Persistent Organic Pollutants

Persistent Organic Pollutants (POPs) are chemicals that do not break down easily. In Sitka, POPs were produced at the pulp mill and at WWII sites, but pollutants can also travel via wind and currents.

WWII Naval Operating Base near Sitka

Pollutant Production

POPs are frequently industrial chemicals or pesticides.  Many industrial chemicals are halogenated organic compounds, which have halogen gas elements like chlorine, bromine, fluorine, or iodine bonded to carbon atoms and are very stable in the environment.  These compounds are designed to withstand heat, so they do not breakdown when exposed to sunlight or friction. Pesticides and herbicides are designed to kill biological life, thus are inherently not healthy for human or animal consumption. Because of the permanent and destructive nature of POPs, the effects they have on the natural world can be drastic.

Former Alaska Pulp Mill in Sitka

Environmental Effects

POPs bioaccumulate: they are passed when one organism eats others with contamination. POPs also biomagnify: their contamination increases with an increase in the trophic level. Consequently, pesticides can accumulate in animals and lead to harmful effects, like DDT accumulation in bald eagles, which lead to eggshells breaking and poor hatching rates. Bioaccumulation also disproportionately affects communities that recreationally or subsistence harvest due to their higher consumption rate of potentially contaminated animals. To combat these problems the Stockholm Convention was created.

Stockholm Convention in 2001

The Stockholm Convention

The Stockholm Convention on Persistent Organic Pollutants is a global treaty formed in 2001. The treaty aims to protect human health and the environment from chemicals that remain intact in the environment for long periods and focuses on the restriction and elimination of intentional production of said chemicals. Unfortunately, the United States is one of the few countries that did not ratify the Stockholm Convention.


Advameg, Inc.© 2019.  Chemistry Explained: Organic Halogen Compounds.  [Accessed 11 September 2019].  Available from:

The Convention Overview.  c2008.  Geneva, Switzerland: Stockholm Convention on Persistent Organic Pollutants (POPs); [accessed 9 September 2019].

Stockholm Convention on Persistent Organic Pollutants (POPs).  July 2017.  The 16 New POPs: An introduction to the chemicals added to the Stockholm Convention as Persistent Organic Pollutants by the Conference of the Parties.  Geneva, Switzerland: Stockholm Convention Secretariat United Nations Environment.

Persistent Organic Pollutants: A Global Issue, A Global Response. 2002.  Washington, D.C.: United States Environmental Protection Agency; [Updated December 2009; accessed 11 September 2019].

Wikipedia contributors. Persistent organic pollutants [Internet]. Wikipedia, The Free Encyclopedia; 2019 Feb 24, 18:12 UTC [cited 2019 Sep 12]. Available from:


Sitka Pulp Mill

Stockholm convention

WWII base

Written by Helen Dangel and Muriel Reid


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