MEXICAN POTTERS CAUGHT BY FEARS ABOUT LEAD GLAZE : OFFICIALS SLOW TO FIND ALTERNATIVES.

Byline: Julia Preston The New York Times

Juan Juarez has been shaping clay pots and stoking kilns all his life, just like his wife, his brothers, his father and his father's father. He bristles at the suggestion that the family art may have damaged the family health.

``When I was a baby, my mother gave me chamomile tea from cups like the ones we make,'' Juarez said, a touch defensively. ``My wife gave our babies tea from those cups. My son does well in primary school. My daughter is a whiz - she plays the piano!''

Juarez, and virtually everyone else in this village in the western state of Oaxaca, uses lead monoxide to prepare the glazes that give a warm green shade and high shine to its distinctive plates and bowls.

But lead is a poison. It can slow the growth and erode the intelligence of newborns. In adults, chronic lead exposure can cause headaches, digestive distress and depression. In very high doses, it can kill.

Studies over decades have shown that people in Mexican potter communities where lead glaze is used suffer from abnormally high levels of lead in their blood. In one recent case, the 3-year-old daughter of a potter family in another state died in convulsions after swallowing lead.

But Mexican potters and their clans, who number some half a million people, still scoff at the idea that they are vulnerable to lead poisoning.

``How could we make such beautiful pottery if we were dull and sick?'' asked Adelina Vazquez, a craftswoman here.

In April, after years of research and browbeating by alarmed public health specialists, the Mexican government devised the first glaze for artisan pottery that contains no lead. It is in the final stages of testing and will be ready for mass production in 1997.

The government acted because lead poisoning has become ``a leading public health problem in Mexico,'' said Dr. Mauricio Hernandez Avila, head of research at the National Institute for Public Health. Folk-craft plates are used all across the country. Mexican cooks set big clay bowls directly onto their stoves to simmer thick sauces and succulent stews.

With time and use, the lead leaches out of the glaze into the food. In a 1995 study in Mexico City by Hernandez and other scientists, 44 percent of a random sample of children under 5 from working-class neighborhoods had higher levels of lead in their blood than are healthy, based on U.S. standards.

In a study by the team of Dr. Lourdes Schnaas, also in Mexico City, one-third of a sample of otherwise normal children under 2 had lead in their blood ``high enough to require treatment.'' Both studies pointed to lead-glazed ceramic pottery used at home as the principal source.

Babies born to mothers who routinely used this type of pottery had lead levels 65 percent higher than babies born to mothers who did not.

The Mexico City studies showed that lead released from gasoline into the air is a diminishing source of contamination since the government introduced unleaded gas a decade ago.

A former U.S. ambassador, John Negroponte, provided a demonstration case during his tour here. In 1991, a routine blood test on his 7-year-old daughter came back with disturbing results: her lead concentration was four times the safe limit.

A State Department health team undertook a ``Sherlock Holmes-type of operation,'' Negroponte said by telephone from the Philippines, where he is now the U.S. envoy. They seized the culprit in an embassy pantry: a deep clay bowl that had been used to serve the lemonade at a recent picnic for embassy children. The ambassador's daughter drank from the bowl at the party and again repeatedly over the next few days.

``She got a terrific dose of lead,'' Negroponte said. Because he took his daughter immediately for treatment, to Children's Hospital in Boston, she did not become seriously ill or suffer any apparent long-term effects.

As long ago as 1878, a Mexican doctor named Gustavo Ruiz Sandoval wrote a broadside against ``this terrible evil'' after observing victims of pottery lead in Oaxaca. But the current campaign was driven by economics, not health.

A ban in the United States on crockery plates from Mexico coupled with new, tougher lead standards in this country battered the market for handicraft pottery. Sales plunged even for the many styles of Mexican pottery that use no lead or are fired at high temperatures, removing the risk of toxic seepage.

Government officials who worked closely with the potters shared their ambivalence and sought to hold off enforcement of the new lead standards while they searched for a safe glaze.

``We were going to have the second Mexican revolution on our hands,'' said Esperanza Salinas Amezcua, who is in charge of the official pottery lead program. ``It wouldn't be just a health problem. Making pottery is a matter of survival for these communities.''

The government spent $1.5 million on researchers who mixed and tested until they found an unleaded glaze that works with the low and uneven heat of Mexican potters' wood-fueled kilns.

The potters remain convinced that the lead scare is simply a foreign conspiracy. In the bare dirt courtyard of Hermila Martina Lavida, a 64-year-old potter, lead oozes out of an overturned bucket of unused glaze and spills from a torn bag of lead powder ready for grinding in a crude stone mill.

``We eat lunch with glaze on our hands!'' Lavida said defiantly as her young granddaughter kneeled in a corner molding the clay on a twirling wheel. ``And there aren't any deformed children here.''

But the town physician, Dr. Nahum Perez Garcia, said he sees plenty of chronic lead poisoning in children and adults in his clinic. The laboratory tests needed to confirm his diagnosis, however, are expensive and hard to get. His patients ignore him when he orders the lead blood test.

``They refuse to be treated,'' Perez said. ``Making pottery is their heritage. They're afraid someone will take it away from them.''