Between Discovery and Invention

In 1981, a group of French pediatricians published a paper about a case of lead poisoning in the Archives Françaises de Pédiatrie. The clinical history of a five-year-old boy named Mammar was described in detail. He had been suffering from consciousness disorders and epileptic seizures, but all diagnostic investigations remained inconclusive. As his condition worsened, a neurosurgical operation was performed, with no success. Finally, from dozens of biological tests, some almost randomly selected, as often occurs in these difficult cases, one yielded an answer: a very high level of lead concentration was found in his blood.

The search for a diagnosis had been a lengthy process because, at that time in France, lead poisoning was considered a rare disease, mostly occupational, and afflicting adults. The pediatricians conducted a bibliographical inquiry and discovered that cases had been reported for decades in the United States involving children, generally living in underprivileged neighborhoods where white lead was used as house paint. Mammar’s parents confirmed that he sometimes put the flakes of old paint falling off the walls of their dilapidated flat in his mouth. The little boy was administered a chelator, i.e., a substance facilitating the elimination of lead from the blood, although not from the organs where it had accumulated, and as his condition apparently improved, he was sent home, where he probably continued inadvertently poisoning himself, if not by ingesting flakes, by inhaling the toxic dust. In their discussion of the case, the authors indicated that, contrary to what had been observed in North America, lead poisoning in children was “exceptional” in France: only ten cases had been recorded in twenty-five years.

In 1999, however, a report written by experts from the French National Institute for Health and Medical Research (INSERM) proposed quite a different picture: based on epidemiological studies conducted in France, an estimated 85,000 children were victims of lead poisoning, that is almost 2 percent of the age group; the disease was referred to as a “silent epidemic” and programs to combat it were declared a “national priority”; large-scale screening of low-income families living in aging housing was recommended and measures to renovate dwellings were proposed at a cost of approximately $5 billion.

Let us examine these two published accounts. In less than two decades, lead poisoning in children has evolved from an exceptional disease ignored by most pediatricians to an epidemic now regarded as a priority. Does this change reflect a massive propagation of lead in older housing? Has the proportion of children affected dramatically increased? Actually, it is exactly the opposite: the number of contaminated homes has diminished (many have been destroyed and white lead has not been used for half a century) and doctors hardly ever encounter children with high lead concentrations in their blood (severe cases such as Mammar’s have disappeared). So, how can we explain this evolution? It is not the biological reality that has changed, but the way it is viewed. Not so long ago, lead poisoning was a medical condition with hematological, digestive, and above all neurological disorders; individuals were diagnosed via X-rays and blood tests; they eventually received palliative drugs and were sent home. Now, lead poisoning is seen as an epidemiological fact analyzed in terms of prevalence rates and risk factors, as opposed to symptoms and signs; populations are screened on the basis of where they live rather than what they suffer from; prevention is preferred to treatment.

One way to interpret this change is to view it as the discovery of a fact that had been overlooked: children suffered from lead poisoning in the past but were not identified. This is actually part of the story. In 1985, a little girl was diagnosed with lead poisoning in a Paris hospital. Instead of routinely releasing her after she had received the palliative treatment, however, a social worker investigated her living conditions. Initially skeptical, local public health specialists were prodded to conduct a small study of the decaying building where she resided with other immigrant families in squalid conditions. They found high lead concentrations in the blood of several children and in the paint on the walls. Convinced by this unexpected evidence, they informed the public health department of a university of their findings and together they launched a screening program in facilities for mother and child health care. By 1990, 1,500 cases of lead poisoning in children had thus been diagnosed. The epidemic was born. Three factors had made this discovery possible. First, new actors were mobilized: public health specialists rather than clinicians, social workers as well as doctors, and subsequently town-planners and policymakers. Second, new tools were used: epidemiological studies and statistical analyses, prevalence rates and odds-ratios, instead of clinical examination, radiological explorations, and interviews with parents and inquiries into children’s behavior. Third, a new approach was formed: one of prevention rather than treatment, in which populations at risk were considered rather than individuals suffering from a disease. In sum, a new culture emerged, part of a larger picture in which public health as a mode of thinking and acting slowly—and belatedly––was developing in France, a country where the medical profession has long been disinclined toward social medicine. But the discovery of these previously undiagnosed children is not the sole explanation for the dramatic evolution of lead poisoning from an “exceptional disease” to a “silent epidemic.”

A second factor has to be taken into account: how lead poisoning in children was reinvented. When it was still a disease occasionally seen by pediatricians, i.e., when symptoms alone admitted young patients to the hospital, lead poisoning was defined by very high lead concentrations in the blood. In the early 1980s, medical literature often considered 35 or even 45 µg/dl as the pathological threshold: beyond it, one could see encephalopathy. But in fact, international epidemiological studies had identified adverse consequences at lower concentrations. The first investigation conducted in the Parisian building therefore used 25 µg/dl as its norm. The second survey subsequently carried out in the mother and child health care units considered 15 µg/dl as the acceptable limit. Finally, the INSERM report was based on concentrations above 10 µg/dl. Obviously, this decreasing threshold had the statistical effect of increasing the number of poisoned children. Public health specialists found many more cases but of a much less serious nature than medical doctors had previously. In so doing, the meaning of lead poisoning changed completely. It used to be a severe disease with neurological disorders sometimes leading to death (all cases had clinical symptoms). It was now evaluated in terms of an increased risk of developing learning disabilities (only some have significant difficulties at school).

What was once a pathology had become a probability. Recently epidemiologists even made lead responsible for children’s delinquency—again in a statistical sense, meaning that those with blood concentrations even slightly above 10 µg/dl were more likely to develop “antisocial behaviors.” In other words, the ten initially recorded patients suffered from a confirmed clinical condition, whereas the 85,000 estimated cases today correspond to a potential social condition. Thus, not only was lead poisoning in children discovered, it was reinvented. This is how the epidemic came into being. This story is not just about lead poisoning: it has important implications for our understanding of health problems. Too often we consider diseases as mere natural facts. When thinking this way, we elude the social work of actors who permanently redefine the boundary between “the normal and the pathological,” to paraphrase Georges Canguilhem. This concept is not only true of mental illnesses, for which it is well known, but also of somatic conditions: health problems are not pure biological entities; they are also complex social constructions.

Epilogue. In 1981, nobody took note of the fact that Mammar’s parents were Africans. Ten years later, however, as the epidemic swelled, it appeared that this characteristic was true of 99 percent of severe cases. Why would children diagnosed with lead poisoning be almost exclusively Africans? The initial answer was culturally based—doctors suspected traditional healing practices, the use of craft pottery, and women’s eye shadows. When it became clear that lead paint was the cause, they proposed a cultural form of geophagy, suggesting that African mothers had an idiosyncratic tolerance toward their children’s consumption of paint flakes. It took doctors years to admit this mundane reality: African families were part of the last waves of immigration, as borders started to close; during that same period, social projects became a scarce resource and these last immigrants, who also belonged to the lower classes, were housed in the most dilapidated buildings. This is how their children got lead poisoning. Instead of an exotic cultural explanation, one had to accept a political-economic interpretation, as the United States had acknowledged a few decades earlier, to account for the considerably higher prevalence of the disease in African-American neighborhoods. A final lesson that lead poisoning teaches us: health problems are not only socially construed, through statistics and studies; they are also socially produced, as the result of inequalities and policies.