By Emma Graham-Harrison
BEIJING (Reuters) - China's environmental woes spilled visibly over its borders as a toxic slick flowed into Russia in December, but exports of pollution are becoming as common as sales of cheap T-shirts for the economic powerhouse.
The country's leaders are only starting to grapple with the political fall-out at home after years of pursuing economic expansion at almost any price.
Dirty or scarce water, choking air and toxic factory effluent are some of the common problems fouling China's environment and its neighbours'.
Yet the international impact of China's problems have barely registered as cause for concern for Beijing's leadership. It took days for China to notify Russia that an explosion at a petrochemical plant sent 100 tons of benzene compounds pouring down a tributary to the Amur.
Smog carried over the Pacific to the west coast of the United States, acid rain in South Korea and Japan, and destruction of forests as far away as Africa. These are among other unwelcome exports that experts say might cloud China's hopes of being seen as a responsible global power.
"At the moment, China's top leaders have not realized how important, in terms of international relations, environmental conflicts can be," said Ma Zhong, vice-dean of the School of Environment and Natural Resources, at Renmin University.
"They are more concerned about economic and social relationships."
For China's neighbours, the three are inextricably linked.
Nearly half the world's population lives in river basins which have their source in China, according to Leo Horn, an adviser to Britain's Department for International Development.
Among them are some of Asia's great rivers, such as the Mekong and the Indus. Although these have so far escaped the worst of the pollution plaguing domestic waterways like the Yangtze, Beijing has already been feuding with its neighbours for years over plans for dams. Worse might follow.
"These are not the most polluted in the country ... but the sheer scale of our economic expansion means that in remote areas, activities will increase and problems will get worse," said Ma Jun, author of the book "China's Water Crisis."
China's reluctance to sacrifice growth for a cleaner environment causes problems even further away -- some of the industrial smog that shrouds its cities drifts over to dirty air along the west coasts of the Americas, scientists say.
But old attitudes that resources are for fuelling growth, and environmentalism is a bourgeoisie indulgence, are changing.
Top leaders recently pledged to tackle the country's "grim" environmental situation, put energy efficiency in their economic blueprint for the next five years and weigh the financial cost of pollution.
But for some countries, their problems began when China moved to address devastation at home.
Beijing brought in a ban on most logging in the late 1990s, after deforestation was identified as a key factor behind large-scale floods that affected around one-fifth of the population and cost billions of dollars.
It closed off its own forests at a time of growing appetites for wooden products among the newly affluent and an expansion of furniture exports.
The combination sent Chinese firms over the border into Myanmar (formerly known as Burma) while buyers headed as far afield as Liberia and Indonesia.
"China has increased domestic use, increased exports and has few trees it can legally cut -- you can do the maths yourself," said Susanne Kempel, campaigner with British NGO Global Witness.
"It is essentially exporting its problems of deforestation to countries that often have less control or are politically unstable."
Around a million cubic meters of wood crossed the border illegally last year from areas of northern Myanmar identified as one of the most diverse ecosystems in the world, she says.
Even when China is not directly harvesting other nations' resources, its companies, scouring the globe for energy and minerals, can wreak havoc with badly managed mines or drilling.
"There is a lack of systematic consideration of environmental issues in China's trade and investment decisions," said Beijing-based Horn.
But China should not take all the blame for pollution caused by a high level of manufacturing within its borders since many products are destined for Western markets, say environmentalists who hope consumer pressure could force firms to clean up.
"China is now the workshop of the world, and while Westerners enjoy cheap commodities ... we are dumping all the waste in our own backyard, our own rivers," said Ma.
"Consumers have a responsibility in this," he adds.