Doctors and scientists are almost certainly missing evidence that adverse environmental factors may be responsible for an increase in a range of problems in male reproductive health, according to a leading Danish fertility expert.
Professor Neils Skakkebaek told the European Society of Human Reproduction and Embryology annual meeting at Lausanne today that rising testicular cancer incidence, poor semen quality, high frequency of undescended testicles and hypospadias (an abnormality of the penis) may all be symptoms of a single underlying entity which he has now named TDS - Testicular Dysgenesis Syndrome.
He said that the different ages at which the various conditions present in boys and men, coupled with the fact that medicine is highly specialized, means that these reproductive problems are being looked at in isolation by specialists as varied as urologists, andrologists, oncologists and pediatric endocrinologists.
Professor Skakkebaek, who is a professor at Copenhagen University Hospital, Rigshospitalet, said: "There is evidence that male reproductive function seems to have deteriorated considerably during the past 4 to 5 decades.
"For example, recent figures in Denmark show that reproductive diseases, including testicular cancer, are still increasing. Nearly 1 in 100 (mostly young) men are now treated for testicular cancer, over 5% of schoolboys have undescended testicles, nearly 1 in 100 have penile abnormalities at birth and over 40% have subnormal sperm counts.
"There are also concerns about a low and decreasing birth rate in many industrialized countries, where up to 5% of children are born using artificial reproductive techniques.
"TDS may be caused by genetic or environmental factors or a combination of both. But there is growing evidence from clinical observation of individual patients and from larger epidemiological studies that there is a synchronized increase between countries in male reproductive problems such as testicular cancer, genital abnormalities, reduced semen quality and subfertility.
"In Finland, for example, the rates of testis cancer, undescended testis and hypospadias are lower than among Danish men. But Danish men have poorer semen quality."
He said that the association of male reproductive problems was probably not coincidental but reflected the existence of a common underlying cause resulting in maldeveloped testes.
"Biological and epidemiological studies leave little doubt that TDS can be a result of disruption in embryonic programming and the development of the sex organs in the fetus," he added. "As the rise in the incidence of the various symptoms of TDS has occurred rapidly over few generations, we must consider that adverse environmental factors such as hormone disrupters, probably acting on a genetic susceptibility, could be to blame."
He urged that future epidemiological studies on trends in male reproductive health should not focus on one symptom alone, but take all aspects of TDS into account, otherwise vital biological information may be lost.
[Contact: Margaret Willson]