(AP) – Federal investigators who visited a Mars plant near Joplin found potential dangers to the health of employees but the company closed the plant before a follow-up visit could be arranged.

Eight former workers at the plant sued Mars last year, alleging they were exposed to a fumigant that caused them to become ill.

Investigators with the National Institute for Occupational Safety and Health visited the plant in December 2012, at the request of some employees. The team found evidence of dust, high mold samples and the potential for release of diacetyl, which has been linked to a lung disease.

A spokeswoman for Mars Petcare says the decision to close the plant in June 2013 was driven by the economy, not by the health report.