The FDA and the company said they are working to determine the cause of the inaccurate results. Food and Drug Administration and the Centers for Disease Control and Prevention issued a warning that certain lead tests manufactured by Magellan Diagnostics may provide inaccurate results.
Lead poisoning is hard to detect, but exposure to even small amounts of lead can result in serious health issues for children, who are at risk of developing "irreversible" brain damage and seizures, according to the Mayo Clinic.
"The FDA is deeply concerned by this situation and is warning laboratories and health care professionals that they should not use any Magellan Diagnostics lead tests with blood drawn from a vein", said Dr. Jeffrey Shuren, director of the FDA's Center for Devices and Radiological Health.
MDHHS said in a news release Wednesday that less than 2 percent of lead tests performed in MI since 2014 - including 128 in Flint - were done using Magellan equipment that processed blood drawn from veins. It is the venous tests, if run on Magellan LeadCare Testing Systems, that are of concern.
But earlier this year, when FDA officials became aware of the problem, Shuren says the agency believed that the company had underestimated the risk to the public, and that the data supporting the mitigation plan wasn't sufficient. Finger-prick tests are exempt for now. The recommendations do not apply to tests taken from a finger or heel stick.
The FDA and CDC are now "aggressively investigating" the issue with inspectors on site at Magellan and the two agencies conducting testing of all of Magellan lead testing products, Shuren said. The institutions noted that the problem could go as far back as 2014.More news: Trump doesn't plan to use Israel trip to announce embassy move
The CDC recommends that parents of children who were under the age of six, women who were pregnant, and mothers who were nursing at the time they were tested should ask their doctor if they should be retested.
It also recommended that women, who are now pregnant or nursing and were tested in this manner while pregnant or nursing, get retested. She said the company's Ultra and Plus systems, launched in 2013 and 2015 respectively, are typically used to analyze venous blood, though they can analyze capillary blood as well.
"No safe blood lead level in children has been identified".
Since a year ago, Reuters has identified more than 3,300 US neighborhood areas with documented childhood lead poisoning rates double those found in Flint, Michigan.
"There may be differences in how the blood is collected, the tubes that may be used for it, or some of the other processing, and that may account for why there are differences", he said. If such results find elevated lead levels, the results are confirmed through a venous blood test.
The FDA, an agency within the U.S. Department of Health and Human Services, promotes and protects the public health by, among other things, assuring the safety, effectiveness, and security of human and veterinary drugs, vaccines and other biological products for human use, and medical devices.