American Airlines has been at odds for months with the union that represents its flight attendants. The issue: new uniforms.

Employees say the garments have triggered allergic reactions and health issues including headaches, rashes and breathing problems. The union has demanded that American recall them.

But American and the company that supplies the uniforms, Twin Hill, have both said multiple lab tests have confirmed the clothes are completely safe -- though the airline has offered employees new uniform options in response to complaints.

Now, American (AAL) said it is ready to part ways with the clothing manufacturer.

Related: American Airlines flight attendants want new uniforms recalled

The airline said Wednesday that it will be ending its relationship with Twin Hill when their current contract expires in 2020. American again insisted that the uniforms are safe and that most of the company's 70,000 front-line employees have been pleased with them.

American said the decision to sever business ties with Twin Hill was "mutual."

Twin Hill responded in a statement Wednesday, saying its third-party tests confirm the fabrics it uses contain "no restricted chemicals." It said it has never been "presented with any evidence linking the uniforms to the symptoms reported."

The company added that it welcomed the opportunity to end its relationship with American Airlines because the employee complaints were creating a "reputational risk."

Twin Hill says it concluded that "the costs associated with serving American in the future would be unacceptable to our business, given the likelihood of continued unfounded allegations about the safety of our garments," the statement reads.

Since the airline introduced the uniforms last fall, the Association of Professional Flight Attendants said it has "received more than 3,500 reports of suspected reactions from members of our union."

The union said in a statement Wednesday that it's "pleased" with the decision to sever ties with Twin Hill.

"Management at American is taking a positive step by stating that front-line flight attendants and our union will play a key role as the process for delivering new uniforms goes forward," the union statement said.

Related: American Airlines uniform maker says its clothes are safe

According to the American memo, the airline has not yet selected a supplier to outfit its employees. It did say the new garments will be "based on our current design, but will feature new fabrics."

The airline added that because it offered alternative uniform options in response to the controversy, its crew members are wearing "many different versions of the uniform." Customers may be confused, American said.

American employees aren't the first to complain about Twin Hill's products. Alaska Air Group (ALK), which owns Alaska Airlines, dropped a deal with Twin Hill after its flight attendants complained about similar reactions to uniforms they were issued in 2011.

That incident lead to a lawsuit, which Twin Hill won after a court in Alaska asserted that Twin Hill's clothing "could not have been the cause of the alleged symptoms," the company said in its statement Wednesday.

Twin Hill also appeared to suggest that the Alaska Air case wrongly fueled concerns among American workers.

"The Alaska uniforms have been repeatedly referred to by American Airlines personnel and union leadership, primarily through social media and targeted press, to suggest a pattern of issues with our products," the company's statement reads. "The fact is, however, that scientists at the National Institute of Occupational Safety and Health, an agency of the U.S. Centers for Disease Control, determined that they could not relate the symptoms the Alaska flight attendants claimed to experience with the uniforms Twin Hill had produced."

Twin Hill is a unit of Tailored Brands (TLRD), which also owns retailer Men's Wearhouse.