On May 10, 2007, the Toxics Release Inventory Program issued a final rule expanding reporting requirements for the dioxin and dioxin-like compounds category. There are seventeen distinct members of this chemical category listed under TRI. The final rule requires that, in addition to the total grams released for the entire category, facilitiesmust report the quantity for each individual member on a new Form R Schedule 1. EPA will then use the individual mass quantity data to calculate TEQ values that will be made available to the public along with the mass data. The final rule also removes the requirement to report the single distribution of compounds in the category. EPA currently requires that facilities report, in grams, the total amount ofdioxin and dioxin-like compounds released from the facility. When available, the facility must also provide a single distribution, showinghow that total is divided among the individual dioxin and dioxin-like compounds. This single distribution must represent either total releases, or releases to the media (air, land, water) for which the facility has the best information. Although useful, total releases are not the best measure of the actual toxicity of these compounds because each compound has its own level of toxicity. To account for how compounds vary in toxicity, we use weighted values called toxic equivalents (TEQs). To calculate TEQs, we assign a value describing how toxic each dioxin and dioxin-like compound is compared to the most toxicmembers of the category: 2,3,7,8-tetrachlorodibenzop- dioxin and 1,2,3,7,8-pentachlor odibenzo-p-dioxin. Expressing data for dioxin and dioxin-like compounds as TEQs allows the public to understand the toxicity of releases and waste management at facilities that report under the TRI program. For example, a facility releasing 3 grams of somecombination of dioxin and dioxin-like compounds may or may not be of greater interest than a facility releasing 1 gram of a different combination. However, a facility releasing 3 grams TEQ of dioxins is of greater environmental importance than one releasing 1 gram TEQ to the same environmental medium (e.g., air, land, water).