The skin properties of a man discovered in an Alpine glacier in 1991 have remained virtually intact for five millennia, Bradford University pharmacists have discovered.

The scientists have examined the molecular state of 16 milligrams of skin from the body of the late Neolithic man and contrasted it with that of contemporary man using electron microscopy and techniques they have pioneered.

Brian Barry, head of the transdermal drug delivery group, says that the man, referred to as the Iceman, is one of the oldest and best-preserved mummified hu-mans ever found and predates Tutankhamun by 2,000 years.

Professor Barry says that the reason for the 5,200 year-old body's remarkable state of preservation was that the Iceman, who had died in an accident, was buried under ice in a hollow 3,200 metres above sea level.

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"It is likely that the wanderer froze to death before being dehydrated via a process akin to freeze-drying," he says. This meant biological degradation was minimal. To mimic the conditions under which the Iceman's skin was preserved, the researchers freeze-dried modern skin.

A comparison of the molecular structure of the two showed that while the protein content of Iceman's skin had changed considerably, the lipid material remained largely unaltered: the gross structure of his skin had survived virtually unchanged.

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For Professor Barry the findings are further proof of the awesome properties of human skin.

"It is very thin, very elegantly constructed and a remarkable feat of evolution. It is the body's first and foremost means of preventing attack from toxic substances in the environment. Without it you would die very quickly. It is replenished once every two to four weeks and yet here in the Iceman we have the barrier being preserved for 5,000 years," he says.

The work by the transdermal drug delivery group focuses on developing ways of introducing drugs through the skin in such a way that it does not cause major disruption to its integrity so allowing penetration of ambient toxics.

Introduction of drugs through the skin would be much more efficient than the conventional oral method and less painful than injections.

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Despite decades of research into the transdermal delivery of drugs, only a handful have been developed, an indication of what a tough barrier skin presents to the environment.