American Airlines employees allegedly experienced symptoms like rashes, headaches and respiratory issues following the launch of the airline's new uniforms in September 2016, according to a lawsuit, which was unsealed Tuesday in Chicago.

The lawsuit, which named about 40 employees, claims senior management at American became aware of issues with the Twin Hill uniforms following safety tests before the new outfits were implemented. The lawsuit contends that "American has knowingly tried to cover up the dangers posed by the the toxic Twin Hill uniforms."

One employee claimed in the suit that the new uniforms were a danger to others.

"I am not able to be around anybody in the new uniforms because the formaldehyde shuts down my respiratory system, and I will need an inhaler, oxygen and EpiPen and I am risking death by being around them," a flight attendant alleged in December 2016, according to the lawsuit.

While American Airlines was originally a defendant in the lawsuit along with Twin Hill, a judge decided to only pursue a case against Twin Hill, the Chicago Business Journal reports.

"This lawsuit has already been dismissed once, and we are confident that the facts will again result in a second dismissal," American Airlines told USA TODAY in a statement. "The amended complaint has been written in a sensationalized manner that does a disservice to American’s commitment to its team members, and to their continued health and safety."

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The airline pointed to a conclusion from the National Institute for Occupational Safety and Health, which said that "proximity exposure is unlikely to result in symptoms."

"We continue to believe that the current uniform is completely safe," the airline added. "In fact many team members, including senior executives, have worn the Twin Hill uniform safely and continue to do so today. Regardless, we are well underway with an alternative path to provide uniforms by new suppliers."

One thousand employees are currently wearing new uniforms from Land's End as part of a field test, according to Philly.com. A spokesperson said pilots this spring will don M&H Uniforms attire.