Q. For TRI reports, are the quantities of a single listed toxic chemical present in two different mixtures added together for threshold determination calculations when the quantity in one mixture is below the de minimis level and the quantity in the other mixture is above the de minimis level?

A. In this scenario, the toxic chemical in the mixture below the de minimis level does not have to be included in threshold determinations or release reporting.  Only the quantity of the toxic chemical in the mixture above the de minimis level would be used to make a threshold determination and for release reporting.  

Under 40 CFR 372.38(a)(1), “If a toxic chemical is present in a mixture of chemicals at a covered facility and the toxic chemical is in a concentration in the mixture which is below 1 percent of the mixture, or 0.1 percent of the mixture in the case of a toxic chemical which is a carcinogen, a person is not required to consider the quantity of the toxic chemical present in such mixture when determining whether an applicable threshold has been met under 40 CFR 372.25 or determining the amount of release to be reported under 40 CFR 372.30.  EPA confirms this in its TRI Questions and Answers.

However, 40 CFR 372.38(a)(2) states “this exemption applies only to the quantity of the toxic chemical present in the mixture. If the toxic chemical is also manufactured (including imported), processed, or otherwise used at the covered facility other than as part of the mixture or in a mixture at higher concentrations, in excess of an applicable threshold quantity set forth in 40 CFR 372.25, the person is required to report under 40 CFR 372.30.”