Chlorpyrifos contamination across the food system Shifting science, regulatory challenges, and implications for public health

Chlorpyrifos is one of the most widely used pesticides in the world since it was developed in the 1960s, yet it is little known by the public despite growing certainty of its harm to human health and the environment. This chapter traces chlorpyrifos’ legacy on the eve of its ban by the EPA, more than three decades since it became the majority replacement pesticide following the ban of DDT. Over-the-counter sales of the chemical ended in 2000 because of the overwhelming evidence of damage to children, but agricultural uses persisted. Over the past three decades, farmworkers' advocates, environmentalists, and environmental health scientists have documented harm in exposed groups and exerted ongoing pressure on regulatory agencies to curb the chemical's use. This article examines the conflict over chlorpyrifos and argues for a food systems and precautionary public health based approach to regulatory decision-making over pesticides. Ongoing contestations by scientists over the meaning and interpretation of chemical exposures despite mounting evidence of widespread population exposures to multiple chemicals require new frameworks for approaching pesticide regulation. The case of chlorpyrifos also raises important questions about replacement chemicals which themselves can prove to be problematic