((a)) The Administrator shall promulgate and revise as may be appropriate, regulations designating as hazardous substances, in addition to those referred to in , such elements, compounds, mixtures, solutions, and substances which, when released into the environment may present substantial danger to the public health or welfare or the environment, and shall promulgate regulations establishing that quantity of any hazardous substance the release of which shall be reported pursuant to . The Administrator may determine that one single quantity shall be the reportable quantity for any hazardous substance, regardless of the medium into which the hazardous substance is released. For all hazardous substances for which proposed regulations establishing reportable quantities were published in the Federal Register under this subsection on or before , the Administrator shall promulgate under this subsection final regulations establishing reportable quantities not later than . For all hazardous substances for which proposed regulations establishing reportable quantities were not published in the Federal Register under this subsection on or before , the Administrator shall publish under this subsection proposed regulations establishing reportable quantities not later than , and promulgate final regulations under this subsection establishing reportable quantities not later than .”

((b)) Unless and until superseded by regulations establishing a reportable quantity under subsection (a) of this section for any hazardous substance as defined in , (1) a quantity of one pound, or (2) for those hazardous substances for which reportable quantities have been established pursuant to , such reportable quantity, shall be deemed that quantity, the release of which requires notification pursuant to section 9603(a) or (b) of this title.