Julian Savulescu told The Sunday Age it was absurd to crack down on players for allegedly taking banned ‘‘natural’’ substances, while allowing clubs to inject players with highly addictive painkillers and other potentially harmful drugs.

The Australian-born professor of practical ethics at the University of Oxford, called on the AFL to pull out of the ‘‘outdated and unethical’’ World Anti-Doping Agency (WADA) code and allow players to take performance-enhancing substances, under medical supervision.

‘‘Why are we wasting millions of dollars of taxpayers’ money vilifying people for taking safe, natural substances to help them recover from injury?’’ he said. ‘‘You would have thought they were an international ring of paedophiles given the amount of money, legal expertise and attention this issue has received. It is a national embarrassment.’’

On Thursday, 34 Essendon players were issued with show-cause notices by the Australian Sports Anti-Doping Authority (ASADA), relating to use of the substance Thymosin Beta 4, which has been banned since 2011.

Professor Savulescu, a medical doctor and strident critic of the war on doping, said the AFL, WADA and ASADA did not care about player welfare as there was no evidence anyone had been harmed by the peptides regime.

‘‘The alleged substance, Thymosin Beta 4 has only ever been used in clinical trials to assist regeneration and repair after damage. It would promote player health. Yet analgesics and local anaesthetics are allowed by WADA and ASADA which increase damage...the rules are either unclear or poorly based on any coherent ethic. Caffeine is performance enhancing  - it is not natural to the body and it is dangerous if taken in large amounts. On the evidence available, Thymosin Beta 4 seems safer than caffeine.’’

He added that allowing the use of substances which leave normal physiology intact would be a more safe and enforceable system, while allowing sports regulators to focus on dangerous drug-taking that corrupts the spirit of the sport. ‘‘Assisting recovery is not against the spirit of sport - it is the point of medicine,’’ he said.

However, Leslie Cannold, a medical ethicist from Monash University said the position was flawed and irresponsible, as the long-term effects of banned substances had not been adequately tested. She argued that player welfare would be best served by the AFL remaining a signatory to the WADA code.

‘‘The only way to manage the drugs in sport issue is to regulate. It’s the only way to protect the capacity of athletes to compete fairly just on what they were born with, combined with the hard work they put in. Athletes who want to play sport should be allowed to without having to agree to put untested, unproven and potentially unsafe substances in their bodies in order to be on a level playing field with their peers,’’ Dr Cannold said.

John Rogerson, chief executive of the Australian Drug Foundation - a key adviser to the AFL on drugs issues - said sports fans needed to be confident athletes were playing the game naturally and without enhancement.

‘‘We also can’t forget the impact the Essendon situation has had on the players and their parents. If we want our kids to play sport then their families need to know they’re not going to be treated as guinea pigs. If we’re going to turn it into an exercise where it’s all about drug-taking then we can forget about the integrity of sport, and that will have a huge impact on the health and welfare of our community.’’

jstark@fairfaxmedia.com.au