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TRI National Analysis

Releases of Chemicals

Helpful Concepts

What is a release?

In the context of TRI, a “release” of a chemical generally refers to a chemical that is emitted to the air, discharged to water, or disposed of in some type of land disposal unit. The majority of TRI releases happen during routine production operations at facilities. To learn more about what EPA is doing to help limit the release of TRI chemicals into the environment, see the EPA laws and regulations webpage.

ReleasesHelpReleasesAny spilling, leaking, pumping, pouring, emitting, emptying, discharging, injecting, escaping, leaching, dumping, or disposing into the environment (including the abandonment or discarding of barrels, containers, and other closed receptacles) of any toxic chemical. [42 U.S.C. §11049 (8)] [40 CFR § 372.3] or disposalHelpDisposalAny underground injection, placement in landfills/surface impoundments, land treatment, or other intentional land disposal. [40 CFR § 372.3] of chemical waste into the environment occur in several ways. Facilities may release chemical waste directly into the air or water or dispose of it on land, or ship (transfer) wastes that contain TRI chemicals to an off-site location for disposal. Release and disposal practices are subject to a variety of regulatory requirements and restrictions designed to minimize potential exposure or harm to human health and the environment.

Facilities are required to report the quantities of TRI-listed chemicals they released to the environment. Evaluating release data can help to:

It is important, however, to understand that the quantity of releases is not necessarily an indicator of health impacts posed by the chemicals. Potential risks to human health from releases of TRI chemicals are determined by many factors, as discussed in the Hazard and Potential Risk of TRI Chemicals section.

The following graph shows the change in total disposal or other releases of TRI chemicals (also referred to as “total releases”) over time. Many factors can affect trends in releases at facilities, including production rates, management practices, the composition of raw materials used, and the installation of control technologies.


Note: For comparability, trend graphs include only those chemicals that were reportable to TRI for all years presented.

From 2007 to 2019:

  • Total disposal or other releases of TRI chemicals decreased by 19%.
    • Excluding the metal mining sector, releases decreased by 37%.
    • Reduced hazardous air pollutant (HAP) emissions, such as hydrochloric acid, from electric utilities were the most significant contributor to the decline.
  • Releases to air decreased by 57%, discharges to surface water decreased by 16%, and off-site disposal decreased by 21%.
  • Releases to land, driven by the metal mining sector, increased by 7%.
  • The number of facilities that reported to TRI declined by 9%.

From 2018 to 2019:

  • Total disposal or other releases decreased by 9%.
    • On-site land disposal decreased by 13%, which is the main driver for the decrease in total releases.
    • Quantities released to air on site decreased slightly, while quantities discharged on site to surface water and transferred off site for disposal increased slightly.
  • Please note that the most recent TRI dataset reflects chemical waste management activities that occurred during calendar year 2019, and therefore does not indicate any potential impacts of the COVID-19 pandemic, which began in the U.S. in early 2020.

TRI Data Considerations

As with any dataset, there are several factors to consider when using the TRI data. Key factors associated with data used in the National Analysis are summarized in the Introduction. For more information see Factors to Consider When Using Toxics Release Inventory Data.

This page was published in January 2021 and uses the 2019 TRI National Analysis dataset made public in TRI Explorer in October 2020.

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