(Reuters) - The U.S. health regulator on Thursday raised concerns about Meridian Bioscience Inc’s facility that manufactures lead testing devices, nearly two months after the regulator warned that the tests may underestimate lead levels in blood.

The Food and Drug Administration said it had issued Meridian unit, Magellan Diagnostics, a Form 483 for its North Billerica, Massachusetts-based facility, which manufactures the devices.

Magellan’s devices are the only lead testing products cleared by the FDA and account for about half of all lead tests in the United States.

If the agency finds problems in company facilities, it issues a Form 483 — a notice outlining violations — which if not resolved can lead to a "warning letter" and in worst case, a ban. (bit.ly/2udKvM8)

In its report, the FDA listed certain observations that may be in violation of federal law, including concerns that design validation studies on some devices did not ensure they work the way they are intended to.

The agency also called out the company for failing to identify potential risk to patients from a falsely low test result.

"We are carefully reviewing the evidence collected during the inspection to determine if there have been violations of federal law and whether further action is warranted," the FDA said in a statement on Thursday. (bit.ly/2tMXFP1)

Meridian said its unit will respond to the issues raised by the agency.

“Magellan is addressing the observations noted in the Form FDA-483 with the highest sense of urgency,” the company said in a statement on Thursday.

In May, the FDA warned laboratories and healthcare professionals not to use any lead testing device made by Magellan, which was bought by Meridian in 2016, to test blood drawn from veins.

The tests are designed to detect lead poisoning that can stunt children’s growth and reduce IQs, according to the Centers for Disease Control and Prevention.

Awareness of lead poisoning escalated following widespread exposure in Flint, Michigan. Reuters has identified more than 3,300 areas with lead poisoning rates in children at least double those found in Michigan City.