I never thought of this that seriously until Elaine mentioned it on the list yesterday, today, my co-worker Tim was breaking this story in the Baltimore press -AB
Welcome Progress on PCB Decontamination By Tim Zink Distributed 1/10/02 by Blue Ridge Press Words: 838 There may be reason for hope in the effort to contain and minimize the damage to the public health and natural environment inflicted by polychlorinated biphenyls (PCBs). After seven years of experiments on PCB-laden sediments taken from the Inner Harbor in Baltimore, Md., a team of researchers reportedly has identified the first strain of anaerobic bacterium known to break down the strong chlorine bonds within these chemical compounds. According to the Environmental Protection Agency, over 1.5 billion pounds of PCBs were manufactured and sold in the U.S. before the 1976 Toxic Substances Control Act banned domestic production and trade of the compounds. Long prized because of their chemical stability, flame resistance and performance as an insulator, PCBs were used in products ranging from electrical equipment to insecticides. But they are now known to carry significant risks. Limited research into a direct causal link between PCB exposure and cancer in humans has come close to finding a smoking gun, but inconsistencies among studies have made clear proof elusive. Still, the Agency for Toxic Substances and Disease Registry has concluded that, "Based on the evidence of cancer in animals, the Department of Health and Human Services has stated that PCBs may reasonably be anticipated to be carcinogens." Further, a 1996 EPA study found that " � PCBs also have significant ecological and human health effects other than cancer, including neurotoxicity, reproductive and developmental toxicity, immune system suppression, liver damage, skin irritation, and endocrine disruption." Which makes the discovery of a PCB-dechlorinating bacterium a major development, especially since communities nationwide are struggling to assess and reduce the levels of PCB contamination which have befallen them. January 2002 saw the start of the second lawsuit brought by citizens of Anniston, Ala., where a Monsanto Co. factory released immense amounts of PCBs into the air, soil and water over several decades. Recent inquiries allegedly have found that high-ranking officials from Monsanto, the largest U.S. PCB manufacturer, knew PCBs posed serious threats to human health long before production was halted. If proven in court - and if effective cleanup technologies can be developed - the company's chemical division spinoff, Solutia Inc., may be held responsible for shouldering broad cleanup measures and public health studies. Similar stakes may come into play in New York, where federal regulators recently mandated that the General Electric Co. remove PCB-contaminated sediments from stretches of the Hudson River. Debate has continued to flare, however, because in some places the sediments on the river bottom appeared to be naturally lessening the levels of PCB contamination. At other sites in the Hudson, PCB levels in sediments remained constant. Ultimately, a lack of scientific certainty over the best course of cleanup has delayed remediation efforts. For several reasons, the collaborative sediment analysis performed by researchers from the University of Maryland's Biotechnology Institute and the Medical University of South Carolina, funded by the U.S. Office of Naval Research, could mark the beginning of real progress on these fronts. First, while scientists have known that certain aerobic microbes were able to dechlorinate lesser-concentrated PCBs, many within the scientific community were skeptical of ever finding a microbe capable of breaking down the compounds with greater chlorine concentration. Most PCBs commercially produced in the U.S. fall in the latter category. Second, by identifying one of the bacterium necessary for dechlorination of PCBs to occur, the researchers have sped the emergence of practical microbial probes that can guide cleanup activities. Such probes could be used to test sediments on site for the presence of the bacterium necessary to break down PCBs, allowing relatively quick and accurate decision making on cleanup options. In the Hudson River cleanup, for example, microbial probes might allow for on-the-spot testing on whether sediments would break down naturally or require dredging, eliminating complex lab sampling that can consume many months and dollars. Kevin Sowers, the principal researcher from UMBI, considers his team's research a big step toward greater understanding and treatment of PCB contamination. "But a lot more steps need to be taken in the future," he said. "We've found organisms (that cause PCBs to break down) and identified them, next we need to study how exactly they work." There are over 200 known chemical arrangements that PCBs may demonstrate. The recently identified bacterium is especially promising, though, because it broke down the arrangements common in PCBs marketed under the Monsanto Aroclors brand name, which claimed the bulk of the historical U.S. market. Linda Chrisey of the Office of Naval Research characterized the Navy's response to the recent findings as "excited, but cautious." It remains to be proven, she noted, whether causing PCBs to break down also definitively reduces their toxicity, among other concerns. That said, Chrisey also indicated that facilities command personnel at two naval installations with possible PCB contamination issues have offered to contribute sediments for future analyses. The public and its legislators should share this enthusiasm. PCBs have proven themselves to be persistent adversaries to human and ecological health, and progress toward their breakdown should be cheered - and further advanced. Tim Zink is an editor of Blue Ridge Press and a former National Geographic staff member. More of Tim's work at http://www.brces.org
