R, PP Reddy, P Reddanna and R Mujtaba. 2002. Role of environmental
estrogens in the deterioration of male factor fertility.
and Sterility 78:1187-1194. [note]
in Epidemiology about this paper
intriguing but limited study suggests that PCBs and phthalate esters
are linked to infertility in men. They report that a series of sperm
parameters were significantly lower in a group of infertile men
than in a control group, and that the infertile men also had higher
levels of contaminants. Unfortunately, the sample sizes
are extremely small and the chemical analysis technique used is
vulnerable to contamination. No firm conclusions can be
drawn from this study. But it surely points toward important areas
did they do? Rozati et al. measured sperm parameters
and contamination levels in 21 infertile men, whose infertility
was established but for which there was no overt and obvious reason.
They compared these measurements to those of 32 control men.
21 infertile men came from an original pool of 557 infertile couples,
screened at a fertility assistance center in Andhra Pradesh, India.
Men from these infertile couples were put through a complete clinical
and case history evaluation, which included semen analysis. These
analyses identified 300 cases in the pool of 557 infertile couples
in which infertility could be attributed to male problems or combined
male/female problems, based on sperm characteristics (e.g., sperm
count < 20 million per ml).
analysis of the 300 cases of male factor infertility revealed 52
men for which no obvious causes of the poor sperm quality were identified
by medical analysis (e.g., hormon disorders, infections, genetic
abnormalities, immunological problems). Also excluded from this
final group were men with a history of systemic diseases, a family
history of infertility/delayed conception, occupational exposure
to reproductive toxicants, tobacco/alcohol consumption, iatrogenic
problems associated with medical treatment... anything that could
be anticipated, a priori, as having possible adverse effects
on the selection process for the control men are not provided, although
the criteria used are. They include: previous evidence of fertility,
no history of tobacco or alcohol consumption, no history of occupational
exposure to reproductive toxicants, no history of medication or
surgery, etc., i.e., the same criteria used above for the
infertile men, except for the history of fertility.
did they find? The sperm of men coming to the fertility
center for assistance was of lower quality than the matched controls.
Ejaculate volume, sperm count, motility, morphology, vitality, osmoregulatory
capacity and chromatin characteristics were all lower.
the infertile men, PCB and phthalate ester levels in semen were
highest in urban fish eaters, followed by: rural fish eaters, urban
vegetarians, rural vegetarians. Fish eaters had higher levels than
non-fish eaters, independent of place of dwelling, and urban living
men had higher levels than rural living men, controlling for diet.
were detected in the semen of the infertile men, but not in that
of the controls.
et al. found significant inverse correlations between PCB
levels and ejaculate volume (p < 0.001), motility (p < 0.05),
vitality (p < 0.001) and osmoregulatory capacity ( p < 0.001).
Higher PCBs were associated with sperm damage ( p < 0.05). There
was no correlation between PCB level and sperm count.
were significantly higher in the infertile men. Abnormal sperm were
more likely at higher phthalate levels (p < 0.001), as was sperm
DNA damage (p < 0.001).
mobile sperm counts were inversely related to both PCB and phthalate
does it mean? This study must be interpreted cautiously
because of the small sample size and, for phthalates, the analytical
are widespread contaminants in virtually every setting. Hence separating
real exposures from laboratory contamination has been problematic.
In 2000 the US CDC published a methodological
breakthrough, measuring the urinary metabolites of phthalates
instead of the parent compound. This allowed them to be certain
they were measuring a compound that had been in a human body, instead
of a contaminant picked up, say, because a plastic had volatilized
phthalates in the lab.
et al. measured phthalate esters directly, instead of metabolites.
Some portion of their measured phthalate levels may therefore be
a result of laboratory contamination, and hence it is not certain
what absolute levels of phthalates were actually in the men. Relative
comparisons between the infertile men and the controls, however,
should still be possible, as long as there was no reason for the
infertile samples to be at greater risk to contamination than the
the sample size is small, the statistical tests are not marginally
significant. This argues that Rotazi et al. are seeing real associations
between impaired semen quality and elevated contamination levels.
past three to four decades has witnessed a tremendous increase
in industrialization in Andhra Pradesh. With 25.72% urbanization
and a literacy rate of 44.09%, the state has 208 industrially
developed areas and estates. Environmental exposure to improperly
disposed industrial effluents from major industries such as
cement and cement products, synthetic drugs and pharmaceuticals,
petrochemicals, plastic industries, heavy electricals, fertilizers,
tobacco, and coal may account for observations of higher xenoestrogen
concentrations and concomitantly lower TMCs [total motile
sperm count] in urban dwellers compared with rural dwellers.
Fertility and Sterility prevents direct links to individual abstracts
of published articles on its website. The journal's home page is:
http://www.elsevier.com/locate/fertilsteril. The abstract and (for
subscribers) full text of this article can be found by browsing
through published issues of the journal. All users must register.