http://news.bbc.co.uk/1/hi/sci/tech/3846843.stm

 

Aral catastrophe recorded in DNA

By David Shukman

BBC science correspondent in Muynak, Uzbekistan

 

Fresh fears have been raised about the health of populations living near the shrinking Aral Sea in central Asia.

 

A new study has now found high levels of DNA damage that could explain the region's abnormally high cancer rates.

 

This comes as the latest estimates say the Aral Sea is receding so rapidly it could vanish within the next 15 years.

 

Once the world's fourth largest inland body of water, the sea has been drained by a poorly managed irrigation system that supplies water to cotton crops.

 

Toxic mix

 

If ever there was an example of manmade ecological and human catastrophe, the Aral Sea and the dusty, salt-encrusted lands around it must be the most vivid anywhere on the planet.

 

In fact, it is no longer true to talk of the sea as a single entity. In the late 1980s, its level fell so low that the centuries-old body of water divided into two.

 

In the last eight years, the sea has fallen another 5m (16ft) and soon you can expect official confirmation that the larger of its two parts has been divided again.

 

What is left when these seas retreat is a vision of environmental apocalypse: vast stretches of desert, laden with heavy doses of salt and burdened with a toxic mix of chemical residues washed down over the decades from the farms upstream.

 

Gone are the cooling breezes that once made the town of Muynak attractive.

 

This fishing port used to boast busy docks and the largest fish processing

plant in the Soviet Union.

 

Now the sea is only reached after a long day's driving over harsh terrain. The jobs have disappeared and even the cleanest water is dangerously salty.

 

Cancer rates

 

Dust blows everywhere and carries with it toxins that enter the food chain.

 

The impact on public health is devastating. Malnutrition is rife as are conditions including anaemia and TB.

 

Most alarming is a rate of a particular form of cancer - cancer of the oesophagus - that is the highest in the world.

 

CONSEQUENCES OF SHRINKAGE

 

Aral has moved 100-150km away from the original shore Fishery - 44,000 tonnes per year - has totally collapsed 42,000 sq km of new salty desert emerged since 1966 Diseases - cholera, typhus, gastritis, blood cancer Highest child mortality rate in the former USSR

 

Up to 80% of cancer victims in the region suffer this form of cancer.

 

For years the likely cause has been suspected to be the intensive use of pesticides and herbicides on the vast cotton fields to the south of the Aral Sea. Now new research appears to provide support for that.

 

Dr Spencer Wells, of the National Geographic Society and formerly Oxford University's Wellcome Trust Centre for Human Genetics, studied DNA samples taken from the local population and found widespread genetic damage.

 

The study focused on the level of a marker known as 8-OHdG and showed rates of damage 3.5 times higher than seen in samples from the US.

 

In the wind

 

In farm workers, those closest to the agricultural chemicals, the rate increased to 5 times.

 

According to Dr Wells, the implications of this could be long lasting.

 

"This means not only that people are more likely to get cancer but also that their children and grandchildren are too," he told BBC News Online. 

 

The water has been taken to feed the "white gold" - cotton

 

What is not proven is whether the genetic mutations found in the adults are indeed passed on to later generations. That will take further study.

 

In the meantime, the cancer wards in the main hospital in the provincial capital Nukus are overburdened.

 

One patient is 61-year-old Saparbey Kazahbaev, a biologist who has spent the last 30 years living beside the Aral Sea and studying the effects of its decline.

 

He is now recovering from surgery to remove a tumour from his oesophagus.

 

Too weak to raise himself from his bed, he explained in a rasping voice how the poisonous salts in the air have a double effect on humans.

 

First they enter the respiratory system; second they enter the food chain through plants and animals that are eaten.

 

'No alternative'

 

The government of Uzbekistan denies it has a major healthcare problem on its hands.

 

The worst affected region falls in the province of Karakalpakstan and the region's deputy health minister, Atajan Hamraev, admitted there were problems but said they were under control.

 

We asked him whether it was wise to continue growing cotton, given the way it soaks up all the water that used to flow into the Aral Sea and the new evidence of health risks from the chemicals sprayed on the crops.

 

His response was defiant: cotton is Uzbekistan's biggest export earner.

 

Mr Hamraev said that stopping the growing of cotton would make public health worse and leave stomachs empty. "There's no alternative," he said.

 

So the cotton fields are busy, the sea shrinks and the hospitals struggle to cope.