INTRODUCTION
Reproduction is nature's design to propagate the race. Sexual urge is a great biological need to have conception. The world today is divided into developing countries with excess fertility and most developed countries with very low fertility. Fertility needs to be controlled so that population remains stable. The declining fertility in developed countries is as much a problem as excess fertility in developing countries. It needs to be investigated in a scientific way if the decline in fertility is real or is it apparent. There is no consensus about declining fertility. It should be appreciated that there is a difference between voluntary childlessness and infertility. Many professionals want to delay pregnancy to achieve their career goals and try for conception when the woman is 35 years plus. Female fertility is known to decline with age. Delay in marriage due to social or economic reasons and further delay in childbearing to build academic or professional career gives an impression that fertility is declining. More couples seek help for infertility because of the delay in childbearing. The aging process makes conception more difficult. Modern life style, more women joining work force, environmental pollutants and stress of modern life has modified the reproductive behavior. Bhatt (2000) has reviewed the literature on impact of environmental pollutants on reproductive behavior (Table 1.1).2
Zoologists were the first to notice a change in the reproductive behavior in animals. Many of the pollutants have estrogenic effect. Theodora Colborn, zoologist from USA, suggested the term “Endocrine Disruptors” for substances that interfere with or mimic the action of hormones. Dioxin is known to damage reproductive system of the offspring resulting in decreased sperm count and altered mating behavior. Dioxin is also implicated as a cause for endometriosis. The feminization of male gulls and terns along the pacific coast of the US had been reported in 1987. Male river fish living downstream of a pulp mill were found in 1991 to have smaller than normal gonads and absence of secondary sex characters (WRI report).
Recently, accidental spillage of chemicals (DDT, Sulphuric acid and Dicofol) in 1980 into a small area in Florida wetlands, the alligator population of Lake Apopka began to decline as females exhibited excessive estradiol concentration and males abnormally stunted sex organs (Bhatt 2000). Most of the chemicals in insecticides, fungicides and pesticides contain estrogen like substances, which affect the male sex organs. World Resources Institute report (1995) shows following effect of chemical pollutants on wild life:
- Thyroid dysfunction in birds and fish.
- Decreased fertility in birds, fish, shellfish and mammals.
- Decreased hatching success in birds, turtles and fish.
- Feminization of male fish, birds and mammals.
- Masculinization of female fish, birds and mammals.
Animal studies have shown definite correlation between exposure to environmental pollutants and infertility. However, it is not clear if results of animal studies can be extrapolated to human beings.
The modern life style, fast food habits, stress at work place, more women joining workforce maybe responsible for delay in conception or frank infertility. The following factors need consideration.
- Is the human sperm count declining?
- Is the incidence of polycystic ovaries and endometriosis on the rise over the years?
- Is erectile dysfunction incidence on the increase?
IS THE SPERM COUNT DECLINING?
The estrogen like substances in many chemicals does have impact in sperm count and sperm function. Auger (1995), a French scientist found a true decline in sperm quality in 20 years. Auger and his colleagues analyzed the first ejaculate donated at sperm bank between 1973 to 1992. The study showed that sperm concentration decreased by 2.1 percent per year. Shakkebaek (1994) after meta-analysis of 61 worldwide studies reported seminal volume and sperm concentration reduced by around 50 percent over the past 50 years Richard Sherin (1996) expert of in vitro fertilization wrote in the editorial in New England Journal of medicine.” Despite the declining sperm count reported by French scientists, there is little evidence to show that male fertility is declining. In the United States, trends in infertility have been assessed at the National Center for Health Statistics in National survey of Family Growth (1994). It shows that rates of infertility remained constant during the past three decades (8 to 11 percent) and male infertility accounted for approximately one third of the cases.
Recently, doubts are raised that use of cell phones and computers may reduce sperm count and motility, Dr Imre Feges from University of Szeged in Hungary presented a 4paper at the International conference of fertility experts in Berlin in March, 2005. He suggested that.” Prolonged use of cell phones may have a negative effect on spermatogenesis and male fertility due to radiation emitted by mobile phones. Even when the cell phone is in a standby mode, it can cause damage. There was 30 percent reduction in sperm count who carried mobile phone with them most of the time.” Men who carry mobile phone in a belt holster or trouser pocket are thought to be at highest risk In contrast, Lawrence Challis(2005). Emeritus professor of physics at Nottingham University says that though there is a theoretical risk of reduced sperm count, there was too little research to draw conclusions. There are inconclusive reports of reduction in sperm count in person using Laptop nearer to genital organs.
In 1995, British Government instructed the Medical Research Council (MRC) to investigate the risk of estrogenic chemicals in the environment. The MRC reported that, there is no proof of any causal link between estrogenic chemical pollution and reduced human fertility. International collaborative study is to be launched to find sperm concentrations in volunteers from Britain, France and Scandinavia. The report will clarify if there is a decline in sperm count. This is now where the sperm saga has reached, a saga of logjam, which will only be unlocked when investigations give fresh data on the following points:
- How many estrogenic chemicals we are exposed to?
- What level of exposure to these chemicals can induce estrogenic effect in animals reproductive organs?
- What is our blood level and body burden of these chemicals?
World Health Organization has surmised that there is reduction in sperm count but it is still above the count needed for conception. Therefore, even though there is reduction in sperm count, it cannot be proved to be the cause for infertility.
Environmental Factors and Infertility
Chemical pollution is on the increase all over the world. Moreover, the number of women working in chemical factories 5is increasing. Heavy metals in industries may alter reproductive behavior. Lead is mainly used in printing, painting, battery and smeltering industries. Lead affects male gonads, causes chromosomal alterations and abnormalities in sperm count (Stofen).
POLYCYSTIC OVARY SYNDROME AND ENDOMETRIOSIS–IS IT ON THE INCREASE?
Diabetes and obesity are on the increase due to fast food habits and sedentary life style. It is considered as an important etiological factor for Polycystic Ovaries, which result in anovulation and infertility. Exposure to dioxin maybe responsible for endometriosis, which is a known etiological factor for infertility. Endometriosis is diagnosed more frequently. One is not sure if it is due to better diagnostic tools or is it real.
ERECTILE DYSFUNCTION
The incidence of erectile dysfunction is on the increase in professional men because of stress, over use of alcohol, tobacco and over work. Incidence of anxiety and depression is on the increase and hence the use of tranquilizers and anti-depression drugs is on the increase. National Institute of Health in United States of America has reported that about 30 million Americans are suffering from erectile dysfunction. There is no nationwide study about incidence of erectile dysfunction in India but recent survey by India Today (February, 2005) showed that one out of every ten males in India is developing impotence. Some of the drugs used for treating diabetes, hypertension, depression, and anxiety are known to cause erectile dysfunction. When both the spouses are working, they find difficult to concentrate on sex life. Many couples by choice do not wish to have children. This life style is given the name DINK syndrome (Double income, no kids).
In India the number of females is declining because of selective female feticide. However, there is a fear that the Y 6chromosome is getting weaker. Spencer Wells (2005), well-known bio-historian and population geneticist feels that Y-chromosomes are overrated. He further states that Y-chromosomes are less adaptable. It has only 78 genes while X chromosomes have 1000 genes. Recombination process of X chromosome helps it to evolve and adapt. Y chromosome does not recombine, and therefore, it is less adaptable.
CONCLUSIONS
Animal studies have shown the detrimental effect of environmental pollutants on fertility.
Evidence in humans is inconclusive. There are some reports to show that quality of human sperm is declining but there are other reports to show that there is no significant decline in sperm quality. The decline in fertility in developed countries, appears more voluntary than real. Decline in birth rate in developing countries is more due to greater use of contraception. We may have to wait for sometime and see if results of animal studies would be extrapolated in humans.
BIBLIOGRAPHY
- Auger J. Is sperm count declining? N Eng J Med 332; 289; 1995.
- Bhatt RV. Environmental influence on reproductive health. International J Obst Gyn 2000; 70; 69.
- Imre Feges. Paper presented at International conference on Fertility in Berlin. March, 2005.
- Lawrence Challis. Participant in discussion on paper by Imre Feges in Berlin
- National Survey of Family Growth (NSFG) USA US publication 1994; 62.
- Medical Research Council Report (UK), Richard Sharpe Report. 1995; 45.
- Skakkeback S. Quality of sperms. Br Med 1994; 305;609.
- Spencer Wells. Talk with Narayani Ganesh. Reported in The Times of India, April 16, 2005.
- Stofen D. Less known papers on Lead. Proceedings on Int. National symposium on Environmental Health, 1972; 473.
- World Resource Inst Report.(WRI Report). Threats from environmental estrogens. Washington. 1995.
- WHO Report. Editorial in Br Med J 1992; 305; 609.