Persistent, bioaccumulative and toxic substances

Persistent, bioaccumulative and toxic (PBTs) substances are a class of compounds that have high resistance to degradation from abiotic and biotic factors, high mobility in the environment and high toxicity. Because of these factors PBTs have been observed to have a high order of bioaccumulation and biomagnification, very long retention times in various media, and widespread distribution across the globe. Majority of PBTs in the environment are either created through industry or are unintentional byproducts.

Persistent organic pollutants (POPs) were the focal point of the Stockholm Convention 2001 due to their persistence, ability to biomagnify and the threat posed to both human health and the environment. The goal of the Stockholm Convention was to determine the classification of POPs, create measures to eliminate production/use of POPs, and establish proper disposal of the compounds in an environmentally friendly manner. Currently the majority of the global community is actively involved with this program but a few still resist, most notably the U.S.

Similar to POPs classification, the PBT classification of chemicals was developed in 1997 by the Great Lakes Binational Toxic Strategy (GLBNS). Signed by both the U.S and Canada, the GLBNS classified PBTs in one of two categories, level I and level II. Level I PBTs are top priority which currently, as of 2005, contained 12 compounds or classes of compounds.

The GLBNS is administered by the U.S Environmental Protection Agency (USEPA) and Environment Canada. Following the GLBNS, the Multimedia Strategy for Priority Persistent, Bioaccumulative and Toxic Pollutants (PBT Strategy) was drafted by the USEPA. The PBT Strategy led to the implementation of PBT criteria in several regulational policies. Two main policies that were changed by the PBT strategy were the Toxics Release Inventory (TRI) which required more rigid chemical reporting and the New Chemical Program (NCP) under the Toxics Substances Control Act (TSCA) which required screening for PBTs and PBT properties.

PBTs are a unique classification of chemicals that have and will continue to impact human health and the environment worldwide. The three main attributes of a PBT (persistence, bioaccumulative and toxic) each have a huge role in the risk posed by these compounds.

...
Wikipedia