Air Quality Criteria for Lead Volume II of II - (NEPIS)(EPA) - US ...

AX4-11
Table AX4-4 (cont’d). Bone Lead Measurements in Environmentally-Exposed Subjects
Reference, Study
Location, and Period Study Description
United States (cont’d)
McNeill et al. (2000)
Idaho and Washington
1994
Mexico
Farias et al. (1998)
Mexico City and suburbs
1995-96
PbB = blood lead.
To determine if high Pb exposure in
childhood persisted until adulthood.
262 exposed subjects and 268 age and
sex matched controls aged 19 – 29 yr.
Tibia bone Pb, cumulative PbB index.
Inverse weighted group mean data,
linear regressions.
Examined the relation of blood and
tibia bone Pb levels to Pb
determinants in 100 adolescents aged
11 to 21 yr. LOWESS smoothing,
multivariate regressions.
Lead Measurement (SD or range)
PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation
Group inverse weighted mean (SEM).
Males: Exposed 4.54 (0.31); controls 0.03 (0.31) µg
Pb/g bone mineral.
Females: Exposed 5.61 (0.43); controls 1.67 (0.43)
µg Pb/g bone mineral.
Females (n = 62): PbB 6.4 (±3.2), tibia 5.5(±8.6).
Males (n = 36): PbB 9.1 (±5.5), tibia 3.8 (±5.5).
25 subjects had bone Pb < 0.
Bone Pb accounted for 4.1% of variation in PbB.
Increase in bone Pb of 21.6 µg/g was associated with
an increase in PbB of 1.2 µg/dL.
Lead from exposure in early childhood had
persisted in the bone matrix until adulthood.
Bone Pb significantly correlated with age for
exposed groups. No significant correlation in
regressions for control groups with age.
Exposed subjects had group bone Pb levels
significantly higher (p < 0.005) than control
subjects in 7 of 11 age groups. Exposed
subjects had increased current PbB
concentrations that correlated significantly
with bone Pb values. Incorporation rate of Pb
into bone 0.039 (0.003) (Fg Pb/g bone
mineral)/ µg/dL yr).
Predictors of bone Pb included higher traffic
density near the home, mother's smoking
history, and time spent outdoors. Predictors
of log-transformed PbB included bone Pb
levels, male sex, use of Pb-glazed ceramics,
and living in Mexico City. Bone Pb
accumulated over time constitutes a moderate
source of circulating Pb during adolescence