Frequent Questions

De minimis exemption and wastestreams

A small quantity of a listed toxic chemical is manufactured in a wastestream. Are facility owners/operators required to include the amount of the listed toxic chemical present in the wastestream as part of the threshold determination if the concentration of the listed toxic chemical in the wastestream is below the de minimis level?

Yes. This de minimis exemption applies solely to non-PBT chemicals in mixtures. EPA’s long-standing interpretation has been that mixture does not include waste. Also, generally, de minimis does not apply to listed toxic chemicals that a facility manufactures. The de minimis exemption cannot be applied to listed toxic chemicals manufactured as a byproduct. Additional guidance regarding the de minimis exemption can be found in Directive #2 of the Addendum to 1998 Question and Answer Document and the Revised 1998 EPCRA Section 313 Questions and Answers Document.

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