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TRI National Analysis

Chemicals of Special Concern

In this section, we take a closer look at some Toxics Release Inventory (TRI) chemicals that are of special concern due to their potential effects on human health and the environment: 1) persistent bioaccumulative toxic (PBT) chemicals; and 2) known or suspected human carcinogens.

Chemicals designated as PBTs are toxic and remain in the environment for a long time where they tend to build up in the tissues of aquatic or other organisms throughout the food web. These organisms serve as food sources for other organisms, including humans, that are sensitive to the toxic effects of PBT chemicals.

Reporting thresholds for the 16 chemicals and 5 chemical categories designated as PBTs on the TRI chemical list are lower than for other TRI chemicals. Thresholds vary by chemical but range from 10 pounds to 100 pounds for most PBTs, or 0.1 grams for dioxin and dioxin-like compounds. This section focuses on the following PBT chemicals: lead and lead compounds; mercury and mercury compounds; and dioxin and dioxin-like compounds.

There are also chemicals on the TRI chemical list that the Occupational Safety and Health Administration (OSHA) includes on its list of carcinogens. This section presents the trend in air emissions for the OSHA carcinogens reported to TRI and one OSHA carcinogen, ethylene oxide, is highlighted individually. A list of the TRI carcinogens can be found on the TRI basis of OSHA carcinogens webpage.


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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