To see if male fertility rates are falling, Scottish researchers are seeking sperm samples to set a baseline of health. Olga Wojtas reports.
"We're all brought up to think we're dangerously fertile, that we only have to look at a member of the opposite sex and pregnancy will ensue," says Stewart Irvine of the Medical Research Council's reproductive biology unit in Edinburgh.
But one in six couples in the United Kingdom has problems conceiving, with at least half the cases stemming from the male partner. And there are growing fears that our pre-millennial lifestyle is making things worse.
The signs are ominous. Male alligators in a lake contaminated by a chemical spillage are found to have abnormal genital development. There are reports that the reproductive health of fish and birds is being severely disrupted because of their exposure to chemicals. And there is increasing evidence suggesting that human male reproductive health could be deteriorating.
Blame is being focused on endocrine disruptors, more popularly known as gender-bender chemicals, which mimic the actions of hormones. The latest scare is that we may be absorbing these chemicals from plastic.
Irvine, a leading researcher in the largest study of its kind into male reproductive health, is phlegmatic. People have assumed that because they can see changes in fish, the same is happening higher up the food chain, he says. But effects on wildlife do not mean inevitable consequences for humans.
"Endocrine disruptors are everywhere. Plastics, for example, contain various chemicals that are endocrine disruptors. But it is far from clear that we are actually exposed to these from our present uses of plastics. There is a lot of speculation, but there is no evidence at present that we do ," he says.
Irvine, in short, is approaching the three-year, Pounds 450,000 study with an open mind. Funded by the Department of Health, the Department of the Environment, Transport and the Regions, and the Health and Safety Executive, it brings together scientists and doctors in the MRC unit and colleagues in public health sciences at Edinburgh University.
The MRC unit has an international reputation for leading-edge work in an under-researched area. For centuries, there has been the medical specialism of gynaecology, devoted to women's reproductive health. But a parallel specialism, andrology, focusing on men, is just emerging.
It is only since the early 1990s that reports have come from various countries to provoke growing scientific concern. These show increased incidence of testicular cancer and growing numbers of boys with undescended testicles or abnormalities of the urethral opening. Some studies suggest that young men have lower sperm counts, while others insist they do not. In Finland, sperm counts seem to be high and the incidence of testicular cancer is low. In Denmark, testicular cancer is ten times more common than in Finland and sperm counts only a third of Finnish men.
"We really don't know where we are," Irvine says. "Can we with confidence say the sperm count is falling? No, we can't. But if you ask, is there evidence that male reproductive health is deteriorating, the answer has to be yes." So far, there are no signs that, even if sperm counts are falling, this is having an impact on fertility. But many scientists believe the apparent problems develop before a boy is born or shortly afterwards.
"If there is a downward trend in reproductive health, and the origins lie in utero, we are now seeing the consequences of 20 to 30 years ago," Irvine says.
"Because of concern that this might be a continuing phenomenon, we have to think ahead 30 years, even if there is no evidence that it is causing us current difficulties."
The Edinburgh team's bid to provide a baseline against which to judge future changes includes a mailshot to 10,000 men aged between 21 and 31, which aims to net at least 800 sperm samples.
Samples must normally be tested within an hour of ejaculation, before the sperm die. But the MRC team has devised a simple chemical cocktail that, when mixed with the ejaculate, will increase this to 24 to 48 hours. The unit sends out one empty tub and one tube of buffer cocktail. The volunteer ejaculates into the empty tube, adds the buffer to his sample, and returns the kit by post, enabling the researchers to get samples from across the country.
"We are interested to see if there are geographical differences within Scotland, from the unsullied Highlands to the ghastly industrial central belt."
Irvine is confident of an adequate response, after publicising the study in the local
media, including a Radio Scotland phone-in. "The feedback we got was largely positive. Younger men are more able to cope with the whole issue of reproductive health and the problems that go with it. I am very aware of the extent of the cultural change going on - the fact I could go on radio and talk about sperm counts and masturbation."
The postal survey includes a questionnaire asking participants about their childhood, employment history, and current health, diet and lifestyle. Because the study aims to investigate the extent to which lifestyle and genetic factors contribute to variations in reproductive health, and semen quality in particular, it will also seek extra information from the participants' mothers and brothers, with the permission of all the parties. Mothers will complete a brief questionnaire about the man's birth and babyhood. The study hopes to distinguish between the impact of genes and lifestyle by comparing twin brothers, who shared a womb and early childhood nutrition, with non-twin brothers, who were fed similarly, and unrelated men.
"You have to collect data for 30 years before you can answer questions robustly. But I do not think we can wait that long," Irvine says. "With this study, we will know clearly for the first time where we are through a random representative sample, which can be followed by another in 20 years. Laying a solid foundation for future research is very important."
'The volunteer ejaculates into the empty tube, adds the buffer to his sample and returns the kit by post, enabling the researchers to get samples from across the country'