When chemical giant Syngenta hired biologist Tyrone Hayes to study its widely used herbicide atrazine, the company didn’t like the results. Hayes found that atrazine, one of the most common weed killers in America, disrupted hormones in frogs and altered their sexual development. Instead of facing the science, Syngenta went into product-defense mode: pressuring Hayes not to publish, and when he did, launching a full-scale effort to discredit him. Internal company documents later revealed a coordinated campaign to smear Hayes’s reputation and bury his findings.

This story is typical of how the world’s largest chemical corporations act when confronted with evidence their products cause harm. Today, just four multinationals dominate the global pesticide market – Bayer, Syngenta, BASF, and Corteva. All of them have long histories of suppressing inconvenient science, manipulating regulators, and attacking critics to weaken regulation and keep their profits flowing. Meanwhile, American children are exposed to many toxic chemicals that are not allowed in other countries.