On a Southern California spring morning in 1973, a tanker truck driver jackknifed his rig and dumped the agricultural fumigant he was transporting onto a city street. A Los Angeles Fire Department emergency response team spent four hours cleaning up the chemical, 1,3-dichloropropene, or 1,3-D, a fumigant sold as Telone that farmers use to kill nematodes and other soil-dwelling organisms before planting.