TINY LACK RAVAGES CHINESE : IODINE DEFICIENCY DAMAGES MILLIONS.

Byline: Patrick E. Tyler The New York Times

Like a thousand other villages in the rural archipelago of China, this collection of black-tiled roofs and dusty courtyards looks from a distance like just another smudge on the sea of wheatfields blanketing the central China plain.

But soon after you walk under the canopy of poplar trees that shades the neat rows of houses, the curious and childlike faces begin to appear.

They are the faces of China's cretins, the most visible evidence of a generation silently ravaged by the absence of iodine in their diet.

They come with halting gaits down dirt paths or they peer out from darkened doorways with searching, innocent eyes and glowing smiles that render an unworldly elegance.

Though childlike, most are not children. Some are mute, others deaf. They have simple names like ``The Third Wang'' and ``The Fourth Little Zhang.'' They are given simple tasks in the extended family of the village, and the tragedy of their lives seems cushioned by a heartening compassion.

China, renowned for its success in fighting disease, is belatedly campaigning against a preventable medical catastrophe that it somehow overlooked.

China's public health ministry estimates there are more than 10 million cases of mental retardation in the country - including hundreds of thousands with the overt handicaps of cretinism - resulting from iodine shortages during brain development. There is recent evidence that much larger numbers of Chinese had their intelligence lowered to some degree, Chinese and Western scientists say, for want of a simple chemical in their diets.

Understanding of the scale of the disaster seems to grow with each passing year as researchers find that iodine deficiency exists in every province of the country, and its effects are broader than anyone imagined. Tens of millions of people have stunted lives and intellect.

``When you realize the burden of this thing, it's incredible,'' said Glen Maberly, chairman of Emory University's department of international health and one of the first Western scientists to call attention to serious iodine deficiency in China.

``The whole intellectual fabric of a large portion of the population is being dulled,'' he said. ``With the lack of iodine, the brain just does not wire correctly in early development.''

For centuries iodine deficiency has been known to cause goiter, a swelling of the thyroid gland, and in extreme cases to cause the deformities and severe retardation of cretinism.

But research over the last two decades has uncovered far wider, less visible damage. Even where goiter and cretinism are not apparent, iodine deficiency can cause chronic mental and physical fatigue and lesser degrees of mental impairment.

Prevention is as simple as adding trace amounts of iodine to table salt, but even this, in the sprawling setting of a huge developing country, requires a surprising degree of sustained political commitment and technological discipline.

The tragedy may finally be coming to an end in China. The Communist Party leadership, finally recognizing the vast scale of iodine deficiency, has mobilized to eradicate the problem by 2000, with significant assistance from the World Bank and the United Nations.

The goal is to restructure the country's salt industry to iodize salt consumed by the 1.2 billion Chinese, while also eliminating a big black market in salt without iodine.

Reaching that target has proved more difficult than leaders expected when they optimistically predicted that the nation's salt supply would be iodized by the end of last year.

There is still a long way to go. A third or more of the salt consumed today is not iodized, and sales of iodized salt from some government distribution centers are dropping instead of climbing as noniodized salt remains the cheaper option in much of China.

A 1995 survey of newborn infants in every provincial capital showed iodine deficiencies in 35 to 65 percent of those tested.

The World Health Organization says that of the estimated 1.6 billion cases worldwide of iodine deficiency, nearly a third, or 500 million, are in China.

China's vice minister of health, Yin Dakui, said last year that based on testing of schoolchildren in 1995, most of China's population was at risk. Field studies during the 1980s found that up to 25 percent of the schoolchildren in areas suffering from severe iodine deficiency were mildly retarded, with IQs of 50 to 69.

Millions of Chinese who live near the sea get sufficient iodine in their diets from seafood. But subsistence farming on the iodine-deficient soils of inland China and western regions is the core of the problem.

Broad distribution of iodized salt in vast rural regions with poor transportation is a daunting task, and whether China can reach its goal of eliminating iodine deficiency by the year 2000 is problematic.

While efforts continue, awareness is growing of the staggering consequences of iodine deficiency in terms of mental and physical disabilities.

``There is a colossal problem in China,'' said Basil Hetzel, an Australian scientist who is a leading researcher on iodine deficiency and who, along with Maberly, began in the 1980s to press the Chinese government and U.N. agencies to step up the attack on the problem.

``This is much bigger than polio and smallpox, but it doesn't ring the bells like the infectious diseases,'' Hetzel said. ``It is a silent scourge.''

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Photo

Photo: Zhang Ying, 13, who lives in the village of Daxin, i s among millions in China retarded by iodine deficiency.

New York Times