A national report released Tuesday says dangerous levels of a chemical that could cause cancer is contaminating the tap water for hundreds of millions of Americans, according to a CNN article.

The chemical, chromium-6, was featured in the popular movie "Erin Brokovich."

The study was done by Environmental Working Group (EWG).

In the report done by EWG, an interactive map shows which counties were tested and if they tested positive for chromium-6.

Counties in our area that tested positive for chromium-6 include Kanawha, Cabell, Putnam, Mason, Logan, Mingo and Fayette in West Virginia.

In Ohio, counties include Lawrence, Scioto, Gallia and Meigs.

In Kentucky, counties include Boyd, Carter, Johnson, Pike, Martin and Floyd.

According to CNN, chromium-6 is produced by industrial processes, as well as being found in the ash from coal-burning power plants and is used to lower the temperature of water in the cooling towers of power plants.

The U.S. Occupational Safety and Health Administration sets strict limits for airborne chromium-6 in the workplace.

The Environment Protection Agency has not set a specific limit for chromium-6 in drinking water, CNN says.