11% of Tijuana Children Have High Levels of Lead in Blood

TIJUANA, MEXICO — About 11% of Tijuana children show unhealthful amounts of lead in their blood, mostly due to lead-glazed cookware and contaminated soil, but at levels far lower than feared, UC Irvine researchers concluded after a three-year study by the United States and Mexico.

Similar testing in Mexico City previously found about 27% of children there had unhealthful levels of lead in their bloodstreams.

Lead poisoning can affect brain activity and motor skills. In young children, it can cause permanent damage to the central nervous system.

The $600,000 study was funded by the U.S. Environmental Protection Agency and the Centers for Disease Control, with contributions from the city of Tijuana and the state of Baja California. It tested 1,719 children ranging in age from 18 months to 7 years old in and around Tijuana.

As part of their work, researchers started a lead laboratory and clinic at Tijuana General Hospital. They also trained Mexican health workers to do follow-up visits to the homes of children with high lead levels, counseling parents about reducing lead contamination in the household, in many cases replacing faulty pottery cookware that turned out to be a prolific lead source.

That simple step reversed the lead buildup in most of the affected children, according to the study, which included follow-up testing of children. Only a fraction of 1% of the children had so-called stage-three lead amounts, which require medical treatment.

The EPA sponsored the research in Tijuana because many children living there--nearly 30%, according to some estimates--eventually relocate to the United States and one goal was to reduce the number of U.S. immigrants with lead poisoning.

Winona Victery, an EPA official, said the agency rarely funds studies in foreign countries.

“We recognized the importance of the study when it was first conceived,” she said. “What’s interesting is that we relied heavily on the staff of researchers here in Mexico. We helped train them, but they did a lot of the research. We didn’t just come in and do it for them. Their expertise now is just as good as anybody’s.”

Only a Few Need Treatment

The Tijuana children’s lead levels are about twice that of children in the United States but lower than in other parts of Mexico, said Prof. Jonathon Ericson, an environmental scientist at UCI who helped lead the project.

The study concluded that some 37,000 children of the 344,000 living in and around Tjuana are likely to have unhealthful lead blood levels. But only 0.1% reach a higher, critical level requiring medical treatment.

“The good news is that 89% of population [in Tijuana] is below the threshold level for lead poisoning,” Ericson said.

At a press conference at Tijuana City Hall attended by U.S. and Mexican researchers, Ericson said the study found 186 children who tested with unhealthful levels of lead in their bloodstream.

Although researchers found that most cases of lead poisoning originated from faulty cookware, there were examples of children who contracted lead poisoning in bizarre ways.

“We had a case we called the ‘Chiclets boy.’ He would chew his gum and then put it on the wall of his house to chew later,” said Ericson. “Well, the paint on the wall had lead. He was poisoning himself this way.”

In the case of cookware, the study found that lead-based glazes were not sufficiently cured in kilns, allowing the lead to leach into food during cooking.

The study found that poverty is also a factor. Increased risk is also associated with pets going in and out of houses and tracking lead-contaminated soil into living areas.

Researchers and Mexican officials praised the collaborative program, which left in place an ongoing testing, surveillance and outreach program.

Maria Luisa Volker, lab director at Tijuana General Hospital, said the new equipment and expertise of technicians who operate it is already making a difference.

“We’re now making a positive diagnosis of lead poisoning. Before, it wasn’t always easy to tell a parent why their child was sick or lethargic,” Volker said.