US history.

Hundreds of thousands of veterans and current service members have reportedly sued 3M and Aearo Technologies, a company that 3M acquired in 2008, over their Combat Arms Earplug products.

The service members alleged that a defective design allowed the products — which were intended to protect ears from close range firearms and other loud noises — to loosen slightly and allow hearing damage, according to Aylstock, Witkin, Kreis, & Overholtz PLLC, one of the law firms representing plaintiffs.

In an online summary about the Combat Arms Earplug litigation, the Florida-based law firm notes that 3M previously agreed to pay 9.1 million dollars (£7.21 million) to settle a lawsuit on behalf of the US government alleging the company knowingly supplied defective earplugs to the US military.

And since 2019, the firm added, 3M has lost 10 of 16 cases that have gone to trial — awarding millions of dollars to plaintiffs to date.

The Associated Press approached Aylstock, Witkin, Kreis, & Overholtz PLLC for comment on Tuesday’s agreement. In a statement to Bloomberg and other news outlets, lawyer Bryan Aylstock called the settlement a historic agreement and a “tremendous victory for the thousands of men and women who bravely served our country and returned home with life-altering hearing injuries”.

In Tuesday’s announcement, 3M maintained that the agreement — which includes all claims in Florida’s multi-district litigation, co-ordinated state court action in Minnesota, and potential future claims — was not an admission of liability.

“The products at issue in this litigation are safe and effective when used properly,” the company wrote. “3M is prepared to continue to defend itself in the litigation if certain agreed terms of the settlement agreement are not fulfilled.”

3M has previously tried to reduce exposure to the earplug litigation through bankruptcy court, the Wall Street Journal reported. In 2022, Aearo filed for bankruptcy as a separate company, accepting responsibility for claims, but the filing was later dismissed in US bankruptcy court.

Beyond the earplug litigation, 3M in June agreed to pay at least 10.3 billion dollars (£8.16 billion) to settle lawsuits over contamination of many US public drinking water systems with potentially harmful compounds.

The deal would compensate water providers for pollution with per- and polyfluorinated substances, also known as “forever chemicals”.

The agreement has not been finalised yet. Last month, 22 attorneys general urged a federal court to reject the proposed settlement, saying it lets manufacturer 3M off too easily.

They argue that the deal does not give individual water suppliers enough time to determine how much money they would get and, in some cases, could shift liability from the company to providers.

On Tuesday, New York Attorney General Letitia James said that 3M agreed to make significant changes to the settlement terms — which, as reflected in a proposed court order, include extending the deadline for eligible water systems to review the settlement and removing uncapped indemnity in favor of 3M.

Ms James, along with the other attorneys general, have now withdrawn their opposition, her office said on Tuesday.

Still, five attorneys general will also be filing an amicus letter expressing concerns of the amount and timeline of the settlement payment, California Attorney General Rob Bonta announced on Tuesday.

“3M has agreed to modify its original proposed settlement in critical ways that will benefit the American people,” Mr Bonta said in a statement.

“However, 3M declined to pay an amount that accurately reflects the extraordinary damage it has caused to public drinking water systems, and it declined to provide water suppliers the money to remediate that damage more quickly.”