Oct 27, 2013

Introduction to Persistent, Bioaccumulative, Toxic (PBT) Compounds in the Environment

ENN Original news: Global chemical contamination is a worldwide concern affecting every being on earth. Chemical exposure, whether it is through air, water, plants, soil or our modern living environment is unavoidable.  But certain chemicals and compounds having Persistent, Bioaccumulative, Toxic (PBT) characteristics are more dangerous to our environment than others because of their inability to break down easily, are easily transferred throughout all forms of environmental media, and posing risks to human health and the ecosystem due to their toxicity at low concentrations.

Currently, the UN, EPA, and many other countries are working to identify and develop strategies to reduce these risks by inhibiting the transfer of those PBTs that are already present in our environment and preventing and limiting new PBTs from entering the environment either through commerce or waste residual.

The EPA has a list of 16 chemicals and 4 chemical categories for PBTs, which are subject to reporting. The UN has a similar list of which began with a list of twelve Persistent Organic Pollutants (POPs) billed as the 'Dirty Dozen'. Both lists have evolved over time to reflect changing conditions. Although the EU is currently ahead of the US on this issue, amongst all countries involved, much is being done to identify, and consistently regulate the PBT use globally. 

The EPA PBT list identifies the most dangerous chemicals, which were or are used:  pesticides, petroleum derivatives (polyaromatic hydrocarbons [PAHs]), certain metals, PCBs, dioxins/furans, amongst others. These PBTs are found in numerous everyday products and residuals.

A PBT is capable of remaining in the environment in an unchanged form in air, water, soil, or sediment and is expressed in half-lives.  Scientists studying PBTs are also concerned with the Bioconcentration within aquatic systems and Biomagnification within animals through their diets. Scientists will test for toxicity in fish and animals for chronic exposure and its subsequent adverse health effects.

Tools, such as the EPA PBT Profiler have been developed to predict if a substance is PBT.

The results of all of this testing is to protect human health and the environment. When a PBT is identified, it is important to limit its use by finding a substitution unless the manufacturer can demonstrate a very compelling socio-economic benefit that would outweigh the risk.

Read more at the EPA and the UNEP.

Additional support for this article came from Laurie Gneiding of AMEC (laurie.gneiding@amec.com).