Toxics Release Inventory (TRI) Program

TRI Dioxin and Dioxin-like Compounds Toxic Equivalency (TEQ) Information

Final Rule

On May 10, 2007, the Toxics Release Inventory (TRI) 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, facilities must 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 of dioxin and dioxin-like compounds released from the facility. When available, the facility must also provide a single "distribution," showing how 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 toxic members of the category: 2,3,7,8-tetrachlorodibenzo-p-dioxin and 1,2,3,7,8-pentachlorodibenzo-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 some combination 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).

TEQs will allow the public to make more informed environmental decisions within their communities. Expressing dioxin releases and waste management information in grams TEQ will also permit easier comparisons between TRI data and other EPA and international data.

TRI Dioxin and Dioxin-like Compounds Toxic Equivalency Final Rule (PDF) (11 pp, 219 K)

TRI Dioxin and Dioxin-like Compounds Toxic Equivalency Proposed Rule (PDF) (12 pp, 223 K)


What are dioxin and dioxin-like compounds?

Dioxin and dioxin-like compounds are trace level unintentional byproducts of some forms of combustion and several industrial chemical processes. They are not commercial chemical products.

Dioxins are transported primarily through the air and are deposited on surfaces; they have been detected in air, soil, sediments and food. The principal route by which dioxins are introduced to most rivers, streams and lakes is soil erosion and storm water runoff from urban areas. Industrial discharges can significantly elevate water concentrations near the point of discharge to rivers and streams. Major contributors of dioxin to the environment include:

  • Incineration of municipal solid waste
  • Incineration of medical waste
  • Secondary copper smelting
  • Forest fires
  • Land application of sewage sludge
  • Cement kilns
  • Coal fired power plants
  • Residential wood burning
  • Chlorine bleaching of wood pulp

Backyard burning of household waste may also be an important source.

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What is a TEQ and how is it calculated?

TEQs are calculated values that allow us to compare the toxicity of different combinations of dioxins and dioxin-like compounds. The two most toxic compounds are the comparison point. For example, a mixture weighing 10g with a TEQ of 5g would be as toxic as 5g of either of the two most toxic compounds.

In order to calculate a TEQ, a toxic equivalent factor (TEF) is assigned to each member of the dioxin and dioxin-like compounds category. The TEF is the ratio of the toxicity of one of the compounds in this category to the toxicity of the two most toxic compounds in the category, which are each assigned a TEF of 1: 2,3,7,8-tetrachlorodibenzo-p-dioxin (commonly referred to as dioxin) and 1,2,3,7,8-pentachlorodibenzo-p-dioxin. TEFs that have been established through international agreements currently range from 1 to 0.0001.

A TEQ is calculated by multiplying the actual grams weight of each dioxin and dioxin-like compound by its corresponding TEF (e.g., 10 grams X 0.1 TEF = 1 gram TEQ) and then summing the results. The number that results from this calculation is referred to as grams TEQ.

For example, consider the following 60g mixture:
10g of compound A, with a TEF of 1
20g of compound B, with a TEF of 0.5
30g of compound C, with a TEF of 0.2.

The TEQ of this mixture would be:
(10g x 1) + (20g x 0.5) + (30g x 0.2) = 26g TEQ,

In other words, this mixture of 60g of various compounds would be as toxic as 26g of either of the two most toxic compounds.

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Why are TEQs useful? What are their drawbacks?

Using TEQs helps people understand the relative toxicity of the chemical release information. For example, it is not possible to conclude that two facilities, each releasing 2 grams of dioxin and dioxin-like compounds are of equal environmental importance without considering other factors. It may be possible, however, to conclude that two facilities each releasing 2 grams TEQ are of equal importance if the releases from each facility are to the same environmental medium (e.g., air, land, water).

On the other hand, it is not possible on the basis of TEQ alone to establish whether the two sources are making equal strides in release or waste minimization. Instead, it is necessary to know the actual mass of each compound that is released. Together, the mass and TEQ give a full picture that can help guide waste minimization decisions.

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What changes has EPA finalized for the reporting for the dioxin and dioxin-like compounds category under TRI?

EPA is requiring reporting of the individual grams data for each member of the category for each release, by medium, and each waste management process, in addition to the total category grams data currently reported. EPA is eliminating the current requirement to report a single distribution for the dioxin and dioxin-like compounds category, since this information will be redundant under the final rule.

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Q: Why did EPA make these changes to the reporting for dioxin and dioxin-like compounds?

A: The addition of TEQ information will allow further understanding of the releases and waste management quantities currently reported to the TRI for dioxin and dioxin-like compounds. In addition, TEQs make it easier to compare TRI data with other EPA data and international data.

EPA made these revisions in response to requests from TRI reporters that EPA provide facilities with a method of reporting TEQ data to provide important context for dioxin release data. In addition, EPA believes that the public will benefit from the additional context and comparability of data provided by TEQ reporting.

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Q: For what reporting year will the new reporting requirements be effective?

A: The reporting requirements of the final rule apply to the reporting year beginning January 1, 2008, (for which reports are due July 1, 2009), and to subsequent reporting years. EPA has delayed the implementation of the reporting requirements of this final rule in order to provide sufficient time and resources to make required changes to the TRI database and the TRI-Made Easy (TRI-ME) reporting software. In addition, delaying the implementation will allow more time for the regulated community to become fully aware of the new reporting requirements. The additional time to prepare for the reporting changes should also promote more accurate and consistent reporting.

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Will TEQ data be available for all reports of releases and waste management data for dioxin and dioxin-like compounds?

TRI reporters are not required to collect new data or undertake monitoring for use in completing Form Rs or Form A Certification Statements, and will not be required to do so to complete the new Form R Schedule 1. Instead, facilities use the best information they have available or estimate information to be reported.

For reporting year 2003, there were 1,268 facilities that filed Form Rs for dioxin and dioxin-like compounds. Of these facilities, 75 percent (956 facilities) completed section 1.4 of the Form R containing distribution information on the members of the category. The 312 facilities that did not complete section 1.4 are unlikely to be able to provide individual grams data for each member of the category and therefore are unlikely to be able to calculate a TEQ value or provide EPA sufficient information that EPA could calculate a TEQ value.

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How much will the change in reporting requirements cost?

The total incremental cost to industry is estimated at $114,000 in the first reporting year and $38,000 in subsequent reporting years.

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Who has to report releases and other waste management information for dioxin and dioxin-like compounds?

Any facilities in specified North American Industry Classification System (NAICS) codes with 10 or more employees that exceed the reporting thresholds for dioxin and dioxin-like compounds and meet the other TRI reporting criteria must file a report. The individual sectors and facilities reporting on the TRI dioxin and dioxin-like compounds category will not change as a result of this rule.

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