Screening

Michael Weitzman, MD, on How Pediatricians Should Screen for Lead Exposure

In April 2019, the US Preventive Services Task Force (USPSTF) updated its 2006 recommendation statement on blood lead screening in children and pregnant women. The Task Force changed its stance on screening, stating that there is insufficient evidence to assess the benefits and harms of screening after initially recommending against screening in 2006.1

Notably, the USPSTF also found adequate evidence that capillary blood testing can accurately identify children and pregnant women with elevated blood lead levels, but that questionnaires and other clinical prediction tools used to identify asymptomatic children and pregnant women are likely inaccurate.1

Of course, this raises questions as to what pediatricians and other providers should do in the interim, now that the efficacy of screening remains unknown, and commonly used prediction tools such as questionnaires are likely ineffective on an aggregate level.

Consultant360 spoke with Michael Weitzman, MD, professor in the Department of Pediatrics at New York University School of Medicine, who wrote an accompanying editorial for the new recommendation statement, which was published in JAMA Pediatrics.2 Dr Weitzman shed light on some unanswered questions about blood lead screening that have emerged in the wake of the USPSTF’s updated recommendation statement.

Consultant360: In your view, what is the important takeaway of the USPSTF’s recommendation statement on blood lead screening in pediatric patients?

Dr Weitzman: I think an important point to remember is that the USPSTF determined that evidence regarding the benefits and harms of lead screening is inconclusive. Unlike their 2006 statement, they did not suggest that blood lead screening should not be performed, but that current data is not sufficient to be able to offer an opinion one way or another on the efficacy of screening. Half a million children in the United States have elevated blood lead levels, and it is known that the health impacts of elevated blood lead levels are major in many cases. We know that this is a very serious issue, and although we are currently not sure if the current interventions we use will really help prevent further elevations or enhance decreases in children’s blood lead levels, this does not mean that we should discontinue screening.

C360: Despite progress, lead exposure remains a serious problem in the United States, and there seems to be a disconnect between what we know about the health consequences of lead poisoning and our current ability to reach children affected by it. How can current knowledge inform future endeavors to prevent lead exposure in children?

Dr Weitzman: Anyone who cares for children must recognize that lead exposure in the United States is a manmade epidemic that has not yet ended. Over the past several decades, lead levels in the blood have decreased drastically among kids in the United States. In 1970, the mean blood lead level of kids in the United States was about 16 μg/dL. Now, it is about 1 μg/dL. This is a consequence of multiple federal actions, legislation, and regulations – such as the deleading of gasoline and household paint in the 1970s – that have been profoundly successful.

On the other hand, although we have succeeded in this regard, there has been an enormous research literature since 2005 that shows that there is no safe level of lead in the blood and that even the lowest measurable levels can cause harm. We also know that there is a dose-effect response. Increasingly higher blood lead levels are associated with higher likelihood of lost IQ points, attention-deficit hyperactivity disorder, behavior problems, school failure, and social difficulties, with some data showing that higher blood lead levels may be tied to violent behavior. In the United States, children under age 5 years have the greatest risk, and as I said earlier, there are half a million of these children still at-risk.

A problem we are currently facing is that most of the studies related to preventing and treating elevated blood lead levels were performed 10 to 20 years ago or longer, when blood lead levels were much higher. These studies have to be replicated, but it is challenging to perform such studies. In forming recommendations, the USPSTF looks almost exclusively at randomized controlled trials, which are very difficult to perform in this context. We cannot intentionally expose a child to lead, and it would be difficult to randomize a child to different types of treatment. So, the USPSTF’s latest recommendation statement really argues for a lot of research, and in the interim, leaves decision-making regarding screening up to individual organizations or individual physicians.

Right now, lead screening uses a model that involves looking for children with elevated blood lead levels in order to identify “sick” homes. However, I find that this process is backwards because it identifies children that have already been exposed rather than preventing exposure in the first place. To prevent lead exposure, we could use geospatial epidemiology to identify communities with the oldest houses that are most likely to be in disrepair and where the highest percentage of kids in the past have had elevated lead levels. Most exposure comes from lead-based paint that is chipping, peeling, and flaking. Furthermore, the Flint water crisis in Michigan has made us aware that we have a fraying water infrastructure, and now we have to work to lower lead levels in water.

C360: In your view, what should pediatricians do in this interim period? How can pediatricians reach children who have potentially been exposed to lead?

Dr Weitzman: A really interesting question at this point in time is, how does one go about determining whether a child is at risk or not? Knowing that the USPSTF says blood lead screening questionnaires are not effective, what is the guidance for a practitioner going forward? If you do not screen a child or at least ask questions of parents, you could potentially miss a child who is going to sustain serious damage from lead exposure. We need some way of estimating whether or not a child and/or other family members should be screened.

Until further notice, I would follow the guidance of the American Academy of Pediatrics (AAP), Centers for Disease Control and Prevention (CDC), and/or state health departments.3,4 The AAP recommends screening every child at 1 to 2 years of age, using a questionnaire, or following local or state regulations.3 The CDC suggests using a questionnaire to screen for blood lead exposure.4

In the past, I have created and studied surveys or questionnaires that do not work in the aggregate, but do contain the kinds of questions one needs to ask to identify high-risk kids. Key questions pediatricians can ask parents of at-risk children include:

  • Whether they live in a house built before 1970, or especially before 1950. In 1978, a regulation was passed prohibiting the use of lead-based paint in homes. However, a substantial number of homes built before 1950 have lead-based paint in disrepair.
  • The professions or occupations of parents – whether they work in lead smelters, construction, demolition, or with ceramics or car batteries, all of which are tied to elevated lead exposure. Parents should also be asked whether their children live near lead smelters.
  • Whether the children are immigrants or adoptees from abroad. Many countries, including various Central and South American countries, have ceramics that are glazed with lead-based paint.
     

Any children with any of the above factors should be screened, and any child whose parent expresses concern about lead exposure should be screened.

—Christina Vogt

References:

  1. USPSTF. Screening for elevated blood lead levels in children and pregnant women. JAMA. 2019;321(15):1502-1509. doi:10.1001/jama.2019.2594.
  2. Weitzman M. Blood lead screening and the ongoing challenge of preventing children’s exposure to lead [Published online April 16, 2019]. JAMA Pediatr. doi:10.1001/jamapediatrics.2019.0855.
  3. American Academy. of Pediatrics Committee on Environmental Health. Screening for elevated blood lead levels. Pediatrics. 1998;101(6):1072-1078. https://pediatrics.aappublications.org/content/pediatrics/101/6/1072.full.pdf.
  4. Advisory Committee on Childhood Lead Poisoning Prevention. Centers for Disease Control and Prevention. Low level lead exposure harms children: A renewed call for primary prevention. https://www.cdc.gov/nceh/lead/acclpp/final_document_030712.pdf. Published in 2012. Accessed on April 23, 2019.