Dioxins
This chemical profile focuses on releases of dioxin and dioxin-like compounds.
Dioxins are typically produced in very small quantities compared to other chemicals, but are toxic at much lower concentrations than most other chemicals. Additionally, they persist in the environment and bioaccumulate in the food web. Therefore, dioxins have a lower reporting threshold and are reported in grams instead of pounds to capture smaller amounts of these chemicals.
This map shows the locations of the facilities that reported dioxins to TRI for 2021, sized by their relative release quantities. Zoom in to view demographic data for communities around these facilities. Click on a facility for more details on its reporting.
Click on any one of the locations on the map to see detailed information.
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Toxic Equivalent Factor (TEF)
Each dioxin congener is assigned a TEF that compares that compound’s toxicity to the most toxic dioxin in the category.
Toxic Equivalency (TEQ)
A TEQ is calculated by multiplying the reported grams of each congener by its corresponding TEF and summing the results, referred to as grams-TEQ.
Dioxin and dioxin-like compounds (“dioxins”) are persistent bioaccumulative toxic (PBT) chemicals characterized by EPA as probable human carcinogens.
TRI requires facilities to report data on the 17 individual members (congeners) of the TRI dioxin and dioxin-like compounds category. While each of the dioxin congeners causes the same toxic effects, some cause these effects at lower levels of exposure than others because congeners have different toxicities. As a result, one mixture of dioxins can have a very different toxic potency than the same amount of a different mixture. Facilities in different sectors release different mixtures of dioxins depending on their operations, so the potential for harm from their releases may also be different.
EPA accounts for the different toxicities of the dioxin congeners by using Toxic Equivalency (TEQ) values. TEQs help to understand the toxicity of dioxin releases. They are most useful when comparing releases of dioxins from different sources or different time periods, where the mix of congeners may vary.
This graph shows the 10-year trend in the quantity of dioxins that facilities released from 2012 to 2021. Note that the dioxins chemical category is reported in grams while all other TRI chemicals are reported in pounds.
From 2012 to 2021:
- Dioxin releases increased by 27%. Most of this increase can be attributed to increased releases from two organic chemical manufacturing facilities and one hazardous waste management facility.
- Toxicity equivalents (grams-TEQ) decreased by 8%, indicating that the overall toxicity of dioxin releases decreased despite an increase in the quantity released. This is due to changes in which dioxin congeners were released.
From 2020 to 2021:
- Releases of dioxins decreased by 25%, driven by decreased releases reported by one hazardous waste management facility in Alabama.
- Toxicity equivalents (grams-TEQ) decreased by 3%, indicating changes in the dioxin congener composition reported from 2020 to 2021. Although facilities released lower total quantities of dioxins, a higher proportion of dioxin releases were more toxic congeners.
- In 2021, 61% of dioxin releases were disposed off site, primarily in landfills.
Dioxins Releases by Industry
The following two pie charts compare the industry sectors that reported the greatest releases of dioxins (in units of grams) to those that reported the greatest releases of dioxins based on toxicity equivalency (in units of grams-TEQ).
- Various industry sectors may release very different mixes of dioxin congeners.
- The chemical manufacturing industry accounted for 72% and the primary metals sector for 12% of total grams of dioxins released.
- In terms of toxicity equivalents, however, the primary metals sector accounted for 46% and the chemical manufacturing sector for 22% of the total grams-TEQ.
This page was published in March 2023 and uses the 2021 TRI National Analysis dataset made public in TRI Explorer in October 2022.