Extremely Hazardous Substance in the United States

Extremely Hazardous Substance (EHS) in Environmental Law

An acutely toxic substance enumerated on the Environmental Protection Agency’s (EPA) list of Extremely Hazardous Substances by authority of the Emergency Planning and Community RightToKnow Act.

The list serves as a reference, informing facilities of their responsibilities under this statute. In addition to the name of the substance, the list gives two other necessary pieces of information. First, it states the threshold planning quantity; second, it specifies a reportable quantity.

The threshold planning quantity is the amount of the substance that triggers requirements to report its existence to emergency planning agencies. The reportable quantity figure determines the amount of the EHS released to the environment that must be reported. Chlorine, for example, has a threshold planning quantity of 100 pounds; nicotine, 100 pounds; and mustard gas, 500 pounds. A facility with any of those EHSs in the amount specified must file information for emergency response planning.

Reportable quantities has also been established for the same chemicals: chlorine, 10 pounds; nicotine, 100 pounds; and mustard gas, 1 pound. Therefore, if a facility spills 10 or more pounds of chlorine, 100 or more of nicotine, or 1 or more of mustard gas into the environment, it must report the spill to the responsible agencies.

Initially 406 substances were listed as extremely hazardous; the list was later reduced when the EPA found that some of the substances listed were not acutely toxic. Recently, however, it has proposed adding 313 substances to the list.
Based on “Environment and the Law. A Dictionary”.