was no safe level of lead exposure, in part because its deleterious effects were irreversible.

In April 1979, in the same week the New England Journal paper on lead poisoning came out, Eskenazi interviewed with Needleman for a job at Harvard. Eskenazi — a proud alumna of Flushing High School, Queens College, and Woodstock Nation (she attributes her original interest in neuropsychology to watching a young man at the music festival who dove headfirst into the pavement while tripping) — had just gotten a Ph.D. at the City University of New York, and one of her first research projects focused on lead. She didn’t get the job, but she and a new generation of environmental epidemiologists considered Needleman’s paper revolutionary. “It was like the first really good study tostudy focused on chlorpyrifos. It is the most widely used insecticide in the country, according to the EPA, even though its use has declined since Rauh and Eskenazi began their studies; farmers use it on everything from Georgia peaches and California tree nuts to Kansas corn and Christmas trees grown in Oregon. The women in the Columbia study, mostly African-American or of Dominican ancestry, encountered chlorpyrifos because it was also widely used at the time as the active ingredient in household insecticides, including Raid. EPA scientists became so concerned about the possible health effects that in 2000 the agency began to phase in a ban on most residential uses of the chemical.

The Columbia group has followed approximately 370 children who were born to women exposed during pregnancy. Every