B eijing is set to play host to the cleanest Olympics in living memory. It appears that on the issue of performance-enhancing drugs, the mousetrap has finally become too sophisticated for even the cleverest mice.

This is the view of Dr Conor O'Brien, the country's leading expert on drugs in sport. "There is well-founded optimism that we will no longer have the spectre of the last 20 years, with almost every sprint champion being exposed as a cheat," said the consultant physician who was medical officer to the Irish team at the 1996 Olympics.

On his return from Atlanta, the Dubliner launched the Irish Anti-Doping Committee of which he was also the inaugural chairman for six years. And after retiring from this post in 2005, he was appointed by the Government to represent Ireland on the World Anti-Doping Association (WADA). Having stepped down recently from that post too, he feels free to express his views on a subject critical to the future of all sport.

"When you consider the idea of a man of 6ft 5ins competing against an opponent possibly a foot smaller, it is fanciful to think of sport as being fair," he said. "But where drugs are concerned, our objective must be to make it safe. Drugs like cocaine, anabolic steroids, growth hormone (hGH) and erythropoietin (EPO) kill people, by damaging the heart, causing tumours and bringing about a whole variety of conditions which shorten people's lives."

Dr O'Brien was not surprised to read last week that Dick Pound, chairman of WADA, shares his view about this year's Olympics. "With current testing procedures so sophisticated, most athletes now realise that if they take drugs they're going to be caught, if not at the Olympics, then afterwards," said the Dubliner. "So you're probably going to see very few Olympic records broken in Beijing. It's a bit like drinking and driving. With so many people being caught, there is now an acceptance that it's something you simply shouldn't do. And if you do, you're unlikely to get away with it."

The ingenuity of the cheats, however, has always seemed to out-manoeuvre the sporting establishment, so why should things be different now? "Because there are no new magic bullets," Dr O'Brien responded. "Drugs which were used over the last 30 years were available in mainstream medicine. Anabolic steroids and growth hormone are used in clinical practice every day of the week. Those drugs were then applied to the needs of the athlete.

"But as far as we're aware, there is nothing new out there, other than stem-cell research and genetic engineering whereby you try and alter your DNA code. This doesn't mean that the situation mightn't be different in six months, but if it's not in mainstream medicine, one of the major drug companies would have to invent it."

What about masking agents? "Masking agents such as phenacitin, which is the one used by Tour de France cyclist Pedro Delgado, is essentially designed to treat gout. What it did for Delgado, however, was to prevent the excretion of anabolic steroids into his urine. But testers are now looking at changes in a person's chemistry. Things like the electron configuration of red blood cells which, if it's abnormal, constitutes a positive test.

"So, not only can testers pick up an illegal substance, they pick up such important changes as the ratio of testosterone to epi-testosterone in an athlete's system. If you suddenly find the ratio is abnormal, then there is either something wrong with your system, or you're getting it from an outside source.

"For the cheat, it's no longer a matter of masking the drug: the effect the drug is having on the system is also being monitored. Changes in a person are observed. If, for instance, a person's blood-count is normally x and it suddenly goes to y, suspicions are raised."

Yet the chances are that some athletes will still try to beat the system, simply because they are risk-takers by nature. We are all familiar with the shocking revelation from the Seoul Olympics in 1988 whereby certain female athletes admitted that, provided they wouldn't be caught, they would be happy to take a performance-enhancing agent if it guaranteed they would win a medal. Even if they were to die within five years of doing so.

There's the rub. According to Dr O'Brien, countries have lost any tolerance they may have had for cheating sportspeople. "The shame which now attaches to being caught taking drugs is immeasurably greater than the simple failure to win a medal," he said. "It is viewed as a far more serious reflection on your country than the most abysmal performance.

"Still, we know that in North America, three per cent of the female athletes in high school and 11 per cent of male high school students have reported experimenting with performance-enhancing drugs before their 15th birthday. So the influence of role models is enormous. Kids copy what they see.

"Elsewhere in the US, attitudes are changing. When it was suggested that baseball was rife with drug-abuse, Americans were horrified, dismissing it as nonsense. Yet the recent report on baseball by George Mitchell was more damning than anyone could have imagined. And we've had the exposure of Marion Jones and the four-year ban imposed on another Olympic sprint champion, Justin Gatlin. But there are rare exceptions. I would view Michael Johnson as a genetic freak, a bit like John Daly and Tiger Woods in golf."

Yet against this background, Tim Finchem, commissioner of the US PGA Tour seemed somewhat reluctant to acknowledge the dangers of drugs in golf, when launching a testing programme last November. "But for the problems in other sports, I doubt we would be at this point," he said. "We are where we are, given the way of the world."

First to institute testing from the start of this season are the LPGA Tour in the US. And it is interesting to note that their commissioner, Carolyn Hivens, has been given no leeway with regard to sanctions. A first violation will bring a one-year suspension and a second, two years. A player found guilty of a third violation would face a lifetime ban.

Meanwhile, as a trained observer of human behaviour, Dr O'Brien has learned that drug-abuse has been part of the human condition for centuries. Indeed going back to Roman times, in the second century AD, it is known that Galen who was team physician to the gladiators -- the first team doctor -- administered berries and stimulants to boost their performance.

And there are actual records of people using drugs in sport in the 19th century. For instance, cocaine and strychnine were found in competitors in a six-mile race in New York in 1872. It was also reported that similar mixtures were used by marathon runners in the 1904 Olympics at St Louis.

Testing was first undertaken at the Winter Olympics in Grenoble in 1968 and at the Summer Olympics at Munich in 1972. At that stage, testers were looking for no more than stimulants, but serious testing began only when anabolic steroids were banned in 1976, 20 years after they had been invented.

"I think we can now say, hand on heart, that it is almost impossible to get round the testing system," said Dr O'Brien. "And the sportsperson must have a very good reason for taking medication, whereas five years ago, a doctor's certificate was accepted. The lines are drawn much tighter.

"Nurture, in the context of drug-taking, has been an attempt to improve on nature. And drugs in sport are no more than a mirror-image of drugs in society. Anabolic steroids, growth hormones and EPO are used not simply by sports people but in the community at large. Research has shown that 20 per cent of people who use cocaine have also used performance-enhancing agents because they give a better cut to your body.

"All the while, there is the impact on youngsters. When I was at school, I wanted to be Willie John McBride, so whatever he did, that's what I aspired to. As it happens, he was a model sportsman. But if we allow our sports stars to be drug abusers, the consequences for society could be devastating."

When the great Italian cyclist, Marco Pantani, the so-called Pirate, died at the age of 34 from a combination of anabolic steroids and cocaine, the Archbishop of Milan reminded the congregation at his funeral that the man was bigger than the bike. That cycling was only a sport, after all. Yet as Dr O'Brien pointed out: "This was poor consolation to his heartbroken mother, who was left with an aching void that would never be filled.

"That's the way it is, when the band stops playing, the champion is put in a coffin and they throw in all his medals. We're all products of the society in which we find ourselves and we owe it to the next generation to show that safe, honest competition is still something to be treasured. That is why the forthcoming Olympics will be so important."

Back in the 1870s, Anthony Trollope complained that "too much is being made of this sport." More than 130 years on, people like Conor O'Brien are trying to convince today's participants that their favourite pursuit is not worth dying for.