Toxic Release Inventory data for 2024. 162 facilities reported releasing maleic anhydride.
The Toxic Release Inventory (TRI) tracks how much of each listed chemical U.S. industrial facilities release into the environment each year. EPA requires facilities in certain industry sectors that manufacture, process, or otherwise use TRI-listed chemicals above threshold amounts to report annually. In 2024, 162 facilities reported releasing maleic anhydride to EPA's TRI program.
Releases are spread across all three environmental pathways: 151.3k lb to air (stack and fugitive emissions), 344 lb to water (surface water discharges), and 522.0k lb to land (landfills, surface impoundments, and land treatment).
TRI data represents reported releases, not measured environmental concentrations. A facility reporting large releases of maleic anhydride is not necessarily causing harm at those levels — toxicity, exposure pathways, and local conditions all matter. Conversely, small reported amounts of highly toxic chemicals can pose greater risk than large amounts of less toxic ones. TRI is a transparency tool, not a risk assessment.
For health information about specific chemicals, the Agency for Toxic Substances and Disease Registry (ATSDR) publishes toxicological profiles, and EPA's Integrated Risk Information System (IRIS) provides reference doses and cancer classifications.