The lessons of lead: Early advocacy on environmental health

By Dr. Robin Walker

“Lead has no known benefits to health and it would seem not only reasonable, but highly desirable to reduce the risks of lead exposure as far as possible”. This quote forms part of the conclusions of a CPS statement from 1986, authored by Dr. Peter Rosenbaum, titled “Lead Poisoning – Menace or Myth? An Updated Review of Evidence”. The statement noted that while lead poisoning had been recognized as a serious disease for a very long time, uncertainty still remained about the impact of “subclinical” lead burden in children, particularly in terms of brain function and development ^[1]. After an extensive review of evidence available at that time, Rosenbaum concluded that precautionary measures such as environmental manipulation and long-term surveillance were appropriate, particularly for children at increased risk of lead exposure, even though a full understanding of the impacts of elevated body lead levels on the health and development of children was not yet possible.

CPS statements have been a mainstay of clinical advice for Canadian paediatricians and others working to improve the health of children since the Society was founded 100 years ago. Even so, it may surprise some that 35 years ago we were already producing highly evidence-based statements advocating for change in areas of clinical and environmental controversy. The approach to statement production may have been less rigorous than it is now (see “About CPS Position Statements”), but  evidence use and the conclusions thus derived were well established, and the application of that evidence to a need for change to protect the health and well-being of children was clearly stated.

In 1999, Woolf et al ^[2] suggested that while clinical practice guidelines had many benefits, they could also cause harm when the recommendations were not based on evidence or evidence was inadequate or misinterpreted. Kredo ^[3] noted that by 2016, clinical practice guidelines had indeed shifted from opinion-based to evidence-informed. The CPS statement of 1986 demonstrates that the CPS made that shift much earlier.

Evidence for the impacts of low levels of lead on child health, particularly development, has gradually accumulated since. Notwithstanding the recommendation for surveillance in the 1986 CPS statement, Tsekrekos and Buka observed in Paediatrics & Child Health in 2005 that surveillance of blood lead levels in Canadian children remained limited ^[4]. However, they noted that harmful health effects of low-level lead exposure were now recognized by the U.S. Centers for Disease Control and might occur below the established standards for lead levels. They suggested that Canadian regulations seemed inadequate to protect children and were in need of revision. The Council on Environmental Health of the American Academy of Pediatrics provided updated guidance on preventing lead toxicity in 2018 ^[5]. They observed that while blood lead concentrations in American children had decreased dramatically over the previous 40 years, many children still lived in situations placing them at risk for lead exposure. They reviewed evidence that low blood lead levels, even commonly encountered levels below 5 µg/dL, impair cognition, and concluded there is no identified safe level of lead in blood.

A 2019 CPS practice point written by Buka and Hervouet-Zeiber reiterated the link between low lead levels and neurodevelopmental deficits. They reinforced the need for “early detection and prevention of lead exposure as key public health objectives, because effects of lead toxicity are chronic and treatment is complex”. We can now decisively answer Rosenbaum’s question in 1986: Lead poisoning, even at low levels, is indeed a menace, not a myth.

Comparing present-day statements with the past, it is evident that speaking to levels of evidence and providing strength of recommendations reinforce the credibility of current CPS statements, but these practices were not in use in 1986. The earlier statement correctly asserts that evidence available at that time did not point conclusively to the harmful effects of low-level lead exposure. The recommendations for surveillance, detection, intervention, and prevention served both to build understanding of the problem’s scope and increase protection of children as that understanding was developing. Today’s new paediatricians should be impressed at the power of evidence-based education and advocacy even 35 years ago!

Finally, the progress of knowledge on lead exposure reminds us of many current issues where we lack a full understanding of impact on child health. Children are exposed to many potential toxins as they grow: Which will prove to be most harmful when we have longer-term evidence? Will it be cannabis, or the products of vaping? Maybe childhood exposure to certain pesticides will prove to have caused significant harm to long-term health. For sure we will have a much greater understanding of how climate change has impacted the health of today’s children. Yet in the face of such uncertainties, the 1986 statement reminds us that while we should always “follow the evidence” once it exists, there are times when we can advocate for changes to protect children’s health as we work to discover stronger evidence for greater certainty. CPS statements continue to interpret evidence so clinicians can best use it, but they also encourage us to work for clearer evidence and better child and youth health at the same time.

Dr. Robin Walker is a past president of the CPS and a professor of paediatrics at the Schulich School of Medicine and Dentistry, Western University. He chaired the CPS Paediatric Environmental Section for many years, and remains an active advocate for the rights and health needs of children and youth.  

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