Thousands of Mexican potters have been unwittingly poisoning their families and customers with toxic lead for 400 years by using lead-based ceramic glazes which lend a lustrous glow to pots, cups and plates.
A team of U.S. and Mexican health and other experts has now launched the first skirmish in a war on lead: 100 pottery-making families have replaced the lead glaze with lead-free glazes newly created by Mexican researchers.
But tens of thousands of potters are still reluctant to change their old ways and many continue to use lead, saying: "It was good enough for our ancestors so it should be good enough for us."
The effects of lead are subtle -- mainly felt on people who suffer a loss of 10 to 20 points on their IQ when their blood lead levels reach around 35 micrograms per deciliter.
The United States on May 16 cut the acceptable limits for lead in children from 10 micrograms to five per deciliter of blood -- the first change in 20 years. But children in pottery-making families have blood lead up to 10 times higher than the new U.S. limits.
"It's hard to explain to them," said Bret Ericson with the Blacksmith Institute, which is carrying out the $120,000 program to end the use of lead glaze in Mexico. "The challenge is people have a cultural attachment to lead glaze. We need to educate people on the dangers."
He noted that after the United States removed lead from gasoline in the 1970s and 1980s, the average IQ score rose around 10 points.
Some 50,000 potters in Puebla, Michoacan, Oaxaca and other states were using lead glazes when the Mexican government asked Blacksmith to tackle the issue about four years ago. Their combined households total 250,000 people -- all at risk from acute exposure to lead.
Children and adults get lead through dust at the kilns and home workshops. They also ingest lead from food stored in lead-glazed pots, especially acidic foods such as salsas which release lead from ceramics.
The effort to get lead out of pottery, funded by the Annenberg and Vista Hermosa Foundations, is just the start of a long war to help millions of people at risk from lead pottery in Latin America and the Middle East. Once a successful model is created in Mexico, it will be applied in other countries.
Four years ago, lead-free glaze cost more than the leaded glaze. Then researchers cut the cost of lead-free glazes below leaded ones. But the new glaze needed higher temperature than the traditional kilns produce -- meaning it would require $10,000 to rebuild each kiln. Last year, researchers produced a lead-free glaze that works at the same low temperature as lead glazes, eliminating the need to rebuild kilns.
The goal is to convert potters to lead free boron-based glazes developed by Mexican universities and industries. The Mexican government asked Blacksmith to get lead out of pottery after the NGO came down to work on the problem of lead pollution in car battery recycling operations.
At one news conference, blood was taken from a potter and from a journalist: the potter had nearly 35 micrograms of lead per deciliter of blood -- seven times as much as the journalist.
If a ceramics maker switches to non-lead glazes, the project cleans up the home and the kiln, removes contaminated soil, and may apply concrete or paint over contaminated surfaces. It is also good business to get rid of lead - the non-lead glaze was more appealing in color and appearance than lead glazes when shown to shoppers.
The project helps potters market lead-free ceramics in the United States by listing them on a website -- alfareria.org -- set up by Blacksmith and its Mexican government partner, Fondo Nacional para el Fomento de las Artesanias (FONART).
About 30 percent of Mexico's urban population use glazed ceramics for cooking and food storage, meaning the risk of lead poisoning goes far beyond the 250,000 families engaged in pottery production. Blood-lead concentrations are 30 to 40 percent higher in families using glazed ceramics.
But where the project has begun its work of community education, blood monitoring, kiln replacement, and removal of lead, blood-lead levels have dropped by half in three months.
Ben Barber is a freelance journalist and communications consultant for Blacksmith Institute.