Tuesday, March 23, 2010

Yellow: its worse than you think

Look around you, do you see something that's yellow? Just on my desk I have: post-it notes, a week old McDonald's coffee cup, a crinkled up Shop-Rite bag and all the pages in my lab notebook. I really dislike yellow too, its loud and obnoxious, but regardless, its all around us. But now, I have a new reason to add to my "why I hate yellow list," it contains PCBs.

Ah crap.

Polychlorinated Biphenyls (PCBs) were produced for roughly 50 years in the making of electrical capacitors and industrial lubricants before they were banned in the late 1970s. During that time, over a million tons of PCBs were produced which has lead to widespread environmental contamination. Due to their persistent nature, they act as a legacy contaminant, remaining in the environment at trace levels and being transported globally. Bad stuff huh? PCBs are also one of the most common contaminants we deal with in environmental toxicology because they are toxic and have the ability to become stored within fatty tissue leading to bioaccumulation within organisms and biomagnification within the food chain.

There are 209 congeners, or forms of the compound, that are classified as PCBs. Our scientific knowledge is mainly concerned with those congeners that were manufactured under PCB's trade name of Aroclor since these tend to be the most environmentally relevant. But in 1998, the NY DEC found a relatively unknown congener, PCB 11, enriched within New York Harbor wastewater. The researchers were able to trace this back to a pigment manufacturing plant which made paints. So it was thought these PCBs were either being released from paint production or from paint vapors.

But it turns out, PCB11 is from a specific pigment, called diarylide which is used to make the color yellow. New research in ES&T shows scientists were able to measure PCB11 in newspaper, yellow shopping bags and cereal boxes; pretty much anything except plain white paper. And its not just limited to physical products, PCB11 is ubiquitous. It is in the air, the water, sediment, and organisms. Things just keep looking worse. Within New York Harbor, it was measured at the part per billion (ppb) level which is quite significant. The same applies for the Delaware River, except, there are no pigment manufacturing plants that discharge into this waterway, meaning PCB11 is leaching from our garbage (paper and plastics) and contaminating the water.

PCB11 may prove to be a major obstacle in environmental remediation of areas effected by PCB contamination. For example the Hudson River which was infamously contaminated by two GE plants has just recently begun dredging of PCB-laden sediments. But in lower Hudson NY/NJ harbor, PCB11 remains both high and variable so even the removal of toxic sediment upstream will not make the Hudson PCB-free as long as there are other congeners being constantly released. Still, little is known about PCB11, including its toxicity, so we really don't know what we're setting ourselves up for in the future.

The story ends with some quotes that pretty much encapsulate the whole struggle of environmental toxicology.

"But PCB 11 is also symptomatic of a larger problem. “There are more chemicals being produced and invented than we’re able to analyze in environmental samples. At some point, you have such a mixed soup that the synergistic effect is greater than the individual chemical effect,” says Glenn Milstrey, director of the New York State Department of Environmental Conservation’s Bureau of Water Assessment and Management. “We are addressing legacy pollutants [such as dioxins and PCBs] that were discharged a generation ago,” says Scott Stoner, who heads the department’s Pharmaceuticals Work Group. “Let’s not let today’s emerging contaminants become the legacy pollutants that we leave to our children.”"

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