LITMIR.BIZ

Скачать книгу

deficits similar to Sam’s: lowered IQ, behavioral disorders, perceptual problems, and other effects that seriously undermined the ability of children to succeed in school or work environments. This shift in focus—from the impact of relatively high blood lead levels as the cause of severe, sometimes fatal neurological damage to the subtler behavioral and intellectual deficits associated with low-dose lead exposure—raised new concerns about lead’s wide-ranging toxic effects and forced rethinking of what clinicians should attend to beyond textbook symptoms of severe lead poisoning. The growing scientific literature on lead’s effects, as we will see, has been bitterly contested by the lead industry at every step and has resulted in some classic instances of attempted intimidation of university researchers and attacks on their scientific integrity.³⁸

      The extensive documentation of low-level effects over recent decades has led the Centers for Disease Control to progressively lower the blood lead levels considered to put children at risk. Until the late 1960s, most public health officials and physicians believed that 60 micrograms per deciliter of blood was not dangerous for children. But by 1978 the CDC had halved this figure, reducing it still further in 1985, to 25 μg/dl, and then in 1991 to 10 μg/dl.³⁹ Jane Lin-Fu, a leading lead researcher, has observed that today “we know that normal [blood-lead level] should be near 0, that unlike essential elements such as calcium . . . lead has no essential role in human physiology and is toxic at a very low level.”⁴⁰ Most prominent researchers agree with Lin-Fu’s assessment.⁴¹ Indeed, the CDC’s lead advisory committee, the scientific body that consults on the federal definition of lead poisoning, recommended in January 2012 that the level of concern for lead be cut in half, to 5 μg/dl. This was adopted by the CDC later that year.⁴² The political implications of this recommendation are profound and contentious, however. As a result, the number of children considered at risk of lead poisoning rose dramatically, from an estimated 250,000 children with levels above 10 μg/dl to as many as 450,000 with levels exceeding 5 μg/dl, placing renewed pressure on government, industry, and public health officials to take action.

      Lowering the overall exposure of children to lead entails eliminating the wide variety of ways that children come in contact with lead in their everyday lives. Newspapers are filled with stories of children who have been poisoned by the lead paint on imported toys, lead solder on children’s jewelry, lead from pipes that deliver water to homes, lead in soil tainted by leaded gasoline that once powered cars, lead spewed from smelters in the United States and throughout the world, and, still most importantly, lead from paint that remains on the walls of nearly all houses built before 1960 or that was applied in many other homes until lead paint was banned in 1978.

      Just as there have been disagreements over what constitutes a “safe” blood lead level, so too have there been debates about how best to protect children from lead in their homes. In 1991 the CDC, under the auspices of the U.S. Department of Health and Human Services, published its Strategic Plan for the Elimination of Childhood Lead Poisoning,⁴³ which some prominent researchers called “a truly revolutionary policy statement.”⁴⁴ This document, building on an extensive period of reevaluation among researchers of childhood lead poisoning, proposed “a society-wide effort [to] virtually eliminate this disease as a public health problem in 20 years.”⁴⁵ The document’s publication led to a host of studies seeking ways to eliminate or at least broadly curtail lead poisoning in America. While some researchers developed protocols aimed at eliminating lead as a widespread urban pollutant through its complete removal, others sought more pragmatic solutions—pragmatic, that is, from the viewpoint of the politics of the times, not from that of families whose children were at risk of permanent brain damage—seeking to remove some if not all lead from the windowsills, walls, ceilings, and woodwork of older homes.

      The debate in the early 1990s over what should be done developed in a dramatically altered political environment, as memories of the Great Society were replaced by a more conservative political culture. The rise of Reaganism after 1980, the growing power of corporations, the decline of the civil rights and labor movements, the end of the construction of low-income public housing, and the antigovernment rhetoric and attacks on what were considered liberal social reforms all undermined support for more far-reaching solutions to the lead-poisoning problem. As Herbert Needleman, a pioneer in the early studies of low-level lead neurotoxicity, put it: “Instead of asking, ‘how can we develop a plan to spend U.S. $32 billion over the next 15 years and eliminate all of the lead in dangerous houses?’ the question became, ‘how little can we spend and still reduce the blood-lead levels in the short term?’” Opposition from industry, landlords, and others was so strong, and the countervailing voices so few, said Needleman, that “it was not long before the vision of the early 1990s, true primary prevention, eradication of the disease in 15 years, was replaced by an enfeebled pseudopragmatism,” which came down to only partial abatement of polluted homes.⁴⁶

      One researcher’s pseudopragmatism, however, is another advocate’s realistic attempt to help children at risk. And one person’s policy failure is another’s public health success story. Those who have watched a century of children sacrificed on the altar of lead poisoning are aghast that we, as a wealthy industrial society, would continue to knowingly allow future generations of children to be exposed to lead. In contrast, those who have set their sights lower and labored to reduce rather than eliminate lead in children’s environment, believing this to be the only “practical” course, celebrate dramatic declines in both blood lead levels and symptomatic children as among the great successes in public health history.

      THE KENNEDY KRIEGER CASE AND THE ETHICS OF LEAD RESEARCH

      The lead researchers at Johns Hopkins’s Kennedy Krieger Institute faced a troubling dilemma in the midst of this history: children living in Baltimore, the epicenter of the lead-poisoning epidemic for almost a century, were being poisoned because their homes had been covered with lead paint, which, when it deteriorated, the children inhaled or ingested. Despite the CDC’s grand vision of eliminating lead from the home, it was highly unlikely that the money necessary for a dramatic federal detoxification program would be appropriated: during the Reagan and first Bush administrations, government social projects were defined as part of the problem, not a part of the solution. It was in this general context that the Environmental Protection Agency funded the Kennedy Krieger Institute: the federal government, and various lead researchers, were looking for relatively inexpensive, nonconfrontational, noncoercive methods of partial abatement so that landlords would reduce the lead hazard to children rather than either evade an abatement law or abandon their properties.⁴⁷

      “The purpose of the study,” wrote Mark Farfel, the co-principal investigator with Julian Chisolm, “is to characterize and compare the short and long-term efficacy of comprehensive lead-paint abatement and less costly and potentially more cost-effective Repair and Maintenance (R&M) interventions for reducing levels of lead in residential house dust which in turn should reduce lead in children’s blood.”⁴⁸ “R&M,” as Farfel later put it in a grant renewal request, “may provide a practical means of reducing lead exposure for future generations of children who will continue to occupy older lead-painted housing which cannot be fully abated or rehabilitated without substantial subsidy.”⁴⁹ In the struggle to prevent lead poisoning, there was no question in the researchers’ minds as to what was ultimately needed: the complete removal of lead paint. But “repair and maintenance” was a compromise they made in the hopes of doing at least some good in a difficult time.

      The Farfel and Chisolm study was designed to test the efficacy of three different methods of lead reduction in older homes. The investigators then planned to contrast results with those of two control groups: one of children living in homes that had previously undergone what was thought to have been full lead abatement and the second of children living in homes built after 1978 and presumed to be lead free. For the study, more than a hundred parents with young children were recruited to live in the various partially lead-abated houses. The premise of the research was that children would now be in a safer environment, a home that was an improvement over the lead-covered homes that were generally available to poor residents of Baltimore. However, the blood lead levels of children in at least two of the homes rose over the course of the study.⁵⁰ It was the two sets of parents of these children who filed the lawsuits alleging that they had not been

Скачать книгу