More American Airlines flight attendants say their uniforms are making them sick, according to a Fortune report.

In September, the company introduced new uniforms for the first time in 30 years, but it may have had a different effect than intended.

Shortly after the new uniform debut, more than 400 flight attendants began to allege the uniforms were making them sick, causing them hives and headaches, according to Fortune.

Now, Fortune reports more than 1,300 flight attendants have filed complaints.

After the initial complaints, the airline claimed the reaction was due to a wool allergy.

The Association of Professional Flight Attendants (APFA) found otherwise, according to Fortune.

The APFA carried out their own tests on the uniforms by clothes maker Twin Hills and said they found detectable traces of chemicals found in pesticides, fungicides and fertilizers.

The APFA said they'll continue to investigate the issue, and expect American Airlines and Twin Hills to do the same, according to Fortune.

The airline said the complaints only represent one percent of the 70,000 employees wearing the new uniforms, Fortune reports.

The airlines is still looking into the matter and said the uniforms were tested twice before being distributed.

The company said employees can choose to wear the old uniform if the new one is making them sick.