The Aral Sea, which straddles Kazakhstan and Uzbekistan, was once the world's fourth-largest inland body of water. Today, however, it has shrunk to half its original size, due in large measure to the diversion of its feeder rivers for irrigation. This environmental catastrophe is being compounded by a related health crisis among the local population. Local populations are battling anemia, tuberculosis, and cancer believed to be linked to toxic residue left behind by evaporated Aral water. A new study finds that the Aral catastrophe is being imprinted on the DNA of local residents, raising fresh fears over the long term.
Prague, 9 July 2004 (RFE/RL) -- The gradual shrinkage of the Aral Sea over the past decades has laid bare about 50,000 square kilometers of seabed -- an area larger than Estonia. This new desert is contaminated by a toxic mix of chemical residue washed down the Syr Darya and Amu Darya rivers from farms upstream.
Shirmuhammad Yusupov of Uzbekistan's Agriculture Ministry says these poisons are spread by the wind and are causing widespread health problems in the local population.
"Several kinds of toxic salts are spreading from the Aral Sea across the Central Asian region and outside it, and is harming people," he says.
A new study, funded by the NATO Science Program, provides support for the belief that chemicals used on the region's vast cotton fields are linked to alarming rates of cancer in the region.
The study was conducted in collaboration with the Institute of Immunology in Tashkent and Texas Tech University in the United States.
Doctor Spencer Wells of the National Geographic Society in Washington has studied DNA samples taken from residents of Uzbekistan's Karakalpak Autonomous Republic.
"[The study] shows that there is a very high level of what we call 'oxidative stress' in these people. They're being exposed to something which is causing problems in their DNA and their actual genetic code," Wells says.
DNA is the acronym for deoxyribonucleic acid, which encodes genetic information in cells and determines their structure, function and behavior.
The study in Karakalpak shows rates of damage 3.5 times higher than those seen in samples from the United States. The rate increases to five times higher in those farm workers living the closest to the agricultural chemicals.
Wells says high levels of DNA damage could explain the region's abnormally high cancer rates. In particular, residents of Karakalpak suffer from the world's highest rate of cancer of the esophagus.
"This potentially could help to explain some of the health problems that they have, particularly the cancers. We believe it's through exposure to toxic substances in the environment -- pesticides [and] herbicides -- that are being applied to the cotton fields upstream," Wells says.
The poisonous residue in the air affects humans in two ways. It enters both the respiratory system through breathing and the food chain through plants and animals, which are then eaten.
Even more worrying is the possibility that these genetic changes are being passed down to later generations.
"There is a generalized level of genetic damage,” Wells says. “Presumably that is also going to be seen in the sperm and the eggs. So, in theory, these changes could be, in part, transmissible to the next generation."
Wells says he had made a plea for the Uzbek government to re-evaluate the way it cultivates its cotton crop, the country's biggest export earner.
Uzbek officials admit the problem, but say there are no ready alternatives to current agricultural methods.
(Khurmat Babadjanov of RFE/RL's Uzbek Service contributed to this report.)