Handbook of Solvents - George Wypych - ChemTech - Ventech!

20.3 Pregnancy outcome following solvent exposure 1345
Traditionally, a power analysis would be conducted to determine the number of subjects
or in this situation the number of “studies” that need to be added to produce a significant
result. In order to perform a power analysis effect sizes must be calculated from the
summary statistic. The result from this power analysis indicates that one would have to obtain
2 studies with a medium effect size (0.5) to bring this study’s overall effect size
(d=0.095) to a small effect size of 0.2. Similarly, 5 articles with an effect size of d=0.3 are
needed to bring the study’s overall effect size to 0.2. The largest effect size in the spontaneous
abortion analysis was d=0.2. None of the acceptable studies achieved such a large effect
size as 0.5. It may be improbable because one would expect that such results would undoubtedly
have been published. Unfortunately, no statistical test yet exists to precisely determine
such a probability and one must therefore exercise judgment.
This meta-analysis addresses the use of organic solvents in pregnancy. Organic solvent
is a very broad term that includes many classes of chemicals. There may still exist rates
of abortion higher than the value reported with certain groups of solvents. However, a detailed
analysis of classes of solvents is in order to incriminate a particular solvent. Not all of
the studies have examined the same groups of solvents in terms of both extent and range of
solvents as well as frequency and duration of exposure. Hence it would be very difficult to
obtain any clear estimate of risk for a given solvent given the limited number of studies
available.
Conclusion
The meta-analysis examining organic solvent use in pregnancy did not appear to find a positive
association between organic solvent exposure and spontaneous abortions (ORs = 1.25,
confidence interval 0.99 - 1.58). The results from the meta-analysis examining organic solvent
use in the first trimester of pregnancy and major malformations indicate that solvents
are associated with an increased risk for major malformations (ORs = 1.64, confidence interval
1.16 - 2.30). Because of the potential implications of this review to a large number of
women of reproductive age occupationally exposed to organic solvents, it is important to
verify this cumulative risk estimate by a prospective study. Similarly, it is prudent to minimize
women’s exposure to organic solvents by ensuring appropriate ventilation systems
and protective equipment.
Meta-analysis can be a key element for improving individual research efforts and their
reporting in the literature. This is particularly important with regard to an estimate of dose in
occupational studies as better reporting of the quantification of solvent exposure is needed
in the reproductive toxicology literature.
20.3.4 PREGNANCY OUTCOME FOLLOWING GESTATIONAL EXPOSURE
TO ORGANIC SOLVENTS: A PROSPECTIVE CONTROLLED STUDY
[Adapted, by permission, from S. Khattak, G. K-Moghtader, K. McMartin, M. Barrera, D.
Kennedy and G. Koren, JAMA., 281, 1106 (1999) Copyright 1999, American Medical Association]
The Motherisk Program at the Hospital for Sick Children was the first to prospectively evaluate
pregnancy and fetal outcome following maternal occupational exposure to organic solvents
with malformations being the primary outcome of interest. 30
Methods
The study group consisted of all pregnant women occupationally exposed to organic solvents
and counseled between 1987-1996 by the Motherisk Program at the Hospital for Sick
Children. Details concerning the time of exposure to organic solvents were recorded for de-