Environmental Engineering Reference
In-Depth Information
Table 2.8
Blood Lead Levels (BLLs) in Different Population Groups in the U.S.
Period
1976-1980
1988-1991
Geometric mean
(
95 Percentile
(
Geometric mean
(
95 Percentile
(
Population group
µ
g/dL)
µ
g/dL)
µ
g/dL)
µ
g/dL)
All persons
12.8
25.0
2.8
9.4
Males
15.0
27.0
3.7
10.9
Females
11.1
20.0
2.1
7.4
Children ages 1-5
15.0
28.0
3.6
12.2
Source:
Data extracted from Pirkle, J.A. et al.,
JAMA
, 272, 284, 1994.
exposure, BLLs rise rapidly, and, as a consequence, are sensitive indicators
of recent absorption. Blood lead represents only about 1% of the total body
burden, with most lead stored in bones.
Blood lead levels are widely used to assess human exposure because
they are a sensitive indicator of exposures that have been correlated with
various health endpoints. Population BLL data for the U.S. has been collected
and assessed for the periods 1976 to 1980 and 1988 to 1991 by the National
Health and Nutrition Examination Survey (NHANES), a large-scale study
periodically conducted by the National Center for Health Statistics of the
Centers for Disease Control (CDC). Geometric mean BLLs for different pop-
relatively high BLLs present in all population groups in the period 1976 to
1980 (average BLLs of circa 13
g/deciliter [dL]), and the sharp decline in
BLLs over the following decade. This decline was presumably due to the
phase-down in use of leaded gasoline and other limitations on lead use.
During the late 1970s, approximately 5% of the population had BLLs >25
µ
µ
g/dL, with higher concentrations in males than females. Children in the
age group 1 to 5 years had BLLs in the same range as adult males.
Children in the age range of 1 to 5 years are at particular risk of being
adversely affected by lead because their brains are not fully developed (see
Health effects
below). Consequently, lead contamination of residences and
subsequent exposures has become a major children's health issue.
The prevalence of elevated BLLs in selected populations of children in
evident that approximately 9% of U.S. children ages 1 to 5 had BLLs that
were
g/dL, the CDC level of concern. Highest prevalence levels for
elevated BLLs were found in children ages 1 to 2, and non-Hispanic black
children. In the latter case, black children had BLLs twice as high as white
and Mexican-American children. The increased risk for elevated BLLs
among black children in the U.S. has been reported in a number of studies.
This racial disparity may be due to a variety of factors. Studies indicate
that the major source of environmental lead exposure for black children is
the indoor environment, whereas the outdoor environment is the major
source for white children. Though painted surfaces in white children's homes
≥
10
µ
