title: In vivo tibia lead measurements as an index of cumulative exposure in occupationally exposed subjects.
abstract: In vivo tibia lead measurements of 20 non-occupationally exposed and 190 occupationally exposed people drawn from three factories were made using a non-invasive x ray fluorescence technique in which characteristic x rays from lead are excited by gamma rays from a cadmium-109 source. The maximum skin dose to a small region of the shin was 0.45 mSv. The relation between tibia lead and blood lead was weak in workers from one factory (r = 0.11, p greater than 0.6) and among the non-occupationally exposed subjects (r = 0.07, p greater than 0.7); however, a stronger relation was observed in the other two factories (r = 0.45, p less than 0.0001 and r = 0.53, p less than 0.0001). Correlation coefficients between tibia lead and duration of employment were consistently higher at all three factories respectively (r = 0.86, p less than 0.0001; r = 0.61, p less than 0.0001; r = 0.80, p less than 0.0001). A strong relation was observed between tibia lead and a simple, time integrated, blood lead index among workers from the two factories from which blood lead histories were available. The regression equation from two groups of workers (n = 88, 79) did not significantly differ despite different exposure conditions. The correlation coefficient for the combined data set (n = 167) was 0.84 (p less than 0.0001). This shows clearly that tibia lead, measured in vivo by x-ray fluorescence, provides a good indicator of long term exposure to lead as assessed by a cumulative blood lead index.
authors.affiliation: Department of Physics, University of Birmingham, UK.
authors.forename: L J
authors.initials: LJ
authors.lastname: Somervaille
authors.forename: D R
authors.initials: DR
authors.lastname: Chettle
authors.forename: M C
authors.initials: MC
authors.lastname: Scott
authors.forename: D R
authors.initials: DR
authors.lastname: Tennant
authors.forename: M J
authors.initials: MJ
authors.lastname: McKiernan
authors.forename: A
authors.initials: A
authors.lastname: Skilbeck
authors.forename: W N
authors.initials: WN
authors.lastname: Trethowan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001842:Bone and Bones / Q000032:analysis*; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D007854:Lead / Q000032:analysis* / Q000097:blood; D007855:Lead Poisoning / Q000097:blood / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D013052:Spectrometry, X-Ray Emission
chemical_list: D007854:Lead