The California Trucking Assn., the American Trucking Assns., the California Bus Assn. and construction industry groups filed the suit in California state court in San Diego. The lawsuit says that CARB used old railroad worker diesel exhaust exposure studies to come up with a "unit risk" for lung cancer.
Using that information, CARB and its Scientific Review Panel calculated that 450 out of every million state residents could get lunch cancer if they were continuously exposed for 70 years to 1 microgram of diesel exhaust particulate matter per cubic meter of air.
Because diesel engines and fuels continue to get cleaner, the lawsuit says, it is not fair to target diesel exhaust as a whole as a toxic air contaminant.
The suit claims that CARB's Office of Environmental Health Hazard Assessment manipulated the railroad worker data to support the conclusion it wanted to make - that diesel exhaust causes cancer. Both the Health Effects Institute and U.S. EPA's Clean Air Scientific Advisory Committee have publicly stated that the railroad studies don't support the diesel toxicity listing.
"CARB's diesel TAC listing was an arbitrary political decision based neither on the 'best available scientific evidence' nor on 'sound scientific knowledge,'" the lawsuit says.
This is not the first time CARB's use of the railroad studies has been attacked. In 1997, the Engine Manufacturers Assn. denounced the agency's proposal for its bad science.