They added that women who are pregnant or breastfeeding should get retested too, while other adults concerned about lead exposure should talk to their doctors about a possible repeat test.
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. Now available data indicate that the lead tests, when performed on blood drawn from a vein, could provide results that are lower than the true level of lead in the blood.
The problem with the venous blood testing appears to date back to August 2014 when Magellan received a number of complaints from customers about its LeadCare Ultra device, the FDA said. The lead poisoning tests are made by Magellan Diagnostics. The warning only applies to tests in which blood samples were taken from a vein, not for the more common tests in which fingers or heels are pricked for a blood sample.
Neither are there problems with other blood tests used to detect lead, which account for about half the total, he said. Lead is particularly unsafe for infants and young children.
The agency also urged women who are now pregnant or nursing and were tested in this manner, to get retested.
In an email to MLive-The Flint Journal, Genesee County Health Department Health Officer Mark Valacak said officials received information on the blood testing issue during a conference call Wednesday.
Shuren said that since the beginning of 2014, they estimate that 8 million tests were used with the Magellan system, but "the majority were for capillary blood".
Doctors say pregnant and nursing women, as well as kids under the age of 6 should ask their doctors if they should be retested. Those kinds of blood draws are usually done in labs.
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.
The CDC's threshold for elevated lead is 5 micrograms per deciliter of blood.
Lead exposure shows no obvious symptoms and often goes unnoticed, which can lead to serious adverse events.
"There is no safe level of lead exposure for children, and the best "treatment" for lead poisoning is to prevent lead exposure before it happens", said Jennifer Lowry, chair of the American Academy of Pediatrics Council on Environmental Health, according to The Washington Post. "The AAP will work with our pediatrician members to provide those families impacted by today's warning with the resources and guidance they need to protect their children from lead exposure", said Fernando Stein, MD, FAAP, president of the AAP.