Please explain the de minimis concentration limitation under Section 313, and its application to mixtures and trade name products (40 CFR Section 372.38(a))?
The de minimis exemption allows covered facilities to disregard certain minimal concentrations of listed non-PBT chemicals in mixtures or trade name products when making threshold determinations and release and other waste management determinations. The de minimis exemption does not apply to the manufacture of a listed toxic chemical except if that listed toxic chemical is manufactured as an impurity and remains in the product distributed in commerce below the appropriate de minimis level or is imported below de minimis concentrations. The de minimis exemption does not apply to a byproduct manufactured coincidentally as a result of manufacturing, processing, otherwise use, or any waste management activity. The de minimis exemption does not apply to the PBT chemicals listed at 40 CFR section 372.28.
When determining whether the de minimis exemption applies to a listed non-PBT chemical, the owner/operator should consider only the concentration of the listed toxic chemical in mixtures and trade name products. If the listed non-PBT chemical in a mixture or trade name product is manufactured as an impurity or imported, processed, or otherwise used and is below the appropriate de minimis concentration level, then the quantity of the listed toxic chemical in that mixture or trade name product does not have to be applied to threshold determinations nor included in release or other waste management calculations. If a listed non-PBT chemical in a mixture or trade name product meets the de minimis exemption, all releases and other waste management activities associated with the listed toxic chemical in that mixture or trade name product are exempt from EPCRA Section 313 reporting. It is possible to meet an activity (e.g., processing) threshold for a toxic chemical on a facility-wide basis, but not be required to calculate releases or other waste management quantities associated with a particular mixture or trade name product because that mixture or trade name product contains the non-PBT chemical below the de minimis level.
Once a listed toxic chemical concentration is above the appropriate de minimis concentration, threshold determinations and release and other waste management calculations must be made, even if the chemical later falls below the de minimis level in the same process stream. Thus, all releases and other quantities managed as waste that occur after the de minimis level has been exceeded are subject to reporting. If a listed toxic chemical in a mixture or trade name product above the de minimis level is brought on-site, the de minimis exemption never applies.
The de minimis concentration level is consistent with the OSHA Hazard Communication Standard requirements for development of Material Safety Data Sheets (MSDSs). The de minimis level is 1.0 percent except if the listed toxic chemical is an OSHA-defined carcinogen. The de minimis level for OSHA-defined carcinogens is 0.1 percent. For mixtures or other trade name products that contain one or more members of a listed Section 313 toxic chemical category, the de minimis level applies to the aggregate concentration of all such members and not to each individually. The list of toxic chemicals in the publication Toxic Chemical Release Inventory Reporting Forms and Instructions for the current reporting year contains the de minimis values for each of the non-PBT chemicals and chemical categories. This de minimis exemption applies solely to mixtures and other trade name products. EPA’s long-standing interpretation has been that mixture does not include waste. Therefore, the de minimis exemption cannot be applied to toxic chemicals in a waste. Additional guidance on the de minimis exemption can be found in Directive #2 of the Addendum to 1998 Question and Answer Document.