The state of Hawaii is banning a pesticide scientists have found could hinder the development of children’s brains.

Gov. David Ige today signed legislation banning chlorpyrifos. Ige and state lawmakers say Hawaii is the first state to ban the substance.

Chlorpyrifos is among the world’s most widely used pesticides. It’s commonly sprayed on citrus fruits, apples and other crops.

The state may issue exemptions for three years to allow agriculture businesses time to adjust. The law takes effect in January.

EPA Administrator Scott Pruitt last year reversed an effort by President Barack Obama’s administration to bar its use on fruits and vegetables. The Obama administration acted after peer-reviewed academic studies found even tiny levels of exposure could hinder child brain development.