WASHINGTON - A US regulator said on Wednesday it still believes that airbag inflators in 49 million US vehicles assembled by 13 automakers pose serious safety risks and it is considering issuing a recall.

The issue has been linked to one US fatality and seven injuries following an eight-year government investigation. If the recall proceeds, it would be the second-largest in US history.

The National Highway Traffic Safety Administration argued at a hearing in October that inflators produced by the two airbag manufacturers, ARC Automotive and Delphi Automotive, should be recalled because they may rupture and send metal fragments flying. After automakers raised objections in December, the agency did not immediately finalize its decision.

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The agency said on Wednesday it was reiterating and updating its initial determination first issued in September and giving automakers another 30 days to respond before it could formally demand recalls.

"Common sense demands acknowledging that metal shrapnel projecting at high speeds and causing injury or death presents an unreasonable risk to safety," NHTSA said.

Major automakers including General Motors, Toyota Motor and Volkswagen and the two airbag makers in December said they opposed NHTSA's bid to seek recalls.

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GM said on Wednesday it does "not believe the evidence at this time provides a basis for an additional recall beyond the vehicle population already included in existing recalls".

Reuters reported in October that at least 20 million GM vehicles could be affected, while Stellantis has 4.9 million vehicles with inflators at issue and has reported just one rupture, in 2009.

Stellantis said it was reviewing the NHTSA decision.

Automakers and manufacturers said the risks from the issue were exceedingly small, questioning the agency's analysis and rationale for seeking a recall.

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The inflators in question had been used in vehicles produced from 2000 through early 2018 by 13 automakers including Jaguar Land Rover, Ford, Mercedes-Benz, BMW, Hyundai, Kia and Porsche.

NHTSA first called for a voluntary recall in May 2023, but ARC rejected it.

GM, which in May 2023 recalled 1 million ARC inflators after a rupture resulted in facial injuries to a driver, said in December a recall would affect "as much as 15 percent of the over 300 million registered motor vehicles in the United States".

Delphi Automotive, part of Autoliv, manufactured approximately 11 million of the inflators through 2004 under a licensing agreement with ARC, which manufactured the remaining 40 million.