The insecticide chlorpyrifos is a powerful tool for controlling various pests, making it one of the most widely used pesticides during the latter half of the 20th century.

Like many pesticides, however, chlorpyrifos lacks precision. In addition to harming non-target insects like bees, it has also been linked to health risks for much larger animals – including us.

Now, a new US study suggests those risks may begin before birth. Humans exposed to chlorpyrifos prenatally are more likely to exhibit structural brain abnormalities and reduced motor functions in childhood and adolescence.