California intends to list four chlorinated compounds as carcinogens under the state’s Proposition 65. This move would trigger requirements for labeling products that contain these chemicals, the state said in a July 26 notice. The substances are chloral (also known as trichloroacetaldehyde), chloral hydrate, 1,1,1,2-tetrachloroethane, and trichloroacetic acid. California’s Environmental Protection Agency proposed listing the compounds on the basis of determinations by the World Health Organization’s International Agency for Research on Cancer. According to IARC, chloral and chloral hydrate are “probably carcinogenic to humans,” whereas 1,1,1,2-tetrachloroethane and trichloroacetic acid are “possibly carcinogenic to humans.” Proposition 65 mandates that the state list chemicals that IARC deems to be human or animal carcinogens. That 1986 state law requires warning labels on products that contain listed substances and prohibits their discharge into drinking water sources. The public has until Aug. 26 to comment on the proposal.