Nigeria, Aug. 4 -- You don't hear the gunshots. You don't see the blood. But in the heart of a quiet farming village just outside Makurdi, people are dying slowly-and nobody seems to care.

Mama Nkechi thought she was doing the right thing. Bought the "high-yield" maize seeds from a glossy-eyed trader who spoke more English than sense. He said it was "modern agriculture." Said she'd harvest triple what her father did. He didn't mention what came next.

A year later, the maize came strong, but the weeds came stronger. So she sprayed. And sprayed. The herbicide's name? Glyphosate. She didn't know what it meant. She only knew it killed weeds fast-and left a strange bitter smell in the air.

Now her youngest son coughs blood every morning. He...