Helen Epstein is an independent consultant and writer specializing in public health in developing countries, and an adjunct assistant professor at the Columbia University School of International and Public Affairs.

In December 1993, a slum landlord in Baltimore named Lawrence Polakoff rented an apartment to a twenty-one-year-old single mother and her three-year-old son, Max.¹ A few days after they moved in, Max’s mother was invited to participate in a research study comparing how well different home renovation methods protected children from lead poisoning, which is still a major problem endangering the health of millions of American children, many of them poor.

Congress had banned the sale of interior lead paint in 1978, but it remained on the walls of millions of homes nationwide, and there was no adequate federal program to deal with it. In Baltimore, most slum housing contained at least some lead paint, and nearly half of the children who lived in these houses had levels of lead in their blood well above that considered safe by the Centers for Disease Control. Max’s blood lead was low when he moved into Polakoff’s apartment, but Polakoff had been cited at least ten times in the past for violating Baltimore’s lead paint regulations, and several former tenants would later sue him for poisoning their children, so the boy was now in great danger.

The research study in which Max and his mother participated was run by two scientists affiliated with Baltimore’s Johns Hopkins University with support from the US Environmental Protection Agency. The scientists had formed a partnership with a local contractor, who identified slum landlords like Polakoff and urged them to rent preferentially to families with children aged six months to four years, just when they start crawling around the house and when lead exposure is most dangerous to the developing brain. If the parents agreed, their home would receive one of three different types of lead removal and their children—all of whom were healthy and normal and had low blood lead when they joined the study—would be given regular blood tests to see if their lead levels rose or fell.²

The three lead removal methods varied in cost and thoroughness. In twenty-five of the homes, areas with peeling paint were scraped and repainted and a doormat was placed by the main entrance. This was called “level I abatement” and the cost was not to exceed $1,650. Another twenty-five homes received more extensive “level II abatement” in which chipping paint was scraped and repaired, doormats were placed at all entrances, an easy-to-clean floor covering was installed, and collapsing walls were covered with plasterboard. The cost of this was not to exceed $3,500. In a third set of twenty-five dwellings, all of the above was done, but in addition, all windows were replaced. The cost of this “level III abatement” was not to exceed $7,000. Two control groups of twenty-five families each were also recruited into the study. Half lived in houses that had been built after the interior lead paint ban in 1978, and half lived in older houses that were supposed to have been fully renovated in the past.

Max’s apartment received level II abatement. While carrying out the work, the contractor noticed some “hot spots”—areas of lead paint that could shed dangerous dust. He pointed them out to Polakoff, and also recorded their location on forms that were sent to the researchers, but no one told Max’s mother. Because of the cost limits for level II abatement, the hot spots were not repaired. When Max was tested six months later, his blood lead had nearly quadrupled, to a level known to cause permanent brain damage.

In 1990, Leslie Hanes, another young black single woman, moved into an apartment that was supposed to have been fully stripped of lead paint years earlier. In 1992, she gave birth to a daughter, Denisa, and in the spring of the following year, she too joined the toddler lead study.³ The day before Hanes signed the consent form, the contractor found that her apartment was not in fact lead-free. The remaining lead paint was removed, but by the following September Denisa’s blood lead level had more than tripled and was now six times higher than that currently considered safe by the Centers for Disease Control.

Denisa’s mother was not informed of the blood test result for another three months, by which time it was nearly Christmas. The research assistant who told her about it wished her happy holidays and advised her to wash her front steps more carefully and to keep eighteen-month-old Denisa from putting her hands in her mouth. When Denisa eventually entered school, she had trouble keeping up and had to repeat second grade. This came as a surprise to her mother, a former high school honors student. As Hanes told The Washington Post’s Manuel Roig-Franzia in 2001, sometimes Denisa came home crying because she thought she was stupid. “No, baby, you’re not stupid,” Leslie told her. “We just have to work harder.”...