U.S. health regulators acknowledged they miscalculated the amount of formaldehyde emitted from some of Lumber Liquidators' laminated floor products. Shares of the company fell sharply Monday on the news.

The Centers for Disease Control And Prevention says the risk of cancer is three times higher than it previously estimated, and it strongly urged Lumber Liquidators customers to take steps to reduce exposure to the substance. The company no longer sells the Chinese-made, laminate products.

The agency said its "indoor air model used an incorrect value for ceiling height. As a result, the health risks were calculated using airborne concentration estimates about 3 times lower than they should have been."

The higher levels "could cause increased frequency of asthma symptoms and other respiratory issues for people with asthma and COPD [chronic obstructive pulmonary disease]."

Last March, a report on 60 Minutes said laminate floor products made in one of the retailer's Chinese factories had unsafe levels of formaldehyde, a known carcinogen. At the time, the company disputed the allegations, saying they were driven by short-sellers who stood to benefit when the stock price fell.

On Feb. 10, the CDC issued a report estimating that the risk of cancer presented by the products was two to nine cases per 100,000 people. The agency subsequently learned that the risk was six to 30 cases.

The error occurred because the CDC neglected to convert feet to meters in some calculations in the first reports, according to 60 Minutes.

The CDC said the acknowledgement of the error had not changed its fundamental recommendations to customers dealing with the contaminated products:

"Our recommendations will likely remain the same — we strongly stress taking steps to reduce exposures, which should alleviate respiratory and eye, nose and throat irritation. These steps should also reduce the cancer risk."

The company said it supports the recommendations and is "encouraged" that the agency is reviewing its calculations, according to Bloomberg News:

"The company also repeated that it has strengthened its quality-assurance procedures, suspended sales of Chinese laminate and offered free air tests to customers." 'We remain committed to operating with integrity and delivering quality flooring to our customers,' the Toano, Va.-based company said in an e-mailed statement."

Last year, the company pleaded guiltyto charges of making false declarations on import documents about the source of some of its flooring, and it agreed to a multimillion-dollar settlement with the Justice Department.

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