Issues in pediatric blood lead testing

April 08, 2022

6 min read

Source/Disclosures

Disclosures:
Woolf reports no relevant financial disclosures. Brown reports being a technical advisor for Magellan Scientific.

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A recent CDC revision to the reference value used to identify children with high levels of lead in their blood doubled the estimated number of children who should be referred for follow-up, per guidelines, a pair of experts noted recently.

In a perspective published in Pediatrics, Alan D. Woolf, MD, MPH, director of the environmental medicine program at Boston Children’s Hospital, and Mary Jean Brown, ScD, RN, former chief of the CDC’s Lead Poisoning Prevention Branch, also discussed the reissue of the LeadCare II testing instrument following a recall.

We spoke with Woolf about blood lead testing in children.

Alan D. Woolf

Healio: What does the CDC’s reference value (RV) for a child’s blood lead level (BLL) mean?

Woolf: The CDC calculates RV based on the National Health and Nutrition Examination Survey, which measures various chemicals, including lead, in blood samples taken from kids across the United States. The CDC then takes that data and calculates the upper 97.5th percentile of the population. That’s the number that they call the “reference number” as the upper limit of an “acceptable” lead level.

So, it isn’t really a health-based number; it’s a population-based number. Whatever the lead level is in the blood of the population, that reference number is specifically at the 97.5th percentile.

This is the first time the CDC has revised the reference level since 2012, when it was lowered to 5 mcg/dL. And, again, it points to the fact that the BLL has gone down in the population of preschoolers over those past 9 years, so that just last October the CDC lowered the RV to 3.5 mcg/dL. An RV lets you know where the child stands with respect to the population of preschool children nationwide.

Healio: What are the consequences of the pandemic on monitoring the lead exposure status of children?

Woolf: We don’t have the same insights into children and their families who may have a health issue related to lead contamination because the blood of some preschool children wasn’t tested for lead. The pandemic shut down well child checkups for a while in 2020, and it’s a fact that low body burden lead poisoning is often asymptomatic. A child may sometimes have a little constipation or irritability or poor appetite, but often they simply have no signs of lead exposure. That’s why we have screening in all 50 states, and then blood lead testing for those children felt to be at high risk. Screening children varies from state to state, in terms of the criteria used to determine when to get a blood test on a child. But the fact is, for high-risk children, if we don’t do the blood test, we may not know whether the child has been exposed to lead, either at home or in daycare.

It really has serious implications when, during the pandemic, people went into lockdown. People were afraid to go to the doctor. Many doctors closed their practices for a short time in 2020 while they adjusted their services. And when well childcare isn’t happening, lead testing of children is not happening.

As we noted in the article, across America, there was as much as a 34% reduction in the number of kids being tested for lead. Health care providers eventually were able to pivot and make the needed changes in their everyday practice to ensure the safety of their patients. And they have been trying to catch up with testing kids for lead since then.

Healio: What happened with the LeadCare II blood lead measuring instrument?

Woolf: That was a technical issue with the accuracy of that test, which first came to light, I believe, in 2021. The company reacted quickly to recall the lot numbers of test kits that were affected. Under the guidance of the FDA, the use of the LeadCare II instrument was paused in 2021 until they could clear up these technical issues.

So, pediatric practices, already stressed in delivering care during the pandemic now had to pivot and find another way to test children for lead. That meant having the child go to a hospital laboratory or commercial laboratory to get their blood drawn, rather than testing in the office itself. That change added a burden on the pediatric practices as well as on the families. For some of those labs, families had to make separate appointments. Sometimes the testing wasn’t convenient, and in some cases, it didn’t get done. Laboratory results had to be sent back to the doctor’s office and entered into the child’s medical record. Sometimes that might not happen correctly.

Those difficulties compounded the problems that we were already having getting kids tested because of the effects of the COVID-19 pandemic. Fortunately, the company resolved the technical issues, and with the approval of the FDA, LeadCare II kits went back into production for distribution in February 2022.

Healio: What should clinicians be doing to help families of kids with elevated BLLs?

Woolf: Pediatric health care providers are using the new RV of 3.5 mcg/dL to identify children at high risk of continuing exposure to the metal. In the article, we urge clinicians to continue to test children to see if they have an elevated lead level. If children have an elevated level, then this is a wonderful opportunity to counsel families. We made some points in the commentary of things that pediatric health care providers have been doing all along and should continue to do. For example, they can counsel families about dietary intake of calcium, iron, vitamin D and other essential minerals and vitamins in foods. Those can help in a child who has an elevated lead level and may be iron deficient. And they should continue to monitor the child’s blood periodically until the lead level falls below the RV.

Healio: What should families be doing at home?

Woolf: Families living in older apartments or homes built before 1978, and especially those built prior to 1960, should get their home professionally inspected for lead contamination. And we recommend all sorts of attention to the home environment. Some of the things we suggest, interestingly enough, are the same things we have been doing over the past 2 years for preventing COVID-19 infection, such as cleaning and disinfecting high-touch surfaces, including tabletops, baseboards, furniture and windowsills. Besides reducing the risk for COVID-19 infection, cleaning floors and high-touch surfaces is also effective for cutting down on lead-containing dust that kids can get exposed to by putting their fingers in their mouth. Dusting rooms, damp-mopping floors and cleaning high-touch surfaces with soap and water several times a week lowers the risk of lead contamination in older homes and apartments. Everybody should leave their shoes at the front door, so they don’t track in lead-containing dust or dirt from outside the home.

Careful and frequent handwashing is important. Just like we do for COVID-19, wash your hands for at least 20 seconds, and wash your toddler’s hands frequently. Toddlers put their fingers in their mouth, they explore toys by mouthing them, so by getting rid of dust and by careful, frequent handwashing, we are trying to break the hand-mouth cycle of lead dust ingestion. Same thing for cleaning plastic toys with simple soap and water, so they don’t accumulate dust.

Again, we’re just trying to interfere with that hand-to-mouth behavior that that puts kids at risk for getting lead from dust inside the home.

Healio: Are there other ways pediatric health care providers can help prevent childhood lead poisoning?

Woolf: What we also recommend for practitioners is that they advocate for policies and laws — local, statewide and federal — that will protect children and their families from lead.

Mary Jean Brown, who was my partner in writing this article, was the former head of the childhood lead prevention program at the CDC and has years of experience in public health. She mentions in the article the things that public health agencies can do. For example, when a town decides they have enough money to replace leaded water mains, they should make sure they replace all of the service lines so they will no longer be a source of contamination of drinking water.

Mitigating the lead hazard in housing is another important activity. Often homeowners and landlords have a hard time with lead abatement because of the economic cost. Attention to new legislative initiatives to “get the lead out” — regulations, resources, and funding made available to landlords and home-owners — as well as funding available to public housing authorities, will help make housing in the country hazard-free with respect to lead.

We want to make homes safe for children and give them a better environment in which to grow and flourish. It’s a big issue in our country.

Reference:

Woolf AD, et al. Pediatrics. 2022;doi:10.1542/peds.2021-055944.