human sperm count and quality of semen have shown a decline in India in the past decade, report scientists at the Institute of Research in Reproduction ( irr ), Mumbai. They reached the conclusion after studying semen samples of more than 1,500 humans from various parts of the country between 1986 and 1995 ( icmr Bulletin , Vol 27, No 8).

A team of researchers led by E Carlsen at the University Department of Growth and Reproduction, Copenhagen, Denmark, had reported in 1992 that the sperm content and quality in humans are decreasing in the developed countries ( British Medical Journal , Vol 305, No 6854).

Data collected by Carlsen's group between 1938 and 1990 had suggested that the mean sperm concentration has decreased by over 40 per cent from 113x10⁶/ml to 66x10⁶/ml during the period. Most of the data included in the analysis of Carlsen paper came from the European countries such as England, France, Denmark, Scotland and Finland.

Scientists at irr say that while the volume of semen remained unchanged between 1986 and 1995, the number of motile sperms was found to have decreased by over 10 per cent. The number of sperms declined by about 30 per cent during this period in India. The reduction in the number of sperms clearly indicates that there is a definitive trend in the deteriorating semen quality in humans in India.

A study published recently by Rajvi Mehta and T C Anand Kumar at the Reproductive Health Clinic and Research Centre, Bangalore, suggests that the semen quality in humans in Bangalore is declining. The researchers have tried to correlate the declining trend in sperm count and quality with changes in various air pollution indices such as suspended particulate matter ( spm ), sulphur dioxide and lead in the environment ( Current Science , Vol 72, No 9).

Apart from these findings, there are various other theories that have been put forward to explain the decline in the quality and quantity of sperm in humans. One important reason for this decline in western population appears to be an appreciable (three to four times) rise in testicular cancer between 1960 and 1980 in countries such as Denmark, Finland, the uk , Germany, the usa , Japan and Puerto Rico. The increase in testicular cancer has been attributed to the influence of oestrogen on the developing foetus. Researchers have postulated that in the last 50 years, both endogenous and exogenous oestrogen has been on the rise.

The increase in changing diets has led to elevated level of oestrogen inside the body. In fact, some of the livestock such as chicken that were fed anabolic steroids could also have contributed to this increased availability of such chemicals in the body. In addition, increasing amounts of organochlorine compounds that react with other chemicals present within the body also result in oestrogen-like compounds.

Experts say, we now live in an environment that is virtual sea of oestrogens. They feel that it is necessary to systematically collect semen samples from various populations from different parts of the country under uniform conditions, employing internationally acceptable methodology. It is equally important to study the semen quality, especially in urban and rural populations that are continuously exposed to pesticides, for dietary and environmental influences. Such initiative would track down the agents actually responsible for decline in sperm quantity and quality.