What is the relationship between CERCLA hazardous substances and the U.S. Department of Transportation's (DOT) Hazardous Materials Regulations?

CERCLA section 306(a), as amended, requires the DOT to list and regulate as hazardous materials all CERCLA hazardous substances. Thus, all CERCLA hazardous substances are covered by the DOT's Hazardous Materials Regulations. The DOT Hazardous Materials Regulations require that when these materials are shipped in quantities equal to or greater than their RQs, and are present in a single package, above certain concentration thresholds, they must be identified as such on shipping papers and by package markings. More information on concentration cutoffs for RQs is available.