Meta-Analysis
on the Adverse Reproductive Effects of Paternal Exposure
to Organic Solvents
Organic
solvents are often found as volatile liquids, belonging
to a structurally diverse group of chemicals that have
a lower molecular weight and dissolve other organic substances
such as lipids and compounds with a high molecular weight.
Their use has become widespread in both home and work
environments. Incidental exposure is more common around
the house, while extensive exposure takes place mainly
in the workplace. Organic solvents are used in a variety
of occupations such as painting, dry-cleaning, printing
and elsewhere in the chemical industry.
Since many employees are
extensively exposed to organic solvents, there is a need
for research in the area of organic solvent exposure. While
a substantial amount of research has been conducted in the
area of maternal exposure to organic solvents, there is
a lack of prospective research on paternal exposure. There
are several studies, however, which have indicated that
paternal exposure to organic solvents may be associated
with an increased risk of spontaneous abortion or fetal
abnormalities. The results of individual studies display
a considerable amount of inconsistency and there is a lack
of concrete information on the actual risk of paternal exposure.
In a meta-analysis conducted
on the effects of paternal exposure to organic solvents,
it was found that although there were significant relationships
between organic solvent and adverse pregnancy outcomes,
conclusions must be drawn with great care. All studies may
not have examined the same classes of organic solvents,
and it is possible that various definitions of organic solvents
resulted in heterogeneity among the studies examined.
It was also established
that some studies may have been subjected to various biases
which arise in men whose wives experience adverse pregnancy
outcomes such as response and recall bias.
A major problem in the studies
examined is that the assessment of organic solvent exposure
is difficult to make, especially when it comes to the exact
severity, duration and time of exposures. Therefore, both
underestimation and overestimation of risk may take place.
Also, some studies separated exposure into high, moderate
and low while others did not. The time of exposure is of
interest because the complete cycle of sperm development
takes 74 days in men. Most studies did not give information
on the specific time of exposures.
In
the design of a prospective study on paternal exposure to
organic solvents, special care must be taken to clearly
define the organic solvents concerned and to eliminate bias.
The level of exposure in terms of severity, duration and
time must also be clearly defined.
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