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

AX6-24
Table AX6-2.8. Effects of Lead on Neuromotor Function in Children
Reference, Study
Location, and Period Study Description Pb Measurement Findings, Interpretation
United States
Dietrich et al. (1993b);
Bhattacharya et al.
(1995); Ris et al.
(2004)
U.S.
Europe
Wasserman et al.
(2000a)
Yugoslavia
Design: Prospective longitudinal. Relationship
between Pb exposure and neuromotor function has
been examined in several studies on the Cincinnati Pb
Study Cohort from 6 to 17 yrs of age. At 6 yrs of age
245 subjects were administered the Bruininks-
Oseretsky Test of Motor Proficiency (BOTMP); at 6-
10 yrs of age subjects were assessed for postural
instability using a microprocessor-based strain gauge
platform system and at 16-17 yrs of age the finemotor
skills of study subjects were assessed with the
grooved pegboard and finger tapping tasks (part of a
comprehensive neuropsychological battery).
Extensive measurement of medical and
sociodemographic factors.
Design: Prospective longitudinal. Birth cohort of
~300-400 infants followed since birth residing in two
towns in Kosovo, Yugoslavia, one group near a
longstanding Pb smelter and battery manufacturing
facility and another in a relatively unexposed location
25 miles away. 283 children at age 54 mos were
administered the Beery Developmental Test of
Visual-Motor Integration (VMI) and the Bruininks-
Oseretsky Test of Motor Proficiency (BOTMP).
Extensive measurement of medical and
sociodemographic factors.
Prenatal (maternal) and
serial postnatal blood Pb
assessments
Prenatal blood Pb 8.3
(SD 3.7) µg/dL
Blood Pb at 2 yrs 17.4 (SD
8.8) µg/dL
Maternal prenatal, umbilical
cord and serial postnatal
blood Pb
Maternal blood Pb in
exposed area 19.9
(SD 7.7) µg/dL,
unexposed area 5.6
(SD 2.0) µg/dL
Umbilical cord blood Pb in
exposed area 22.2
(SD 8.1) µg/dL,
unexposed area 5.5
(SD 3.3) µg/dL
Blood Pb at 2 yrs in exposed
area 35.4 µg/dL, unexposed
area 8.5 µg/dL
Following covariate adjustment, postnatal Pb exposure was
significantly associated with poorer scores on BOTMP
measures of bilateral coordination, visual-motor control,
upper-limb speed and dexterity and the Fine Motor
Composite score. Low-level neonatal blood Pb
concentrations were also significantly associated with poorer
scores on the aforementioned subtests, as well as measures
of visual-motor control. Postnatal Pb exposure was
significantly associated with greater postural instability in 6-
10 yr-old subjects and poorer fine-motor coordination when
examined at 16-17 yrs.
Authors conclude that effects of early Pb exposure extend
into a number of dimensions of neuromotor development.
Following covariate-adjustment, the log avg of serial blood
Pb assessments to 54 mos was associated with lower Fine
Motor Composite and VMI scores. Pb exposure was
unrelated to gross motor performance. With covariate
adjustment, an increase in avg blood Pb from 10 to 20 µg/dL
was associated with a loss of 0.62 and 0.42 points
respectively, in Fine Motor Composite and VMI. Authors
noted that other factors such as indicators of greater
stimulation in the home make a larger contribution to motor
development than Pb.