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People exposed to certain types of laminate flooring made by Lumber Liquidators are three times more likely to get cancer than previous estimates had suggested, U.S. health officials say.

The Centers for Disease Control and Prevention (CDC) said last week that the flooring, which was tested for formaldehyde, was found to have a three times higher risk of causing cancer than previously stated. This revises the CDC’s own findings from earlier this month.

On February 10, the CDC released a report that said exposure to the flooring posed a “low risk of cancer.” The agency has now updated that statement saying the report used incorrect ceiling heights. As a result, the health risks were calculated using airborne concentration estimates about three times lower than they should have been.

“Health risks of people who have the laminate flooring are being revised to reflect greater exposure to formaldehyde, which could cause eye, nose, and throat irritation for anyone. The estimated risk of cancer associated with exposure to the flooring increased,” the report said.

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The agency says select versions of the company's laminate flooring could cause 6-30 cancer cases per 100,000 people, compared to the 2-9 cases it had originally estimated in its February 10 report.

"Because of the very conservative (health protective) nature of the models used in this analysis, ‎the calculated risk is likely lower than our modeled estimate," the CDC said.

Related: Feds Confirm Investigation Into Lumber Liquidators Flooring

The CDC says exposure to the revised formaldehyde levels in indoor air could cause increased symptoms and other respiratory issues for people with asthma and chronic obstructive pulmonary disease. Exposure to the lowest modeled levels of formaldehyde could result in eye, nose, and throat irritation for anyone, the agency added.

“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 news has shaken up investors, sending Lumber Liquidators stock down 17 percent to $11.83 in pre-market trading. They had been mildly encouraged by the CDC’s February 10 report.

The company's' shares and sales have been in a tailspin since March last year when CBS "60 Minutes" reported the retailer's laminates from China contained excessive levels of formaldehyde.

A few months after that report aired, the company halted the sale of all Chinese-made flooring and the CEO resigned.

"Despite the errors in CDC's calculation, we note that they do not expect to change their recommendations and we support those recommendations,” Lumber Liquidators said in a statement to NBC News on Monday.

“Since March of 2015, Lumber Liquidators has offered customers free independent air quality tests to provide objective scientific information about our products. We remain committed to operating with integrity and delivering quality flooring to our customers."