Tyrone Hayes proved that agricultural runoff containing the weedkiller atrazine chemically castrates male leopard frogs by forcing their bodies to produce an enzyme called…

A closer look

Chemical companies accidentally engineered a gender-bending potion for amphibians, and it's floating in our water supply. Environmental endocrine disruption happens when synthetic chemicals mimic or block natural hormones. The popular herbicide atrazine triggers a terrifying biological override in male frogs: it activates the aromatase enzyme, which literally cannibalizes the frog's testosterone and converts it into estrogen. These genetically male frogs end up growing viable ovaries, entirely redefining what agricultural runoff does to developmental biology.