An explosion at a chemical factory near Seveso, Italy, in 1976 exposed factory workers and local residents to the pollutant dioxin, presenting an opportunity to track how exposure at different ages affects sperm quality.
Now, results from a new study point to a window of vulnerability in reproductive system development when such chemical disruptions may leave a permanent mark. “The timing is very important,” says study co-author Larry Needham of the Centers for Disease Control and Prevention (CDC) in Atlanta.