PCBs in the Housatonic River

In March 2011 (www.tricornernews.com/content/pcbs-housatonic), I wrote about the chemical nature of polychlorinated biphenyls or PCBs, and why they are still polluting the Housatonic. I intended to revisit the issue sooner, but was distracted by Ebola virus, GMO crops and vaccine controversies. I thought that nature would have taken its course and the PCB levels in our part of the Housatonic River would go down. 

PCBs (www.epa.gov/housatonic/understandingpcbrisks.html) were manufactured by the ton from the 1920s through the 1970s because they make excellent electrical insulators. General Electric dumped many tons into the East Branch of the Housatonic River, which flowed through their large industrial area in Pittsfield, Mass. PCBs were used all over the world and the first problems of factory workers sickened by PCB contamination appeared in the 1930s, but were missed or ignored. There were no organizations like the EPA or OSHA to intervene. PCBs were banned in 1977, but not before many sites were heavily contaminated, including the Housatonic River and New Bedford harbor. 

PCB molecules have a shape and look like a modish set of eyeglasses — two hexagonal rings with a nose bridge; attached to some of those carbons are chlorine atoms, like molecular bling. The number of chlorines on the PCBs in the Housatonic is 5 or 6. If there were only a few, bacteria would have degraded them, but 5 or 6 chlorines stymie the enzymes that degrade PCBs. PCBs in this form are relatively insoluble in water; they drift down the river attached to particles of sediment and have a long life — perhaps hundreds of years, according to one EPA estimate. 

In 2000, GE and the EPA entered into an agreement (www.epa.gov/region1/ge) to clean up their large industrial site in Pittsfield and the first two-mile reach of the river. Many thousands of cubic yards of soil from the banks and a pond were removed and shipped to a landfill and the sites otherwise restored. Beyond the restored section, the flood plain is still contaminated down to Woods Pond in Lenox, about 4 or 5 miles further downstream. This part of the river has many channels and a complex flood plain that will be difficult to excavate and restore. Discussions on remedies, currently underway, are documented on the EPA’s website (www.epa.gov/region1/ge) under the heading “Rest of the River.” GE’s plan involves capping the contaminants in place but residents and environmental organizations argue for excavation and replacement of the soil — a massive operation that will take years. There are no plans in place for removing sediments in the Connecticut portion of the river, as far as I know, but the PCBs coming over the dam at Woods Pond are flowing our way.

PCB levels in the Connecticut part of the Housatonic (www.epa.gov/housatonic/publiceventsandmeetings/20150415/574851.pdf) have been measured every two years since 1980. The previous column was based on 2008 results; this one takes into account results through 2012; the 2014 results will be available soon. The analysis has been funded by GE and measures PCBs in bottom-dwelling insects and in brown trout and small-mouthed bass. Sediments, where benthic insect species feed, were measured at many points down the river to Derby. 

Brown trout and bass have PCBs in their fat tissue throughout the watershed, but downstream fish are less contaminated. Some fish have levels below what the FDA considers a dangerous level — which is 2mg/kg or 2 parts per million. For example, 15 of 30 brown trout had PCB levels in fat tissue that were below the FDA suggested level, which I suspect is somewhat arbitrary. Levels were higher prior to 1992 but then declined and have remained at this lower level with slight variation. Bottom-dwelling insects, such as caddisflies, stoneflies, and Dobsonflies, showed a similar pattern of PCB decline since 1992, with current equilibrium at low but steady levels. 

Sediments appear to me to be a slightly different story. Avatar Environmental, the Pittsfield company in charge of collating these data, wrote a report summarizing measurements since 1980 (www.epa.gov/housatonic/thesite/restofriver/reports/574803.pdf). What struck me was that the sediment PCBs in the lower river, particularly behind the dams at West Cornwall, Bulls Bridge, Lake Lillinonah and Lake Zoar, were often high from 1980 to 1998, but since 1998, they have generally fallen, and some dredged samples are PCB-free. Where did this stuff go? Did it flush out into Long Island Sound? Did bacteria evolve to digest PCBs with 5 or 6 chlorines? Even with some PCBs still coming down the river, these results may not fit the EPA’s depressing 100-year timeline. Let’s hope, but in the meantime, releasing the fish is the best idea.

Richard Kessin, Ph.D., is professor emeritus of pathology and cell biology at Columbia University (rhk2@cumc.columbia.edu). He lives in Norfolk. The author would like to thank Traci Iott of CT DEEP and Kelsey O’Neill, Jim Murphy and Dean Tagliaferro of the EPA for information. Follow the cleanup on EPA’s website or on Facebook.