Home Depot Inc. will pay a $20.8 million fine for failing to ensure that its contractors follow lead paint rules. The civil penalty announced Thursday by the Environmental Protection Agency is the largest such penalty to date under the Toxic Substances Control Act.

Under the proposed settlement, Home Depot must implement a program to ensure that the firms and contractors it hires to perform home renovations are certified to use lead-safe work practices.

The Atlanta company announced in 2017 that it was the subject of a probe by the EPA's criminal investigation division into its compliance with lead-safe work practices. Home Depot then said it was cooperating with the EPA.

EPA said that while investigating customer complaints about Home Depot renovations, it found the company subcontracted work to firms that did not use lead-safe work practices. It also did not perform required post-renovation cleaning, give EPA pamphlets on lead-based pain to occupants, or maintain records of compliance with the law, the agency said.

Residential lead-based paint was banned in 1978 but still remains in many older dwellings. Exposure to lead dust and paint chips can cause health problems including behavioral disorders, learning disabilities, seizures and even death.

The U.S. is joined by three states. Of the $20.75 million penalty, Utah will be paid $750,000, Massachusetts will be paid $732,000 and Rhode Island gets $50,000.

The proposed settlement, lodged in the U.S. District Court for the Northern District of Georgia, is subject to a 30-day public comment period and final court approval.