The TRI Program collects data on a number of different types of disposal or other releases, as well as on certain waste management and recycling practices. For more information on the differences between these data elements, please refer to the Toxics Release Inventory (TRI) and “Factors to Consider When Using TRI Data” on the TRI Web site. Disposal or other releases of chemicals into the environment occur through a range of practices that may ultimately affect the potential for human exposure to the toxic chemicals. Most disposal or other release practices are subject to a variety of regulatory requirements designed to limit environmental harm. Facility releases may include discharges to air, water, and land. Facilities limit contamination and human exposure by disposing of or otherwise releasing waste in certain ways. For example:
• they may dispose of harmful materials in Class I underground injection wells located in isolated formations beneath the lowermost underground source of drinking water, thereby limiting the potential for contamination of drinking water; and
• they may dispose of wastes in landfills that have liners, covers, leak-detection systems, and groundwater monitoring systems, thereby limiting the potential for human exposure to the contents of the landfill.