Centers for Disease Control and Prevention Considering Lowering Lead Exposure Threshold Level
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Centers for Disease Control and Prevention Considering Lowering Lead Exposure Threshold Level

The change may help healthcare professionals identify more children affected by the toxic metal

December 30, 2016

The U.S. Centers for Disease Control and Prevention (CDC) may soon lower its threshold for high levels of lead in children's blood by 30 percent.

The move may help healthcare professionals to find more children who are being affected by the toxic metal, says Reuters.

The CDC is in charge of setting standards for exposure to lead for the public health. Since 2012, it has been using a threshold level of five micrograms per deciliter of blood for children under the age of six. Although there is no level of exposure to lead that is safe for children, says the agency, those children who test at or above that level justify a public health response.

The CDC is thinking about lowering its reference level to 3.5 micrograms per deciliter based on new data collected in a national health survey. It plans to discuss the change at an upcoming agency meeting on January 17 in Atlanta.

However, the step, which the CDC has been considering for months, may not be approved by everyone. One concern is that it may take away resources from the children who need the most help, those whose lead levels are much higher. These resources are already stretched thin.

Being exposed to lead, which usually happens from old, peeling paint, tainted water, or contaminated soil, can cause mental damage and other health problems that cannot be reversed.

The CDC changes its threshold level periodically as the average levels of lead across the country drop. The threshold value is meant to identify the children whose blood levels place them in the 2.5 percent of children who have been exposed the most.

Bernard M.Y. Cheung is a University of Hong Kong professor who studies lead data. "Lead has no biological function in the body, and so the less there is of it in the body the better," he says. "The revision in the blood lead reference level is to push local governments to tighten the regulations on lead in the environment."

The agency is talking with state health officials, laboratory operators, medical device makers, and public housing authorities about how and when to put a new threshold into practice.

The average blood lead levels in children have dropped by more than 90 percent since the metal was banned from paint and phased out of gasoline almost 40 years ago. The average amount now is roughly one microgram per deciliter.

However, progress has not been equal across the country, and lead poisoning is still an urgent and dangerous problem in many communities.

Reuters recent found almost 3,000 places with recently-measured rates of lead poisoning of at least 10 percent, which is two times higher than the rates measured in Flint, MI, during that city's crisis over lead in water. More than 1,100 of the communities whose rates were measured by Reuters had a rate of raised blood tests at least four times higher than those in Flint.

In the urban areas that were affected the most, as many as 50 percent of the children recently tested had higher levels of the metal in their blood.

As many as 500,000 children in the U.S. , estimates the agency, have levels of lead in their blood that are either at or above the current threshold. For these children, it encourages "case management," which is often done by either state or local health departments and can include teaching families about lead safety and ordering more blood tests, home inspections, or remediation to be done.

There are also financial implications to any change in the CDC's threshold level. Its budget for helping states with their lead safety programs in 2016 was only $17 million. In addition, many state or local health departments do not have enough employees to treat those children who test high for lead levels.

Another concern is that several devices and labs that test for lead currently have trouble identifying levels in the three micrograms per deciliter range. There can be margins of error in the test results.

"You could get false positives and false negatives," said Rad Cunningham, an epidemiologist with the Washington State Department of Health. "It's just not very sensitive in that range."

The CDC has no power to regulate, which means that states are left to make their own decisions about how to proceed on public safety matters. Several states have still not adapted their programs for preventing lead poisoning to the last threshold change, which was made four years ago when the level dropped from 10 micrograms to five. Others, like Virginia and Maine, made changes this year.

The U.S. Department of Housing and Urban Development (HUD) may soon adopt a rule requiring an inspection of the environment, and cleanup of any lead if hazards are found, for any public housing units at which a young child's blood tests show a lead level at or above the CDC's threshold.

HUD says that it will take public health action under a new threshold if urged by the CDC.

"The only thing that will affect our policy is the CDC recommendation for environmental intervention," said Dr. Warren Friedman at HUD's Office of Lead Hazard Control and Healthy Homes.