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Extremely Hazardous Substances


The term "Extremely Hazardous Substances," acronym EHSs, can refer to chemicals listed under two different regulatory programs. Most often, the term refers to EHSs identified under the Emergency Planning and Community Right-to-Know Act (EPCRA). However, it can also refer to substances regulated by Delaware’s Accidental Release Prevention (ARP) Program.

EHSs under EPCRA
In 1986, the federal Superfund Amendments and Reauthorization Act (SARA) was signed into law. Title III of SARA was a free-standing statute known as the Emergency Planning and Community Right-to-know Act (EPCRA). EPCRA was designed to require state and local planning and preparedness for spills or releases of certain hazardous materials, and to provide the public and local governments with information concerning potential chemical hazards in their communities. The statute required the U.S. Environmental Protection Agency (EPA) to publish a list of EHSs , which would identify chemical substances that could cause serious irreversible health effects from accidental releases.  Identification of these substances helps to provide focus for emergency planning activities.  

Companies with EHSs can be subject to a number of regulatory requirements. In 1991, Delaware established its own EPCRA law, which essentially mirrored the federal reporting requirements, but was more stringent in several areas. For each listed EHS, a "threshold planning quantity" (TPQ) and "reportable quantity" (RQ) have been established. Companies with one or more EHSs on site above the TPQ must submit notification and participate in emergency planning. If an EHS is released in an amount exceeding the designated RQ, immediate notifications must be made to specific agencies and organizations. Companies with EHSs onsite can also be subject to annual and periodic chemical inventory reporting under EPCRA Section 312  and may be required to have Material Safety Data Sheets available at the facility.

EHSs under ARP
Delaware was the third state in the nation to develop a chemical accident prevention regulation with adoption of the Regulation for the Management of Extremely Hazardous Substances in September 1990. This regulation was developed under authority of Delaware’s Extremely Hazardous Substances Risk Management Act. While there is some overlap, EHSs identified under this Delaware law are not the same as EHSs identified under EPCRA. In subsequent years, federal ARP regulations have been developed under the Clean Air Act Section 112r. The federal regulations do not use the EHS terminology. Delaware’s ARP Program has since revised the Delaware regulation to encompass both the State and federal requirements. Now known as the State of Delaware’s "Accidental Release Prevention Regulation" (rather than the Regulation for the Management of Extremely Hazardous Substances), it contains requirements for owners or operators of stationary sources having regulated substances onsite to develop and implement a risk management program that anticipates and minimizes the chances of catastrophic events. While the latest regulation for this program refers to covered chemicals primarily as regulated toxic, flammable, or explosive substances, the EHS terminology is sometimes still used to refer to these substances because of the language in the original Delaware Act.

Who Can I Contact for More Information About EHS?

EPCRA Reporting Program
Suite 5 N 
Dover, Delaware 19901
Phone: (302) 739-9405
Fax: (302) 739-3106

Accidental Release Prevention Program
715 Grantham Lane
New Castle, DE 19720
Phone: (302) 323-4542
Fax: (302) 323-4598
Email: or



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