Chemistry Reference
In-Depth Information
Calderon
et al
. (2001) examined the effects of chronic
exposure to lead, arsenic, and undernutrition on the
neuropsychological development of children. After
checking for signifi cant potential confounders, verbal
IQ (
P
< 0.01) decreased with increasing concentrations
of arsenic in urine (AsU). Higher levels of AsU were
related to poorer performance on parameters such as
long-term memory and linguistic abstraction; lower
scores in tests measuring attention were obtained at
increasing values of PbB.
Watanabe
et al
. (2003) reviewed data from an
arsenic-contaminated area in Bangladesh. The authors
concluded that although some human data suggest
possible effects on developmental endpoints, the data
are not suffi cient to determine whether arsenic repre-
sents a serious developmental risk.
A cross-sectional study was carried out to investigate
intellectual function in 201 children aged 10 in a con-
taminated area of Bangladesh (Wasserman
et al.,
2004).
Exposure to arsenic was associated with reduced intel-
lectual function after adjustment for sociodemographic
covariates. Water arsenic levels were associated with
reduced intellectual function in a dose-response man-
ner; children with water As levels >50
of maternal-restraint stress and aluminum exposure on
postnatal development and behavior. The only effect
noted was an increase in the platform quadrant swim
time in treated rats.
5.7 Mixed Metal and Multichemical
Exposure
In addition to an article by Calderon
et al
. (2001) on
neurodevelopmental effects quoted in the preceding
section (5.5 Arsenic), timing of menarche has been inves-
tigated in relation to several ubiquitous environmental
pollutants to which children are commonly exposed
at low levels (i.e., dichlorodiphenyl dichloroethylene
[p,p'-DDE], hexachlorobenzene (HCB), polychlorin-
ated biphenyls (PCBs), mirex, lead, and mercury (Den-
ham
et al.,
2005). The study was conducted on 138 girls,
10-16.9 years of age, and residents in an industrialized
area. Metals and organic compounds were measured
in blood. Mercury levels were at or below background
levels, whereas all lead levels were well below 100
g/
L, the CDC action limit, and PCB levels were consist-
ent with a cumulative, continuing exposure pattern.
The median age at menarche for the total sample was
12.2 years compared with a predicted age in a control
group of 10.5 months later. The analysis of multichemi-
cal exposure among adolescent girls suggests that the
attainment of menarche may be sensitive to relatively
low levels of lead and of certain PCB cogeners.
µ
g/L achieved
signifi cantly lower performance than did children
with water As levels <5.5
µ
g/L. The association was
generally stronger for water arsenic than for urinary
arsenic.
Early postnatal administration of arsenic at suble-
thal doses produced little effect in experimental ani-
mals. Postnatal rats fed 1.5 mg/kg/day of arsenic
trioxide from day 7-21 postpartum did not seem to
differ from controls; 50% mortality occurred at 15 mg/
kg/day (Tamura, 1978). Heywood and Sortwell (1979)
reported high mortality among infant rhesus monkeys
fed 3.75 or 7.5 mg/kg/day arsenic; no growth or devel-
opmental effects were noted among the survivors.
µ
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5.6 Aluminum
No evidences of human developmental effects of
aluminum have been reported, but taking into account
that gastrointestinal absorption of aluminum may be
enhanced by certain dietary constituents, it may be advis-
able to avoid the consumption of high doses of aluminum
during gestation and lactation (Domingo, 1995).
Although knowledge of aluminum toxicity has
improved markedly in recent years, information con-
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