The Department of Labor’s Occupational Safety and Health Administration officially opened an investigation Tuesday into auto supplier Renosol.

OSHA spokesperson Lindsay Williams confirmed the start of an investigation Tuesday in an email.

The investigation is based partly on a list of employee complaints and follows an internal investigation by Renosol’s parent company, Lear Corporation. Lear plans to announce results of its internal investigation on Wednesday.

Lear’s Vice President of Environmental Health and Safety Barbara Boroughf said the company was notified of the investigation at approximately 9 a.m. Tuesday when an OSHA safety engineer arrived at Renosol’s Craig Field plant.

The investigation is also based on an OSHA regional emphasis program for safety hazards in the auto-making industry.

“It’s not unusual for OSHA to come to manufacturing sites,” Boroughf said. “Our Montgomery plant was visited as a result of that program, and we received no citations.”

OSHA’s plant inspections include researching the site’s previous history, conducting a walkthrough of the facility and inspecting for hazards that could lead to injury or illness, according to OSHA documents.

If issues are found, OSHA must issue a citation and proposed penalty within six months, according to agency documents. Violations are categorized as other-than serious, serious, willful, repeated and failure to abate. Penalties could be $7,000 for each serious violation and $70,000 for each willful or repeated violation.

If any citations are found, Lear will be offered an opportunity to discuss findings with OSHA.

Complaints were made public after employees delivered a list of grievances to Renosol’s human resource manager on May 8.

The letter specifically addresses excessive employee exposure to a chemical called Toluene disocyanate, also known as TDI. Employees said exposure to the chemical causes asthma-like symptoms in employees.

A news release from a public relations firm representing the employees stated 75 percent of the roughly 90 workers at the plant suffer from some type of respiratory illness associated with TDI.

TDI is toxic for both short- and long-term exposure, according to the Environmental Protection Agency. According to the EPA website, chronic inhalation of TDI can result in significant decreases in lung function and asthma-like reactions.

OSHA’s records don’t show any previous investigations of Renosol’s Dallas County plant since January 2011. OSHA was established under the U.S. Department of Labor by an act of Congress in 1970.