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Archive for January, 2011

Cambridge Environmental studies health risks from the presence of polychlorinated biphenyls (PCBs) in schools

Tuesday, January 25th, 2011

Cambridge Environmental scientists and engineers are studying risks of indoor air exposure to polychlorinated biphenyls (PCBs) in schools on the health of students and employees.  The fact that most people’s exposures to PCBs stem primarily from what we eat, not what we breathe, has traditionally minimized concern about the latter exposures.

More recently, however, the detection of PCBs in indoor air in schools­­ in Massachusetts, New York, and elsewhere in the U.S. and Europe has caused anxiety in parents and others, and cities and towns are grappling with the substantial costs of addressing these concerns.

The U.S. EPA and others have begun to respond to the health risks posed by this manner of PCB exposure.  The Agency’s preliminary response has been to assess safety by comparing indoor-air PCB exposures to its “reference dose” (RfD); essentially, an acceptable daily intake for PCBs as a mixture.  This reference dose was derived from laboratory-animal tests on a complex mixture of scores of PCBs, in particular, in a former commercial product known as Aroclor 1254.  Importantly, however, the specific patterns of PCB congeners in indoor air in schools and homes differ markedly from those which comprise Aroclor 1254.  For example, one of the PCB congeners that is prominent in indoor air, but not in Aroclor 1254, is 2, 4, 4’-trichlorobiphenyl (PCB 28).  This congener is relatively nontoxic.  Studies of people living in homes constructed with PCBs-containing caulking and other building-sealants reveal increased body-burdens of PCB 28 and several other PCBs, but current assessment methods do not provide a reliable method for characterizing the risks from these exposures.  New methods are urgently needed.

To address this need, we at Cambridge Environmental have begun in-depth reviews of the physical, chemical, biological, physiological, and established or inferred toxicologic properties of each PCB congener of interest.  Working with other scientists in the field, our primary goal is to develop new RfDs (or other metrics) that could be used to assess the potential hazards and risks associated with the PCBs found in air.  Our hope is that these new, realistic metrics will assist school boards, environmental officials, and other community groups in understanding and addressing these issues.