Takata has updated the composition of an air bag propellant that contains a volatile chemical at the center of a recall of millions of vehicles around the globe, according to Reuters, citing a Takata official, who did not want to be named.

The official said that ammonium nitrate remained a "part of the mix," and that the shift was part of its process of "kaizen," or continual improvement.

Takata believed the new composition was safer than the one used previously.

"There is no admission of a defect with the original version. There has not been any finding that ammonium nitrate or the earlier composition was somehow flawed. We changed the composition in an effort to improve quality," the official added.

The company said they used the modified mix in replacement bags fitted in vehicles brought in during the recalls, but failed to mention when the change was made or in which cars

The official also didn't mention how many vehicles' air bags with the new propellant have been installed and whether or not the new mix was cheaper than the previous one, according to Reuters.

"There have been no problems with the new versions so far," he said.

Takata said the original version of the compound, when improperly processed or exposed to moisture, can cause the inflators to explode with "excessive force," thus spraying metal shards inside the vehicle. The air bags, used by a number of the top automakers around the world, have been linked to at least four deaths so far in the U.S. and multiple recalls since 2008.

Takata has made more than 100 million inflators since 2000, according to company data. Since 2008, 17 million cars equipped with its air bags have been recalled, including 11 million in the U.S.

Chrysler announced Wednesday that it would begin replacing potentially defective air bag inflators made by Takta in more than 317,000 vehicles in early December, according to NBC News.

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