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PCBs in the Housatonic

The Body Scientific

It has been a while since I took organic chemistry, but I remember enough to know that the polychlorinated biphenyl molecules (PCBs) that contaminate our river are ugly, unnatural looking things.

They remind me of eyeglasses — two circles of carbon (the biphenyls) joined by a molecular nosepiece. Chlorine atoms project from the carbons like rhinestone bling (the polychlorinated part).

Nature did not make PCBs and it is not good at destroying them. Chemists made them, starting before the First World War, because they are good insulators and useful as wire coating and in capacitors and other electrical devices. Connecticut banned PCBs in 1976, but some old-school clocks and fluorescent light ballasts may still contain them.

We know these molecules are toxic because of industrial accidents in Japan (1968) and Taiwan (1979). In Japan, rice bran oil became contaminated with PCBs and about 14,000 people used it for cooking. There were nasty symptoms including skin, eye, immune, liver and cognitive defects. These symptoms also occurred in the Taiwan case. Workers in plants making these molecules were getting sick and dying in the 1930s or before, so we probably should have banned PCBs decades before we did.

The problem in the Housatonic stems from long ago manufacture and dumping (then legal) of PCBs by General Electric plants in Pittsfield, Mass. PCBs are oily, dense molecules that sink to the bottom of a river and then leach downstream. The portion of the river that had the highest levels in Massachusetts has been dredged, but there are no plans to scrape PCBs out of the Housatonic in Connecticut.

PCBs contaminate the river sediment where the larvae of invertebrate species live. As the insect larvae hatch, the fish eat them and accumulate their PCBs, especially in body fat. The fish do not seem to be bothered by the levels of PCB they are encountering and since they are usually released, the river produces bigger fish, at least according to anecdote.

It has been 35 years since PCBs were banned, so I was curious about whether the levels of PCBs in the Connecticut portion of the Housatonic were decreasing. I contacted Traci Iott and Susan Peterson of the Connecticut Department of Environmental Protection, who very helpfully sent me the latest (2008) study (available on The Lakeville Journal website, tcextra.com).

Every two years General Electric funds a study (by an independent laboratory) to measure PCBs in river insects and fish. The 2010 data will be available later this year.

These studies are difficult because there are so many variables. There are several species of fish at different sites in the river, and the amount of PCB depends on how fat they are, where they feed, their sex, whether they were stocked and when, and many other factors. PCBs are not uniformly dispersed and tend to accumulate behind dams, which also affects the fish.

The chemical analysis is tedious because fish fillets must be extracted and chemically analyzed, and there are lots of variants of the PCB molecules, depending on the number of chlorines each has.

Nonetheless, the 63-page report, which analyzed mostly brown trout and small mouth bass as well as the caddis flies and other insects on which they feed, seemed well done. The number of fish sampled was arguably small and the statistical analysis is opaque — at least to me.

Fish and insects were taken from four sites — West Cornwall, Bulls Bridge, Lake Lillinonah and Lake Zoar — as they have been since 1984. The downstream sites are slightly less contaminated.

PCB levels were high until about 1992 and then started to decline — but not to zero. Since 2000, the lower levels have been maintained but further decline has been slight.

According to Ms. Iott, the concentration of PCBs in the lower Housatonic is affected by upstream dredging and remediation activities, so low-level leaching from that source could still be affecting us.

There was substantial variation in PCB content from one fish to the next, whether trout or bass. Seven of 40 bass and 15 of 30 brown trout had PCB concentrations exceeding the FDA limit. The average hovered just below the FDA limit (2mg/kg), which may itself be a little arbitrary.

Since there was such a range of concentrations, the average does not mean as much as it might. There is hope because bacteria do slowly degrade these molecules, as do enzymes in your liver, or, presumably, the livers of fish.

Thoreau said that there is no tonic like the Housatonic and that is still true. You can paddle, swim and even fish. It is probably not a good idea to eat the fish yet. We will see what the 2010 report brings.

Richard Kessin, Ph.D., is professor of pathology and cell biology at Columbia University. He and his wife, Galene, live in Norfolk. He can be reached at rhk2@columbia.edu.