ABSTRACT
The objective of this study is the estimation of health hazards due to the inhalation of combustion products from accidental mineral oil transformer fires. Calculations of production, dispersion, and subsequent human intake of polychlorinated dibenzofurans (PCDFs) provide us with exposure estimates. PCDFs are believed to be the principal toxic products of the pyrolysis of polychlorinated biphenyls (PCBs) sometimes found as contaminants in transformer mineral oil. Cancer burdens and birth defect hazard indices are estimated from population data and exposure statistics. Monte Carlo-derived variational factors emphasize the statistics of uncertainty in the estimates of risk parameters. Community health issues are addressed and risks are found to be insignificant.
Subject(s)
Fires , Polychlorinated Biphenyls/toxicity , Abnormalities, Drug-Induced , Air Pollutants/analysis , Electronics/instrumentation , Environmental Exposure , Humans , Mineral Oil , Models, Biological , Monte Carlo Method , Neoplasms/chemically induced , Risk FactorsABSTRACT
The Southern California Edison Company (SCE) has instituted a series of control strategies designed to minimize human exposure to polychlorinated biphenyls (PCBs) in electrical equipment used on its system. This paper describes a method of analyzing PCB risks using conservative estimates of human intake of PCBs originating from accidental spills from electrical equipment. The PCB releases from the Edison system were determined. The fate of these releases in soil, air, and water was analyzed to determine how much material reaches human receptors. The air and water pathways were determined to be the most likely candidates for the exposure and risk considerations. PCB intake via ingestion of soil at the spill site was neglected as an exposure pathway. Equipment spills without controls resulted in at the most 2 ng/day human intake of PCBs via the water exposure pathway. This was determined to be negligible in comparison with intake rates used in conjunction with the setting of food tolerance levels based on fish being the main dietary pathway of human exposure. The inhalation exposure of the hundred or so persons in the immediate vicinity of a spill was determined to equal the PCB intakes of the fish-eating subpopulation analyzed by the Food and Drug Administration for 2 ppm tolerance standard in the case of no controls or cleanup. Current cleanup procedures assure that even the persons in the immediate area are well below the intake of the subjects in the fish contamination analysis. All exposures were well below a "virtual safe dose" level estimated in the fish tolerance study.
Subject(s)
Electricity , Environmental Exposure , Polychlorinated Biphenyls , California , Humans , Models, Theoretical , RiskABSTRACT
Blood samples from 738 employees of the Southern California Edison Company were analyzed for PCBs prior to their starting work, as part of a pre-employment medical examination. Blood PCB concentrations of the pre-employment sample had a median of 4 ppb and a mean of 5 +/- 4 ppb. These data are comparable to previously published values for blood PCB concentrations in people without occupational exposure. Plasma PCB concentrations are also sorted by demographic characteristics of the sample (age/race/sex/education). Since the demographic properties of the newly hired employees are reasonably similar to those of the Los Angeles-Long Beach work force, as determined in the 1980 census, we conclude that the low PCB concentrations present in the blood of a sample of new electric utility employees is representative of the regional work force and arise from exposures to PCBs present in the general environment.
Subject(s)
Polychlorinated Biphenyls/blood , Adolescent , Adult , Aged , California , Environmental Exposure , Ethnicity , Female , Humans , Male , Middle Aged , Racial GroupsABSTRACT
Because polychlorinated biphenyls (PCBs) have been implicated as potentially toxic to humans and because the electric utility industry is thought to have significant opportunity for occupational exposure, a study was performed to identify electric utility personnel with the highest PCB exposure potential and to assess their current blood PCB concentrations. For currently employed personnel, a median PCB plasma value of 3 ppb with a mean of 4 +/- 3.65 ppb was found; for a preemployment sample the median was 4 ppb with a mean of 5 +/- 4.25 ppb. PCB concentrations in blood of these personnel are similar to concentrations reported for other populations without occupational exposure. No adverse health impacts would be expected to result from these blood concentrations. These data indicate that no significant occupational exposure has occurred in this utility. This study shows the importance of assessing exposure potential at specific worksites prior to making general exposure or hazard assessments.
