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.
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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).
Pesticide
container image via Shutterstock.