Editor’s Note: This is the fifth installment in a series of posts looking into some of the the chemical pollutants that have contaminated Puget Sound’s fish and wildlife and pose one of the greatest threats to their survival. This is part one of a two-part series that examines polychlorinated biphenyls (PCBs), which are still polluting people and the environment despite being banned over 30 years ago.
This post was written by Dr. Fran Solomon, an environmental biologist who teaches courses and gives seminars for university students, environmental and health care professionals, and the general public about toxic chemicals and how they affect human health and the aquatic environment.
When I served as an environmental scientist for the Washington Department of Ecology in the 1990s, one of my responsibilities was to inspect businesses and industries on the shores of Puget Sound for compliance with environmental regulations. Before embarking on this part of my job, I was required to undergo a thorough medical checkup including analysis of toxic chemicals in my blood. I was surprised to find out that low levels of polychlorinated biphenyls (PCBs) were present. The nonflammability, heat resistance, and insulating properties of these manufactured chemicals made them useful in the electrical and plastics industries from the late 1920s until the late 1970s (1). However, I had never worked in these industries. Furthermore, PCBs had been banned in the U.S. 12 years before my checkup.
So what were PCBs doing in my blood? They were present because they are persistent toxic chemicals. They hang around for a long time and accumulate in the tissues of organisms, especially the fatty tissues. Their ability to biomagnify in food chains means that each predator will accumulate higher levels of PCBs than were present in its prey. Top predators such as orca whales, other large marine mammals, birds of prey such as ospreys and bald eagles, and humans will have the highest levels of PCBs in their bodies (1,2).
My exposure was likely through the food chain, when I ate fish, meat, and dairy products contaminated with the chemicals. Just like my exposure through the food chain, Puget Sound’s wildlife is similarly exposed to PCBs in their food. Puget Sound resident orca whales have the highest PCBs levels of any whales on Earth. This is because they are at the top of the food chain and eat Chinook salmon that have accumulated PCBs from their prey (3).
Because they are so persistent, more than 30 years after bans in the U.S. and many other countries, PCBs continue to be found in soil, sediments, fish, wildlife, and most people including people living thousands of miles from the sources of these chemicals. Wind currents transport PCBs long distances, where they then settle out in lakes, streams, rivers, and oceans, and make their way up the food chain. The Inuits, who inhabit northern Canada and Baffin Island, eat the meat and blubber of large marine mammals and have the highest PCBs levels of any people in the world (1,4).
PCBs in Puget Sound
For more than 20 years, the Washington Department of Fish and Wildlife (WDFW) has been sampling Puget Sound fish for the presence of PCBs and other toxic chemicals. Every two years, WDFW biologists sample 120 English sole at each of 10 locations in Puget Sound. PCBs have the ability to glom onto sediments, exposing the animals that live there. Because English sole feed in the sediments at the bottom of Puget Sound, PCBs levels in these fish reflect sediment levels of PCBs. The accumulation of PCBs in sediments and aquatic organisms means that these both can be considered reservoirs of PCBs in Puget Sound.
Sadly, scientists are not finding consistent declines in these chemicals in our local fish. During a recent fish sampling and analysis day, WDFW biologist Jim West said “ levels of PCBs in English sole and other Puget Sound fish species have remained constant during the past 20 years for most locations, neither increasing nor decreasing” (2).
Sediments that are contaminated can be cleaned up by removing the sediments or capping them with clean sediments. There have been successful sediment cleanup projects in Puget Sound. For example, PAHs, another class of contaminants, are now lower in the sediments of Sinclair Inlet adjacent to the Puget Sound Naval Shipyard and lower in Eagle Harbor on Bainbridge Island than they were 20 years ago. This has resulted in a reduction of contaminant-related disease in English sole from Sinclair Inlet and Eagle Harbor (2,5).
But cleanups are expensive. The most cost-effective approach to reduce exposure of fish and humans to toxic chemicals is to prevent discharge of such chemicals at the source. Unfortunately, it is too late to do this for PCBs. As Jim West pointed out, “The cat is already out of the bag on PCBs. We need to apply lessons learned from PCBs contamination of sediments and fish to other toxic chemicals in Puget Sound” (2).
1. Wright, David A. and Pamela Welbourn (2002). Environmental Toxicology. Cambridge University Press, Cambridge, U.K.
2. West, Jim, Washington Department of Fish and Wildlife, Interview, May 17, 2011
3. Ross,, P.S., G.M. Ellis, M.G. Ikonomou, L.G. Barrett-Lennard, and R.F. Addison (2000). “High PCB concentrations in free-ranging Pacific killer whales, Orcinus orca: effects of age, sex and dietary preference. Marine Pollution Bulletin 40: 504-515.
4. Colburn, Theo, Dianne Dumanoski, and John Peterson Myers (1997). Our Stolen Future, Penguin Books, New York, N.Y.
5. Myers, M.S., B.F. Anulacion, B.L. French, W.L. Reichert, C.A. Laetz, J.Bozitis, O.P. Olson, S. Sol, and T.K. Collier (2008). “Improved flatfish health following remediation of a PAH_contaminated site in Eagle Harbor, Washington.” Aquatic Toxicology 88: 277-288.