When the Iron Curtain fell 15 years ago, the free world's scientists got their first good look at the environmental consequences of East Europe's communist economy.
Scientists worldwide have since been studying the region's polluted sites and helping post-communist governments launch massive cleanups of old Soviet military bases, Czech uranium mines and Slovakian chemical plants.
Now, the same scientists are turning their attention to a new and apparently larger environmental challenge -- China.
A window to China's problems with land and water contamination is slowly opening to the rest of the world's environmental experts. As a result European scientists, including some from former communist countries, are getting involved.
Czech plant biotechnology specialist Tomas Vanek, who was recently invited by Beijing authorities to work on soil contamination issues, says: "Now China is starting to cooperate."
An international conference in Nanjing last autumn reflected what appears to be China's growing willingness to accept foreign expertise.
British, Dutch and Czech scientists were among those welcomed to the Soil Pollution and Remediation Conference, sponsored by the Chinese Academy of Sciences and other government agencies.
They focused on ways to remedy environmental problems created by China's ongoing rush to industrialize, modernize farms and expand cities.
Vanek presented a paper on the use of flax and hemp crops to remediate land contaminated by low-level radioactivity.
According to his five-year study, flax can be safely grown in radioactive soil and then harvested for industrial purposes, such as fibres and non-edible oils. Both crops also prevent erosion and provide revenue to offset the costs of managing waste sites.
Similar studies on so-called "phytoremediation" techniques are being conducted around the world.
Swedish scientists are now testing Vanek's idea to grow hemp on polluted land and process the harvested crop for auto insulation, rope or as an energy source.
Vanek said Chinese officials "are very interested" in phytoremediation as a low-cost solution to land pollution.
How much land in the world's largest country will require an environmental cleanup?
"No one really knows," Vanek says. "This data is partially confidential."
Papers presented by Chinese scientists at the conference confirmed Vanek's point. One by four experts from the science academy and a Nanjing university said the amount of soil pollution nationwide is "unclear."
The Chinese experts cited a 1999 Beijing government report which said "various contaminants" had polluted 20 percent of the nation's cropland, while "another report indicated that about 20 million hectares of the cropland was contaminated with heavy metals and about 60 million hectares of cropland was polluted with pesticides and other chemicals."
Other Chinese scientists at the gathering emphasized a need for more basic research, environmental standards and government regulations to clean up polluted land as well as prevent contamination.
A key impetus for giving the environment more attention, the scientists said, was foreign investment.
Multinational companies that have expanded, or may expand, into China often carry their own land use standards which, for example, prevent them from building factories on heavily polluted ground.