The extremely hazardous substances (EHS) list is intended to hep communities focus on the substances and facilities of the most immediate concern for emergency planning and response.

The purpose of the extremely hazardous substance list is to focus initial efforts in the development of State and local contingency plans. It is not intended to be a complete list of all chemicals that could potentially be hazardous to a community. The identification of a chemical that meets the EHS criteria does not in itself indicate the potential for serious effects in any release, accidental or routine. Thus, inclusion on the EHS list is not meant as a signal to state or local communities to ban or otherwise restrict use of a listed chemical. Rather, such identification indicates a need for the community to undertake a program to investigate and evaluate the potential for accidental exposure associated with the production, storage or handling of the chemical at a particular site. EPA also encourages communities to go beyond the EHS list when evaluating the hazards of facilities in their community, in that facilities handling chemicals not on the EHS list could be as hazardous as those handling EHSs.

The List of Extremely Hazardous Substances and Their Threshold Planning Quantities