Tibia Bone Lead Research Articles

L-Line X Ray Fluorescence of Tibial Lead: Correction and Adjustment of Radiation Risk to ICRP 60

Effective doses E (ICRP 60, 1991) to adults and children from a non-invasive assessment of tibial bone lead by L-Line X ray fluorescence (LXRF) are calculated using published absorbed dose data. E is 1.0 µSv for a 5 year old child and 0.3 µSv for an adult. LXRF effective dose equivalents HE(ICRP 26, 1987) calculated from the same data were previously overestimated about twofold and should have been reported as 1.7 µSv for a 5 year old child and about 0.7 µSv for an adult. Differences between HE and E are largely due to an ICRP recommended reduction of the tissue weighting factor WT for 'bone surface' from 0.03 (ICRP 26) to 0.01 (ICRP 60). The proportion of E from the sum of all the WT weighted equivalent doses to tissues other than red bone marrow ranges from 48% in a 1 year old child to over 99% in adults.

Sequential measurements of bone lead content by L X-ray fluorescence in CaNa2EDTA-treated lead-toxic children.

With the development of L X-ray fluorescence (LXRF) to measure cortical bone lead directly, safely, rapidly, and noninvasively, the present study was undertaken to a) evaluate LXRF as a possible replacement for the CaNa2EDTA test; b) quantify lead in tibial cortical bones of mildly to moderately lead-toxic children before treatment; and c) quantify lead in tibial cortical bones of lead-toxic children sequentially following one to two courses of chelation therapy. The clinical research design was based upon a longitudinal assessment of 59 untreated lead-toxic children. At enrollment, if the blood lead (PbB) was 25 to 55 micrograms/dL and the erythrocyte protoporphyrin (EP) concentration was greater than or equal to 35 micrograms/dL, LXRF measurement of tibial bone lead was carried out. One day later, each child underwent a CaNa2EDTA provocative test. If this test was positive, lead-toxic children were admitted to the hospital for 5 days of CaNa2EDTA therapy. These tests were repeated 6 weeks and 6 months after enrollment. Abatement of lead paint hazards was achieved in most apartments by the time of initial hospital discharge. The LXRF instrument consists of a low energy X-ray generator with a silver anode, a lithium-doped silicon detector, a polarizer of incident photons, and a multichannel X-ray analyzer. Partially polarized photons are directed at the subcutaneous, medial mid-tibial cortical bone. The LXRF spectrum, measured 90 degrees from the incident beam, reveals a peak in the 10.5 KeV region, which represents the lead L alpha line.(ABSTRACT TRUNCATED AT 250 WORDS)

Sequential measurements of bone lead content by L X-ray fluorescence in CaNa2EDTA-treated lead-toxic children.

With the development of L X-ray fluorescence (LXRF) to measure cortical bone lead directly, safely, rapidly, and noninvasively, the present study was undertaken to a) evaluate LXRF as a possible replacement for the CaNa2EDTA test; b) quantify lead in tibial cortical bones of mildly to moderately lead-toxic children before treatment; and c) quantify lead in tibial cortical bones of lead-toxic children sequentially following one to two courses of chelation therapy. The clinical research design was based upon a longitudinal assessment of 59 untreated lead-toxic children. At enrollment, if the blood lead (PbB) was 25 to 55 micrograms/dL and the erythrocyte protoporphyrin (EP) concentration was greater than or equal to 35 micrograms/dL, LXRF measurement of tibial bone lead was carried out. One day later, each child underwent a CaNa2EDTA provocative test. If this test was positive, lead-toxic children were admitted to the hospital for 5 days of CaNa2EDTA therapy. These tests were repeated 6 weeks and 6 months after enrollment. Abatement of lead paint hazards was achieved in most apartments by the time of initial hospital discharge. The LXRF instrument consists of a low energy X-ray generator with a silver anode, a lithium-doped silicon detector, a polarizer of incident photons, and a multichannel X-ray analyzer. Partially polarized photons are directed at the subcutaneous, medial mid-tibial cortical bone. The LXRF spectrum, measured 90 degrees from the incident beam, reveals a peak in the 10.5 KeV region, which represents the lead L alpha line.(ABSTRACT TRUNCATED AT 250 WORDS)