(Bloomberg) -- U.S. auto safety regulators are determiningwhether 70 million to 90 million more Takata Corp. air-baginflators should be recalled, Reuters reported, potentiallyexpanding the industry’s broadest ever safety crisis.

The inflators built with a chemical propellant called ammoniumnitrate may be recalled because they endanger drivers, Reutersreported, citing a person with knowledge of the matter. TheNational Highway Transportation Safety Administration isinvestigating all Takata inflators using ammonium nitrate andhasn’t found enough evidence to direct automakers to recalladditional inflators, spokesman Gordon Trowbridge told Reuters.Trowbridge didn’t immediately respond to an e-mail sent outsidenormal business hours.

Takata is cooperating fully with regulators and its customers,and continues to test inflators, build replacement air-bag kits andraise consumer awareness of recalled vehicles, spokesman HideyukiMatsumoto said. He declined to say how many inflators with ammoniumnitrate Takata has produced.

Related: Takata air-bag recall expanded as 10th deathlinked

NHTSA said in November it no longer had confidence in the safetyof ammonium nitrate propellant, which has been under scrutiny asTakata inflators have ruptured and sprayed shards of metal andplastic at motorists. The most recent expansion of recalls,announced last month, brought the total number of inflatorsrecalled to more than 28 million, according to NHTSA’s website.

Honda Motor Co., Takata’s biggest customer and a minorityshareholder, is not aware of whether 90 million more air bags needto be replaced, spokeswoman Yuka Abe said. The automaker’s priorityis to find out the root cause of the air bag inflator ruptures andreplace them as soon as possible, she said.

The Associated Press last week cited unidentified experts sayingthere could be as many as 50 million Takata air bag inflators incars that have yet to be called back for repairs.

Related: Latest air bag death said to show flaws in U.S.recall system

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