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[Effects on fertility]
2.11 Sperm count [Summary]
Literature survey on effects of endocrine disruptors (except
dioxins) on the male reproductive system, particularly decrease
in sperm count, in 2001 reviewed 6 synchronic studies, 1 cohort
study and 1 nested case-control study. Additional survey for
papers published up to 2004 found 22 reports. The total 30
reports consisted of 15 synchronic studies, 9 case-control
studies, and 6 others. The populations studied were healthy men
in 5 studies (fertile men in 2 studies, regardless of fertility
in 3), outpatients for male infertility in 9, occupationally
exposed populations in 13, directly exposed populations in 2
(DES exposure and yusho in 1 each), other in 1 (mortality and
prevalence statistics). Sources of exposure were pesticides in
13 studies, organochlorines including PCBs in 6, phthalates in
2, styrene in 2, other organic solvents in 2, and others in 5
(DES, polluted air, trihalomethanes, unspecified pollutants,
unspecified factor in 1 each). Association of these factors with
sperm count was significant for at least some of them in 22
studies, insignificant in 6, and inconclusive in 2. Effects in
any form were found in 10 studies out of 13 on pesticides, all
of the 6 on organochlorines and all of 2 on phthalates.
Evaluation methods of effects included, in addition to usual
test parameters (volume and concentration of semen, total sperm
count, sperm motility, normal/abnormal sperm morphology, sperm
viability), sperm motility parameter determined by computerized
automatic sperm analyzer (CASA), frequency of aneuploidy of
sperm nuclear chromosomes detected by FISH, and fragmentation
ratio of sperm nuclear DNA determined by comet assay.
[Purpose]
Deteriorating semen quality, including reduced sperm counts, due
to exposure to endocrine disruptors is of much concern in recent
days. The effect of endocrine disruptors on sperm is
demonstrated in wildlife and confirmed by animal experiments,
but not yet certain on humans. Literature was surveyed in order
to summarize the present status of epidemiologic research on the
effects of suspected endocrine disruptors (except dioxins) on
human sperm.
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