Lumber Liquidators Holdings Inc. flooring, tested for formaldehyde, was found to have a three times higher risk of causing cancer than previously stated, U.S. regulators said in reversing their own finding from earlier this month.

A report released Feb. 10 used incorrect ceiling heights, lowering by about three times the airborne concentration that should have been examined and reducing the danger, the U.S. Centers for Disease Control and Prevention said in a statement on its website.

The estimated risk of tumors is six cases to 30 cases per 100,000 people, the CDC said, above the two to nine cases in the earlier report.

The company has three stores in Maine, in Brewer, Scarborough and Auburn, according to its website.

Lumber Liquidators tumbled 19 percent to $11.51 at 7:13 a.m. in early trading in New York on Monday. The shares already had plummeted more than 70 percent since the March airing of a “60 Minutes” story that alleged Lumber Liquidators flooring had potentially dangerous levels of formaldehyde.

The crux of the allegations was that Lumber Liquidators sold laminate flooring with levels of formaldehyde above regulations in California, which has the strictest standards in the country. After the “60 Minutes” story, the company raised doubts about the testing that the show had used, saying it wasn’t measuring the amount of formaldehyde that may be released in a person’s home.

Lumber Liquidators didn’t immediately return a phone message or email left outside regular business hours.

Formaldehyde is a naturally occurring colorless, flammable chemical used to make certain building materials and household products that is toxic to animals, including humans. People with breathing conditions including asthma and bronchitis are especially sensitive to formaldehyde exposure.