An estimated 8,000 truck drivers who received their medical certifications from an Atlanta-based doctor are at risk of having their commercial driver’s licenses suspended unless they retake their medical exams within 30 days of receiving notice.

Earlier this month, Dr. Anthony Lefteris was busted by federal officials for handing out passing medical results to his patients without performing the required tests. Lefteris was a FMCSA-certified medical examiner who operated out of the Petro truck stop located at 3181 Hollowell Parkway in Atlanta, Georgia.

An investigation into Lefteris’s shady business practices began back in September after several drivers reported his inadequate testing procedures. During the investigation, three undercover officers received passing medical certifications from Lefteris without taking hearing or vision tests, or receiving a urinalysis.

As a result, up to 8,000 drivers will have their medical cards invalidated. Affected drivers will be notified by mail and have 30-days from the posted date to receive a new medical certification from an FMCSA certified medical examiner.

“Drivers that fail to obtain medical requalification within the 30-day time period will be medically disqualified from operating,” said FMCSA spokesperson Duane DeBruyne.

According to AJC.com, Lefteris was conducting an average of 360 medical exams a month, while the typical medical examiner completes only about 14.

The 71-year-old doctor was arrested on December 1st and charged for submitting false information to a federal agency.