Male reproductive health

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Testicular dysgenesis syndrome (TDS) – deteriorating male reproductive health

Testicular dysgenesis syndrome (TDS) is used to describe male sexual disorders that may be apparent at birth or show up in adulthood. They are thought to be linked to abnormal events that occur when baby boys are developing in-utero.  These disorders affect a surprisingly large number of men.

The disorders evident at birth include cryptorchidism where one or both testicles do not descend into the scrotum and hypospadia where the urethral opening is wrongly located on the penis. In many cases both of these disorders require surgical correction.  In adulthood, low sperm counts/infertility and testicular cancer are also becoming increasingly common in young men. These 4 disorders are considered to be interconnected in many cases, and baby boys with undescended testes are at greater risk of having low sperm counts and developing testicular cancer.

It is generally thought that abnormal development of the cells in the testicles, plus interference with sex hormones, eg testosterone (the male hormone), are probably the cause.  Genetic, lifestyle and environmental factors may play a part, but for testicular cancer the increase over the last 40 years is such that it must be something in the environment or lifestyle factors that are largely to blame, because genes in a population do not change that quickly.  It’s a hypothesis that is the cause of much concern within the medical community and and has been written about extensively in many respected journals, including The British Medical Journal and The Lancet.

Several man-made chemicals have the ability to block the male hormone.  In animals these chemicals can give rise to undescended testicles, malformation of the penis and low sperm counts.  Therefore, there is concern that these chemicals may have similar effects in humans.  Concerns are increased because it is known that many of these chemicals can act together to cause effects even when each is below a concentration to cause an effect on its own.   However, it is very difficult to prove or disprove whether these chemicals are actually causing the demasculinising effects that are now being seen in men.   Nevertheless, many scientists are now raising their concerns about the action of these endocrine or hormone disrupting chemicals, which can block the male hormone testosterone.   

The concern for human health is underlined by findings in wildlife.  Male fish, amphibians, reptiles, birds and mammals have all been harmed by chemicals in the environment, and feminisation is widespread.  See CHEM Trust’s December 2008 report entitled “Effects of Pollutants on the Reproductive Health of Male Vertebrate Wildlife - Males Under Threat” 

The seriousness of the male reproductive health problem is highlighted by recent health statistics from Denmark where trends in reproductive diseases, including testicular cancer, are showing a worrying increase.

• Almost 1% of mostly young men are treated for testicular cancer.

• 5.6% of schoolboys have undescended testicles.

• Almost 1% have abnormalities of the penis when they are born. 

• Furthermore over 40% of young adult men have subnormal sperm counts.

Several recent studies have shown associations between prenatal or postnatal exposure to certain pesticides or phthalates and effects on reproductive disorders or male hormones.

View publications on male reproductive health

References

Møller H, Skakkebaek NE (1999). Risk of testicular cancer in subfertile
men: case-control study. BMJ. Feb 27;318(7183):559-62.
http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=10037628

Skakkebaek NE, Rajpert-De Meyts E, Main KM (2001). Testicular
dysgenesis syndrome: an increasingly common developmental disorder with
environmental aspects. Hum Reprod. May;16(5):972-8.

Boisen KA, Kaleva M, Main KM, Virtanen HE, Haavisto AM, Schmidt IM,
Chellakooty M, Damgaard IN, Mau C, Reunanen M, Skakkebaek NE, Toppari J
(2004). Difference in prevalence of congenital cryptorchidism in infants
between two Nordic countries. Lancet. Apr 17;363(9417):1264-9.

Sharpe RM, Irvine DS (2004). How strong is the evidence of a link
between environmental chemicals and adverse effects on human
reproductive health? BMJ. Feb 21;328(7437):447-51. 
http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=14976101

Joensen UN, Jorgensen N, Skakkebaek NE (2007). Testicular dysgenesis
syndrome and carcinoma in situ of the testes. Nat Clin Pract Urol.
Aug;4(8):402-3. Epub 2007 Jul 10.

Skakkebaek NE, Rajpert-De Meyts E, Jorgensen N, Main KM, Leffers H,
Andersson AM, Juul A, Jensen TK, Toppari J (2007).  Testicular cancer
trends as 'whistle blowers' of testicular developmental problems in
populations. Int J Androl. Aug;30(4):198-205.