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dc.contributor.authorSpence, Lisa Aen_US
dc.contributor.authorAschengrau, Annen_US
dc.contributor.authorGallagher, Lisa Een_US
dc.contributor.authorWebster, Thomas Fen_US
dc.contributor.authorHeeren, Timothy Cen_US
dc.contributor.authorOzonoff, David Men_US
dc.date.accessioned2011-12-29T22:21:56Z
dc.date.available2011-12-29T22:21:56Z
dc.date.copyright2008en_US
dc.date.issued2008-6-2en_US
dc.identifier.citationSpence, Lisa A, Ann Aschengrau, Lisa E Gallagher, Thomas F Webster, Timothy C Heeren, David M Ozonoff. "Evaluation of the Webler-Brown model for estimating tetrachloroethylene exposure from vinyl-lined asbestos-cement pipes" Environmental Health 7:24. (2008)en_US
dc.identifier.issn1476-069Xen_US
dc.identifier.urihttp://hdl.handle.net/2144/2580
dc.description.abstractBACKGROUND: From May 1968 through March 1980, vinyl-lined asbestos-cement (VL/AC) water distribution pipes were installed in New England to avoid taste and odor problems associated with asbestos-cement pipes. The vinyl resin was applied to the inner pipe surface in a solution of tetrachloroethylene (perchloroethylene, PCE). Substantial amounts of PCE remained in the liner and subsequently leached into public drinking water supplies. METHODS: Once aware of the leaching problem and prior to remediation (April-November 1980), Massachusetts regulators collected drinking water samples from VL/AC pipes to determine the extent and severity of the PCE contamination. This study compares newly obtained historical records of PCE concentrations in water samples (n = 88) with concentrations estimated using an exposure model employed in epidemiologic studies on the cancer risk associated with PCE-contaminated drinking water. The exposure model was developed by Webler and Brown to estimate the mass of PCE delivered to subjects' residences. RESULTS: The mean and median measured PCE concentrations in the water samples were 66 and 0.5 μg/L, respectively, and the range extended from non-detectable to 2432 μg/L. The model-generated concentration estimates and water sample concentrations were moderately correlated (Spearman rank correlation coefficient = 0.48, p < 0.0001). Correlations were higher in samples taken at taps and spigots vs. hydrants (ρ = 0.84 vs. 0.34), in areas with simple vs. complex geometry (ρ = 0.51 vs. 0.38), and near pipes installed in 1973–1976 vs. other years (ρ = 0.56 vs. 0.42 for 1968–1972 and 0.37 for 1977–1980). Overall, 24% of the variance in measured PCE concentrations was explained by the model-generated concentration estimates (p < 0.0001). Almost half of the water samples had undetectable concentrations of PCE. Undetectable levels were more common in areas with the earliest installed VL/AC pipes, at the beginning and middle of VL/AC pipes, at hydrants, and in complex pipe configurations. CONCLUSION: PCE concentration estimates generated using the Webler-Brown model were moderately correlated with measured water concentrations. The present analysis suggests that the exposure assessment process used in prior epidemiological studies could be improved with more accurate characterization of water flow. This study illustrates one method of validating an exposure model in an epidemiological study when historical measurements are not available.en_US
dc.description.sponsorshipNational Institute of Environmental Health Sciences (2P42 ES0738)en_US
dc.language.isoenen_US
dc.publisherBioMed Centralen_US
dc.rightsCopyright 2008 Spence et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution 2.0 License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.en_US
dc.rights.urihttp://creativecommons.org/licenses/by/2.0en_US
dc.titleEvaluation of the Webler-Brown Model for Estimating Tetrachloroethylene Exposure from Vinyl-Lined Asbestos-Cement Pipesen_US
dc.typearticleen_US
dc.identifier.doi10.1186/1476-069X-7-24en_US
dc.identifier.pubmedid18518975en_US
dc.identifier.pmcid2432054en_US


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Copyright 2008 Spence et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution 2.0 License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Except where otherwise noted, this item's license is described as Copyright 2008 Spence et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution 2.0 License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.