Itching, rashes, headaches, and hives. Serious health problems, or a tempest in a teapot?

These are among the complaints leveled by some American Airlines flight attendants about their new uniforms rolled out in September for 70,000 American employees, including pilots, airport agents, mechanics, and baggage handlers. American has 8,000 workers based at its Philadelphia International Airport hub.

The Association of Professional Flight Attendants (APFA), the union representing 25,500 American flight attendants, said it has received 2,300 reports from members about reactions to the uniforms, including burning skin, eye irritation, and respiratory problems. The union  demanded that American recall the uniforms and filed a grievance with the airline.

Last week, the clothing manufacturer Twin Hill, a subsidiary of Houston-based Men's Wearhouse, fired off a letter to APFA leaders saying that testing has showed the uniforms to be safe. Nevertheless, the company said it wants to find an amicable solution.

Twin Hill senior vice president Daryl Stilley invited the union to visit the company's Houston warehouse, along with American officials, to conduct joint chemical testing of the uniforms. "We don't expect you to take our word for it - we encourage you to see for yourself," Stilley said. The letter said a visit was scheduled three times in the last two months, and each time APFA canceled at the last moment.

Since the uniforms were rolled out, American's flight attendants' union is the only employee group to make formal injury claims. American spokesman Matt Miller said about 450 employees have filed reports with the airline telling of a bad reaction, including 350 flight attendants. "There have been some employees who have expressed concerns and had an allergic reaction to the uniform material," Miller said. "We're encouraging anyone who has experienced a negative reaction to file a report so we can address each concern individually."

This is not the first time Twin Hill has had a run-in with airline flight attendants.

In 2013, Alaska Airlines contracted with Lands' End Business Outfitters for new uniforms for flight attendants and customer service and cargo agents after complaints of adverse reactions to Twin Hill uniforms. "When employees began complaining of symptoms, we offered alternative uniform pieces, and then ultimately provided the new uniforms," an Alaska spokeswoman said.

Separately, 164 Alaska Airlines flight attendants filed a lawsuit, alleging that the Twin Hill uniforms caused various health problems. Ultimately, a court rejected the flight attendants' claims, saying the National Institute for Occupational Safety and Health, part of the Centers for Disease Control and Prevention, was "not able to relate the symptoms" to the uniforms.

American Airlines has made a non-wool version available to workers with sensitivity to wool. The manufacturer said it is designing 100 percent cotton garments as another alternative. "We are committed to ensuring that every single AA employee has a uniform that is both safe and comfortable," Stilley wrote.

Miller said American has permitted the affected employees to continue wearing their old uniforms, and to purchase certain uniform items at department stores. American will reimburse employees for the costs, he said.

"We are making options, and alternatives available, for anyone who has concerns," Miller said. "But from our point of view, the uniforms are safe. We have conducted three rounds of testing, one before the uniform roll out, and two after the rollout. All that testing has demonstrated the uniforms are safe and they meet the industry benchmark for garment safety."

American plans to conduct an additional round of testing, and does not plan to  recall the uniforms.

Shane Staples, spokesman for the flight attendants, said the union has a toxicologist "working on our behalf. We feel that it's premature to pull [uniform] samples until we have agreed on a testing protocol. We want to make sure that the joint testing that we do with the company will elicit good, solid information.

"We're trying to get the company to agree to allow our toxicologist to have some input on that testing protocol. That's the sticking point right now," he said.