In its latest , Apple said of the exposed workers "we continue to monitor their medical reports until full recuperation." The report added, "A majority of the 137 workers have returned to employment at the same factory."

But both Guo and Jia, the two workers at the factory, say their symptoms are returning and have been asking Wintek to provide further medical treatment. So far, the supplier has given them no clear response.

"The company says if you feel like the symptoms are returning it's because of your own personal reasons," Jia said. "They said it's because you have been drinking, or smoking."

Jia says he neither drinks or smokes.

The employees say Wintek has offered them compensation, but at the cost of leaving their jobs and signing an agreement that says they will no longer have ties to the company.