Environmental Law Foundation, Communities for a Better Environment and Our Children’s Earth Foundation are asking a court in San Francisco to require Laidlaw, the nation’s largest school bus contractor to place warning signs about diesel exhaust on school buses throughout California. The signs would warn children and parents about cancer risks created by diesel exhaust that enters the buses from the engines and exhaust train. The groups filed for an injunction asking the court to order warnings before the next school year. The request is part of a lawsuit brought by the groups in 2006 under California’s Proposition 65, which requires warnings about cancer risks before people are exposed to a list of chemicals “known to the state to cause cancer.” California placed diesel engine exhaust on the list in 1990. Papers filed with the motion, however, suggest that Laidlaw’s San Francisco division has far more to worry about than placing cancer warnings on buses. Details and downloads.