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Uncertainties in the Relationship between Tibia Lead and Cumulative Blood Lead Index

2008; National Institute of Environmental Health Sciences; Volume: 116; Issue: 3 Linguagem: Inglês

10.1289/ehp.10778

1552-9924

Norm Healey, David R. Chettle, Fiona E. McNeill, David Fleming,

Trace Elements in Health

Vol. 116, No. 3 PerspectivesOpen AccessUncertainties in the Relationship between Tibia Lead and Cumulative Blood Lead Index Norm Healey David R. Chettle and Fiona E. McNeill David E. B. Fleming Norm Healey Search for more papers by this author , David R. Chettle Search for more papers by this author , Fiona E. McNeill Search for more papers by this author , and David E. B. Fleming Search for more papers by this author Published:1 March 2008https://doi.org/10.1289/ehp.10778Cited by:5AboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit Uncertainties in the relationship between bone Pb and cumulative blood lead index (CBLI), including evidence of nonlinearity and differences between the sexes, should be appropriately recognized when setting workplace blood Pb limits to achieve target bone Pb concentrations.Schwartz and Hu (2007) recommended a maximum occupational tibia Pb concentration of 15 μg/g. They stated that, based on the slope of the relationship between tibia Pb and CBLI calculated by Hu et al. (2007), a tibia Pb of 15 μg/g can be avoided by limiting the CBLI to < 200–400 μg-years/dL.Hu et al. (2007) acknowledged the uncertainty in the slope of the relationship between tibia Pb and CBLI. However, over the range of cumulative Pb exposures that would produce a tibia Pb concentration of 15 μg/g, the slope of the relationship between tibia Pb and CBLI may be less than the slope of 0.05 [95% confidence interval (CI), 0.046–0.055] μg/g per μg-years/dL calculated by Hu et al. (2007).Table 1 presents slopes and mean tibia Pb concentrations among subjects of eight published studies. Gerhardsson et al. (1993) reported a slope of 0.022 μg/g per μg-years/dL (no uncertainty reported) and Armstrong et al. (1992) reported a slope of 0.10 (± 0.02) μg/g per μg-years/dL. These represent a greater range of slopes than reported by Hu et al. (2007).Table 1 Various slopes of the relationship between tibia Pb and CBLI, and related mean tibia Pb concentration among study subjects.StudyNo.rSlopeaMean Pb (μg/g tibia bone mineral)Gerhardsson et al. (1993)1000.600.02216.9Erkkilä et al. (1992)910.660.028 ± 0.00321.1Somervaille et al. (1988)790.860.050 ± 0.00331.0Somervaille et al. (1988)880.820.060 ± 0.00532.3Cake (1994)530.700.059 ± 0.00939Fleming et al. (1997)3670.830.056 ± 0.00240.6Hu et al. (1991)120.920.061 ± 0.00846Armstrong et al. (1992)150.870.10 ± 0.0254.8aUnits are μg/g bone mineral per μg-year/dL.These data also suggest that the tibia Pb versus CBLI slope may not be constant, with lower slopes evident for lower tibia Pb and CBLI levels. This trend has been noted previously (Chettle 2005; Fleming et al. 1997). For tibia Pb concentrations of approximately 15 μg/g, a slope of approximately 0.025 μg/g per μg-years/dL seems equally plausible as the slope calculated by Hu et al. (2007).A slope of 0.025 μg/g per μg-years/dL yields an allowable CBLI of 600 μg-years/dL, or an average annual blood Pb concentration of 15 μg/dL for 40 working years. This compares to 5–10 μg/dL for 40 working years associated with Schwartz and Hu’s (2007) recommended CBLI of 200–400 μg-years/dL.These slopes are also based on studies of predominantly male subjects and may not account for differences in Pb toxicokinetics between the sexes (McNeill et al. 2000; Popovic et al. 2005).ReferencesArmstrong R, Chettle DR, Scott MC, Somervaille LJ, Pendlington M. 1992. Repeated measurements of tibia lead concentrations by in vivo X ray fluorescence in occupational exposure. Br J Ind Med 49 (1):14-161733451. Medline, Google ScholarCake KM. 1994. In Vivo X-Ray Fluorescence of Bone Lead in the Study of Human Lead Metabolism [Master’s Thesis]Hamilton, Ontario, CanadaMcMaster University. Google ScholarChettle DR. 2005. Three decades of in vivo x-ray fluorescence of lead in bone. 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Crossref, Medline, Google ScholarHu H, Shih R, Rothenberg S, Schwartz BS. 2007. The epidemiology of lead toxicity in adults: measuring dose and consideration of other methodologic issues. Environ Health Perspect 115:455-46217431499. Link, Google ScholarMcNeill FE, Stokes L, Brito JA, Chettle DR, Kaye WE. 2000. 109Cd K X ray fluorescence measurements of tibial lead content in young adults exposed to lead in early childhood. Occup Environ Med 57(7):465-47110854499. Crossref, Medline, Google ScholarPopovic M, McNeill FE, Chettle DR, Webber CE, Lee CV, Kaye WE. 2005. Impact of occupational exposure on lead levels in women. Environ Health Perspect 113:478-48415811839. Link, Google ScholarSchwartz BS, Hu H. 2007. Adult lead exposure: time for change. Environ Health Perspect 115:451-45417431498. Link, Google ScholarSomervaille LJ, Chettle DR, Scott MC, Tennant DR, McKiernan MJ, Skilbeck Aet al.. 1988. 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CHETTLE D (2011) In vivo applications of X-ray fluorescence in human subjects, Pramana, 10.1007/s12043-011-0038-y, 76:2, (249-259), Online publication date: 1-Feb-2011. Chettle D and McNeill F (2019) Elemental analysis in living human subjects using biomedical devices, Physiological Measurement, 10.1088/1361-6579/ab6019, 40:12, (12TR01) Vol. 116, No. 3 March 2008Metrics About Article Metrics Publication History Originally published1 March 2008Published in print1 March 2008 Financial disclosuresPDF download License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. 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