Retraction Watch

Tracking retractions as a window into the scientific process

CDC fixes major error in flooring risk report: Not converting to metric

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CDCThe U.S. Centers for Disease Control and Prevention issued a correction notice to a report about formaldehyde in laminate flooring, saying a mistake had caused them to significantly underestimate the health risks.

The mistake: According to CBS’s 60 Minutes, the CDC sometimes didn’t convert feet to meters. Ouch.

In the corrected report, the agency estimates the health risks of the laminate flooring — by irritating the ear, nose and throat — to be three-fold higher than what they suggested in the original report, published February 10.

Here’s the note that now appears in the link to the original CDC report:

CDC/ATSDR was notified February 13 of an error in its report released February 10, 2016, about the possible health effects from exposure to formaldehyde emitted from select laminate flooring samples. 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 CDC/ATSDR 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 original report found:

-Exposure to the low end of the modeled levels of formaldehyde in indoor air could cause increased frequency of asthma symptoms and other respiratory issues for people with asthma and COPD;

-Exposure to the higher-end levels could result in eye, nose, and throat irritation for anyone; and

-Low risk of cancer (2-9 cases per 100,000 people).

After correcting the measurement in the model, CDC/ATSDR is revising the possible health effects. The final results are not yet available, but are estimated to be closer to these:

-Exposure to the range of modeled levels of formaldehyde in indoor air could cause increased symptoms and other respiratory issues for people with asthma and COPD;

-Exposure to the lowest modeled levels of formaldehyde could result in eye, nose, and throat irritation for anyone; and

-The estimated risk of cancer is 6-30 cases per 100,000 people. 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.

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.

When the report first appeared, stock prices for Lumber Liquidators — which sells the laminate flooring — increased. After the CDC issued its correction, however, prices fell significantly.

Questions over the health effects of the laminate flooring were raised after a 60 minutes report in March, 2015, which found:

Lumber Liquidators is a U.S. company, but much of its laminate flooring was made in China. And as we discovered when we first reported this story in March, it may fail to meet health and safety standards, because it contains high levels of formaldehyde, a known cancer-causing chemical. Lumber Liquidators has insisted ever since our report that its Chinese-made laminate flooring is safe, but it doesn’t appear that way based on what we learned from our own reporting and from the work of people like Denny Larson.

You can watch the entire report here.

60 Minutes is also the outlet that alerted the CDC to its mistake, says Bloomberg News:

The estimated risk of tumors is six cases to 30 cases per 100,000 people, more than the two to nine cases in the earlier report, said the CDC, which was notified about the error by “60 Minutes.”

In a statement to NBC News, Lumber Liquidators said:

Despite the errors in CDC’s calculation, we note that they do not expect to change their recommendations and we support those recommendations…

According to Lumber Liquidators, it now provides a free air quality test to some customers, to check levels of formaldehyde.

Here’s a link to the original (uncorrected) CDC report, published February 10.

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Written by Alison McCook

February 22nd, 2016 at 8:00 pm