Beware of Lead in Pottery

Researchers have found that infants in the central state of Morelos have been exposed to high levels of lead, raising questions about traditional pottery enameling methods and the validity of outdated official health standards.

The National Institute of Public Health found high levels of lead in blood taken from the umbilical cords of 303 children born between April and September last year. Their mothers were from both rural and urban backgrounds.

Led by medical science researcher Martha María Téllez Rojo, the specialists found that lead levels exceeded 10 micrograms per deciliter, which prompted the team to carry out further investigations.

“We visited their homes, trying to identify the [lead] exposure sources. We discovered that it mainly comes from glazed pottery. The infants were sent to neonatologist and neurology specialists, who gave them neurological and motor stimulation therapies, in an effort to reverse the damage,” said Téllez.

Mexican potters usually use lead-based enamels as a finish for their products, which are traditionally used for cooking. Constant heating causes the lead to separate and become mixed with the food, explained a specialist from the National Council for Science and Technology, Conacyt.

“There’s vast scientific evidence that prolonged exposure to lead reduces intelligence in developing children. It also provokes anaemia and deficiencies in attention, conduct and growth,” said Marcela Ortíz y Tamayo.

In the long term, lead generates reproductive issues such as spontaneous miscarriage and low birth weights, along with hypertension and kidney damage.
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In the case of pregnant women, lead passes into the placenta and reaches the fetus during key developmental stages, mainly affecting the nervous system.

“The children of our study are doing fine because prompt care was provided, but how many more are born in the country, undiagnosed and without access to proper care?” asked Téllez.

Official standards prohibit the production of pottery glazed with lead at low temperatures and establish the maximum allowed levels of lead in the blood, “but what is considered ‘safe’ is well above international standards,” she explained.

Under Mexican standards the maximum permissible level of lead in pregnant women and newborn infants is 10 micrograms per deciliter, while in the general population the level is 25 micrograms. In comparison, the maximum level in the United States is five micrograms, and it has been proposed that that be reduced to two.

“On average, 16% of the children in Morelos are believed to suffer from lead poisoning. In rural, indigenous, and marginal areas, that figure leaps to 27%,” said Téllez.

For the World Health Organization, lead is one of the 10 chemical compounds that represent serious public health concerns, as it can be directly linked to 600,00 new cases every year of intellectual disabilities.

For Téllez, the solution involves a great swath of government agencies: “The secretariats of Health, Social Development, Environment and Labor should all participate, along with the National Fund for Artisan Promotion (Fonart) and the Indigenous Rights Commission.”

“Even the Education Secretariat could participate, raising awareness among the population. There exist cheap alternatives to lead that give the same finish to pottery,” added Téllez.

She explained that alternative, lead-free enamels have been introduced in the Morelos town of Tlayacapan, “but the progress is slow going.”

The results of the studies will be delivered to the Health Secretariat with the hope that they trigger changes in public health policy, such as the introduction of monitoring lead levels throughout the country.

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About G. William Hood

G. William Hood is a writer, fine arts painter, educator and world traveler. He lives in Cuernavaca with his pet cockatiel, Pepe.
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