| PaulKing 2004-10-26, 7:06 pm |
| Infertility in Men linked to condoms
September 2001
WHAT IS MALE INFERTILITY?
Infertility is the failure of a couple to become pregnant after one year
of regular, unprotected intercourse. In both men and women the fertility
process is complex, and, in many cases, infertility is caused by a
combination of problems in both partners that conspire to prevent
conception.
About 10% to 15% of couples experience some form of infertility, and, in
approximately 40% of these cases, male infertility is the major factor.
Another 40% of infertility problems are caused by abnormalities of the
woman's reproductive system, and the remaining 20% involve couples who
both suffer reproductive difficulties.
Infertility affects one in 25 American men. More than 90% of male
infertility cases are due to low sperm counts, poor sperm quality, or
both. Whether sperm counts are declining overall in industrialized
countries is a controversial issue. [ See Box Declining Male Fertility?]
Declining Male Fertility?
Although there have been reports of declining male fertility in the US and
in Europe, several recent studies have not found a drop in sperm counts
over the past 50 years. A large 2000 study based in Los Angeles, for
example, found virtually no change in sperm count from a study conducted
in the 1950s. Similarly, a Danish study showed no change in sperm quality
in men born between 1950 and 1970.
Some experts suggest that the decline observed in other studies may not
have taken into consideration normal sperm fluctuations that can occur
from year to year and from season to season. Sperm counts also appear to
differ by region.
Temperature and climate, then, may play some role in the differences seen
from country to country and from year to year. In one study, Finland had
the highest measured sperm count in the world, while Britain's was low.
(It should be noted that a more recent study has reported a significant
decline in sperm count in Finnish men between 1981 and 1991.) In another
study, the sperm count in New York City was much higher than that in Los
Angeles.
Note: Many studies are limited, and most rely on data from sperm banks,
which also may not reflect the male population as a whole.
CAUSES
Environmental Assaults
Over exposure to environmental assaults (toxins, chemicals, infections)
can reduce sperm count either by direct effects on testicular function or
on the hormone systems, although the extent of the effect and specific
environmental assaults involved are often controversial.
Exposure to Chemicals. In most cases, avoiding toxic environments can
restore sperm count.
* Pesticides with estrogen-like effects have the strongest evidence for
sperm reduction. Overexposure to estrogen reduces the number of Sertoli
cells (the cells necessary for the initial development of sperm).
Such pesticides include DDT, aldrin, dieldrin, PCPs, dioxins, and furans.
One 1999 study of couples in a fertility clinic reported that when men had
a history of moderate or high on-the-job exposure to pesticides their
fertility rates were lower than men without such exposures. Although tests
of single chemicals containing estrogen have reported little dangers,
other studies indicate that exposure to more than one of these chemicals
may be very harmful.
* Phthalates are chemicals used to soften plastics. Most are harmless, but
the most commonly-used one, called DEHP, may warrant concern, animals
exposed to DEHP had lower than normal sperm counts. In addition, there is
some concern that exposure in pregnant women may affect their children.
* Other chemicals are under investigation. In one 2000 study, workers in a
rubber factory who were chronically exposed to hydrocarbons (ethylbenzene,
*benzene, *toluene, and *xylene) had lower than average sperm count and
sperm qualities. Another 1999 study suggested that men whose work exposes
them to aromatic solvents used in paints, varnishes, glues, and metal
degreasers and other products may be at risk of reduced fertility.
In addition to the effect on fertility, some researchers believe
overexposure to chemicals may also contribute to testicular cancers. In
fact, a 2000 study concluded that there was a link between sperm
abnormalities and testicular cancer.
Among the study participants, men in couples with fertility problems were
more likely to develop testicular cancer. In addition, low semen
concentration, poor sperm motility, and abnormal sperm morphology were all
associated with increased risk for testicular cancer.
* Used in condom manufacture
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