Biomedical Engineering Reference
In-Depth Information
No infectious agent or other pathogenic factor could be identified. Thus,
it appears that a highly significant toxicological effect on postnatal
growth can be attributed to prenatal methanol exposure at 1800 ppm. The
effects observed were in the absence of appreciable increases in maternal
blood formate levels.
In summary, the Burbacher et al. (1999b, 2004a, b) studies suggest
that methanol exposure may cause reproductive effects, manifested as a
shortened mean gestational period due to pregnancy complications that
precipitated delivery via a C-section, and developmental neurobeha-
vioral effects which may be related to the shortened gestational period.
The effect on gestation length at 200 ppm is questionable, as the
decrease in gestational length was marginally significant and largely
the result of human intervention (C-section). Also, this effect did not
appear to be dose related, the greatest gestational period decrease
having occurred at the lowest (200 ppm) exposure level.
Neurobehavioral function was assessed in 8-9 infants/group during
the first 9 months of life (Burbacher et al., 1999b, 2004a). Although
results in 7/9 tests were negative, two effects were possibly related to
methanol exposure. The visually directed reaching (VDR) test is a
measure of sensorimotor development and assessed the infants' ability
to grasp for a brightly colored object containing an applesauce-
covered nipple. Beginning at 2 weeks after birth, infants were tested
five times/day, 4 days/week. Performance on this test, measured as age
from birth at achievement of test criterion (successful object retrieval on
8/10 consecutive trials over two testing sessions), was reduced in all
treated male infants. Statistical significance was obtained in the
1800 ppm group when males and females were evaluated together
and in the 600 ppm group for males only. However, there were no
significant differences between responses and/or variances among the
dose levels for males and females combined, or for males only. Yet there
was a significant dose-response trend for females only (p
ΒΌ
0.0265).
The extent to which VDR delays were due to a direct effect of methanol
on neurological development or were secondary to the methanol-
induced decrease in gestation length is not clear. Studies of reaching
behavior have shown that early motor development in preterm human
infants without major developmental disorders differs from that of
