Is the human testis still an organ at risk?

Regional differences in sperm counts and fertility may provide a clue

Although several lines of circumstantial evidence suggest that we may be seeing adverse changes in male reproductive health, it is the possibility that semen quality may have declined that has attracted most attention. In a meta-analysis Carlsen et al examined data from 61 papers published between 1938 and 1991 on the quality of semen in normal men.1 Using linear regression analysis, they identified statistically significant decreases over time in mean ejaculate volume and a fall in sperm concentration from 113x10⁶/ml in 1940 to 66x10⁶/ml in 1990. This report has aroused continuing debate.2 Subsequently, Auger et al published data on 1351 healthy fertile candidates for sperm donation who attended one centre between 1973 and 1992.3 Correcting for sexual abstinence, they observed a significant decline in sperm concentration, the percentage of motile spermatozoa, and the percentage of morphologically normal spermatozoa both as a function of year of birth and age at donation.

Several workers have since …