Abstract:
:K line x-ray fluorescence (KXRF) measurements of bone lead have emerged as a promising new biological marker of internal lead dose in epidemiological studies. Some disagreements exist, however, over the analysis of data at low levels of bone lead concentration. In this study, we performed 30 serial measurements on each of three phantoms containing spiked amounts of lead. Chemical analysis of these phantoms using an inductively coupled plasma mass spectrometer (ICPMS) indicated that the lead concentrations were 0.30, 5.77, and 11.57 micrograms g-1. Analysis of the data was performed using several definitions of a minimum detectable limit (MDL) to recode data below the MDL, and using all of the continuous point estimates of lead concentration in the phantom (including negative estimates). The results demonstrate that the use of MDLs to recode low-level observations reduces the efficiency of the analysis and the ability to distinguish between the phantoms. Retaining all point estimates of KXRF-measured bone lead concentration provides less bias and greater efficiency in comparing the mean or median levels of bone lead of different populations.
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Kim R,Aro A,Rotnitzky A,Amarasiriwardena C,Hu Hdoi
10.1088/0031-9155/40/9/007subject
Has Abstractpub_date
1995-09-01 00:00:00pages
1475-85issue
9eissn
0031-9155issn
1361-6560journal_volume
40pub_type
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