Chemistry Reference
In-Depth Information
Placental levels of arsenic were highest in areas with
the highest environmental contamination, and exposed
pregnant women were at higher risk of oxidative dam-
age during pregnancy. Aschengrau
et al
. (1989) inves-
tigated the relationship between community drinking
water quality and spontaneous abortion. Type and
concentration of trace elements were gathered from
routine analyses of public tap water supplies of areas
where the women resided during pregnancy. After
adjustment for potential confounders, an increase in
the frequency of spontaneous abortion was associated
with high levels of arsenic.
In a case-control study of stillbirths, Ihrig
et al
. (1998)
included the assessment of environmental arsenic
exposures and analysis of confounders (race, ethnicity,
maternal age, median income, and parity). There was
a statistically signifi cant increase in the risk of stillbirth
in the group with highest exposure to arsenic. Further
analysis showed that the increase was limited to His-
panic people, possibly because of a genetic impairment
in folate metabolism. However, this study had a small
number of cases in the high exposure group, lacked data
on smoking, and did not consider potential confounding
exposures to other chemicals. As a whole, the studies on
arsenic reproductive effects have been criticized because
they did not adequately measure exposure to arsenic
and other metals and did not evaluate other potential
confounding factors (Golub
et al
., 1998, NRC, 1999).
In the multigenerational experimental study by
Schroeder and Mitchener (1971), female rats continu-
ously exposed to arsenate in drinking water did not
show decreased fertility. Two other studies demon-
strated that reproductive functions (included precoi-
tal interval, mating index, and fertility index) were
not affected in female rats orally exposed to trivalent
arsenic by gavage from 14 days before mating through
gestation (Holson
et al.,
1999; 2000b). Some effects were
demonstrated in female mice exposed to monomethyl
arsonic acid before mating and during pregnancy with
production of fewer litters than normal, but this effect
was attributable mainly to decreased fertility of the
males (Prukop and Savage, 1986). Also, rats treated
with arsenic by daily gavage (before mating and con-
tinuing through gestation) had signifi cantly reduced
fetal body weights and signifi cantly increased skeletal
malformations that the researchers considered to be
consequences of growth retardation.
In mice treated with arsenic acid, there was a signifi -
cant increase in the number of resorptions per litter and
signifi cant decreases in the number of live pups per
litter and mean fetal weight. However, overt maternal
toxicity (including death) was found at the same or lower
doses as those leading to developmental effects (Holson
et al
., 2000a; Nemec
et al
., 1998; Stump
et al
., 1999).
3.8 Platinum
After the introduction of automobile catalytic con-
verters, platinum, palladium, and rhodium have been
emitted with exhaust fumes, and increasing levels have
been found in different environmental matrices such as
road dusts, soils along heavily frequented roads, and
sediments of urban rivers. Compared with other heavy
metals, the biological availability of platinum, palla-
dium, and rhodium in some experimental studies on
road dusts ranged between that of cadmium and lead
(Zimmerman and Sures, 2004). As stated by the same
researchers, chronic effects on the biosphere cannot
be excluded because of (1) their cumulative increase
in the environment, (2) their unexpected high bio-
logical availability and bioaccumulation, and (3) their
unknown toxicological and ecotoxicological potential.
Many clinical cases of pregnant patients affected by
cancer treated by chemotherapy with platinum com-
plexes have been reported in the obstetrical and gyne-
cological scientifi c literature, with births at term and
normal infants.
Male-mediated effects on Sprague-Dawley rats treated
with a single intraperitoneal injection of cis-platinum
were studied by Kinkead
et al
. (1992). Signifi cant pre-
implantation loss was seen in the treated groups. The
weights of the fetuses were also signifi cantly lower
than those of the control group. These results sug-
gested that cis-platinum has a deleterious effect on the
female reproductive system.
Morphological and functional effects on rat ova-
ries (Borovskaja
et al
., 2004), embryotoxic effects in rat
(Chug
et al
., 1998), embryo lethality, and teratogenic
effects (Ognio
et al
., 2003) have been demonstrated
after exposure to platinum complexes.
3.9 Mixed Metal Exposure
For humans, there are few recent studies on mixed
exposures to metals. Nordstrom and coworkers
(1978a,b; 1979a) reported on the frequency of spontane-
ous abortions and birth weights of children born near a
copper smelter in northern Sweden that emitted lead,
arsenic compounds, and sulfur dioxide. The compari-
son of women working at the smelter with women not
occupationally exposed suggested increased frequen-
cies of abortions and depressed birth weights related
to exposure. Because of the low levels of exposure in
the nonoccupationally exposed population and the
inclusion of smelter workers in the regional analysis,
great care must be taken in interpreting the results.
Similar results relating metal exposure to spontane-
ous abortions have been reported by Hemminki and
coworkers (1980). Hospital records, union memberships,
