The EPCRA Section 313 toxic chemical list contains three delimited chemical categories. A delimited category includes a finite number of chemicals specifically designated by EPA to be included as part of that category. Are threshold determinations and release and other waste management calculations for these three delimited chemical categories different than threshold determinations and release and other waste management calculations for other EPCRA Section 313 listed chemical categories?
Threshold determinations are made in the same manner for both delimited and nondelimited categories. If a covered facility manufactures, processes, or otherwise uses more than one member of a listed chemical category, the total volume of all the members of the category must be counted towards the applicable activity threshold (40 CFR Section 372.25(d)). If an activity threshold is exceeded, the owner or operator of the facility is required to report under EPCRA Section 313. The report must cover all non-exempt activities at the facility involving members of the category. The three delimited categories are diisocyanates, dioxin and dioxin-like compounds, and polycyclic aromatic compounds (PACs). The diisocyanates category consists of 20 specific members, the dioxin and dioxin-like compounds category consists of 17 specific members, and the PACs category consists of 21 specific members. For reporting on delimited categories, only the members that are specifically listed as part of the category are subject to EPCRA Section 313 reporting. When reporting other nondelimited chemical categories, any unique chemical substance that contains the named category compound as part of that chemical’s structure, or any compound meeting the specified molecular formula, is subject to threshold determinations. In 1999, (64 FR 58666, October 29, 1999), EPA classified the PACs category as a PBT chemical category and lowered the reporting threshold to 100 pounds. In addition, EPA added two members to this category: benzo(j,k)fluorine (fluoranthene) and 3-methylcholanthrene. EPA has developed guidance to facilitate accurate reporting for PACs entitled Guidance for Reporting Toxic Chemicals: Polycyclic Aromatic Compounds Category, accessible from the TRI web site (www.epa.gov/tri) under the heading “Guidance Documents.” The guidance contains a list of Chemical Abstract Service (CAS) numbers for the individual chemicals within the PACs category and a CAS number list of some mixtures that might containchemicals within the PACs category. The dioxin and dioxin-like compounds category was also classified as a PBT chemical category and a reporting threshold of 0.1 gram was established. EPA has also developed guidance to facilitate accurate reporting for dioxin and dioxin-like compounds; Guidance for Reporting Toxic Chemicals with the Dioxin and Dioxin-like Compounds Category is available from the TRI Web site (www.epa.gov/tri) under “Guidance Documents.”