Each PCB molecule consists of chlorine atoms attached to a double carbon-hydrogen ring (a "biphenyl" ring). There are actually 209 different PCB "congeners", which differ in the number and location of chlorine atoms. It is generally believed that the more highly chlorinated PCBs are more toxic than PCBs with fewer chlorine atoms.
GE-sponsored experiments suggest that, under laboratory conditions, certain bacteria exposed to samples of the riverbed sediments containing high PCB concentrations will partially strip chlorine from the PCB molecules, thereby partially degrading them. The essential question is whether the breakdown of PCBs possible under laboratory conditions is happening, or can be made to happen, in the bottom of the Hudson river.
GE participated in hearings held in 1988-1989 by the NYS Hazardous Waste Facility Siting Board on the feasibility of the state's proposed PCB Clean-up Project. In the course of the hearings, GE strongly opposed the state's proposal, claiming that natural "biodegradation" was an effective alternative to the state's dredging plan. GE claimed that, not only was the dredging unnecessary, but that any disturbance of the riverbottom sediments would disrupt the natural breakdown process.
To support their claims, GE's scientist, John F. Brown, presented data from Hudson River sediments which show its PCB compounds to have a greater abundance of lower chlorinated forms than the original mixtures used at the GE factories in 1977 and earlier. (State of New York Industrial Hazardous Waste Facility Siting Board Hearings in the matter of Applications of the NYS DEC, to dredge PCBs from the Hudson River and to construct and operate a Hazardous Waste Management Facility in the town of Fort Edward, Washington County, NY, TRANSCRIPT OF PROCEEDINGS, 1987).
Flaws in Brown's argument became apparent under cross-examination by the state. It presumes that the original PCB composition in river sediment should be considered nearly identical to the composition of the commercial mixtures GE purchased in the 1960's. However, the original PCB mixtures were subject to extensive chemical and physical processes in the factories, in sewage treatment facilities and in transport before they ever reached the riverbed.
When cross-examined, another GE expert witness, Dr. James Tiedje, admitted his doubt as to the feasibility of GE's proposed biodegradation alternative and the consequent fate of the river: "There is some activity going on there. What we don't know is how significant that will eventually be in removing PCBs from the Hudson". (State of New York Industrial Hazardous Waste Facility Siting Board, TRANSCRIPT OF PROCEEDINGS, 1987).
GE's findings on partial decay of PCBs in the lab are promising in themselves, but their implications for the river are still speculative. The successful lab process requires treating concentrations of PCBs with chemicals and nutrients, then heating these mixtures to temperatures higher than the river ever gets. According to Brian Bush, a state research scientist in the Environmental Health and Toxicology Division of the State Health Department, though PCBs can be broken down successfully in the laboratory, natural decay of PCBs is "hardly detectable in the river". ("Hudson Said Too Cold for PCB Decay", Brian Nearing, Schenectady Gazette Reporter, February 23, 1989).
In New Bedford Harbor, another site of PCB contamination, federal Environmental Protection Agency (EPA) studies evaluating biodegradation found that although natural processes of biodegradation seem to be occurring at this Massachusetts site, these processes are so slow and uncertain that they cannot be considered a reasonable solution to the problem. EPA scientists questioned both the rate of breakdown and the toxicity of the final breakdown products. (EPA Draft Final, Hot Spot Feasibility Study, New Bedford Harbor, July 1989).
In fact, GE's latest proposal reveals their own lack of faith in their "biodegradation without interference" claims. Last year, they announced plans to begin a pilot project involving substantial "interference". Under GE's proposal, steel sediment containment cells with potential for temperature control, addition of nutrients and microbes and cell content mixing, will be placed in the river (letter from Proskauer Rose Goetz and Mendelsohn to Hon. Thomas Monroe, Regional Director, New York State DEC, September 5, 1990). What will this project prove, other than what GE lab experiments have already suggested and GE continues to deny, that saving the river requires substantial human interference?
The federal Environmental Protection Agency (EPA) is currently reconsidering a Superfund clean-up of Hudson River PCB contamination. Under "Superfund", a federal program to clean up hazardous waste, GE could be held responsible for its pollution of the Hudson River, and may have to pay clean-up costs. During their review process the EPA will choose one of several remediation alternatives, including "no-action".
Both DEC and the EPA have previously completed extensive evaluations of the feasibility of dredging contaminated "hot spots" as possible PCB remediation. In three separate reviews their final statements have indicated that dredging would provide substantial environmental benefits with either few or relatively minor adverse impacts.
There are several newly developing technologies, including chemical, biological or thermal treatment, that could be used to treat the PCBs. It is possible that enhanced biodegradation, in a containment facility, could be one of the treatment technologies used.