In the 1990s, a prominent research facility associated with Johns Hopkins University conducted an experiment that knowingly exposed children — mostly African American, some as young as a year old — to varying levels of potentially dangerous lead, as part of a study comparing different degrees of lead paint abatement. The researchers, at Hopkins’ Kennedy Krieger Institute, recruited poor families to move into homes that had only been partially abated using three different methods of lead paint removal at three different levels of cost.

The research was “conducted in the best interest of all of the children enrolled,” Dr. Gary W. Goldstein, president and chief executive of the Kennedy Krieger Institute, said in response to a class-action lawsuit filed by the families in 2011. “Over all, the blood lead levels of most children residing in the study homes stayed constant or went down.”

But in some cases, children placed in homes that received the two cheaper forms of abatement were exposed to levels of lead known to cause permanent neurological problems.

Here, public health historians Gerald Markowitz and David Rosner tell the story. You can read about it in more detail in this chapter of their book, Lead Wars.

Watch Bill’s entire interview with Gerald Markowitz and David Rosner.