Studying Lead in Tijuana Tots.

Researchers at the University of California at Irvine have recently completed a three-year project to assess lead exposure in more than 1,719 children in Tijuana, Mexico, and launch a lead prevention public health program there. Besides already producing positive effects in Tijuana, researchers say, the program could eventually lower the risk of lead poisoning among migrant children in the United States, since many of those children come from Tijuana.

During the project, led by Jon Ericson, a professor and interim chair of the Department of Environmental Analysis, and Dean Baker, director of the College of Medicine's Center for Occupational and Environmental Health, nearly 11% of the children were found to have unhealthily high concentrations of blood lead. Their exposure was traced primarily to lead-glazed pots fired at low temperatures, the cookware of choice throughout much of Mexico. Researchers identified other sources of exposure as well, including dust found inside homes, soil outside homes, and lead-based house paint. The mean blood lead concentration measured was 5.5 micrograms per deciliter. This concentration is not considered life-threatening, but it can affect IQ, attention span, and ability to learn, says Baker. "The children also may have more illnesses and become more belligerent and violent," he says.

The Tijuana children's blood lead concentrations were more than double those found in U.S. children in studies conducted in the past 5-10 years. Researchers found another cause for concern: In U.S. studies, blood lead concentrations decreased with age, while in Tijuana, they stayed the same or increased with the child's age, perhaps because of the continued use of lead-glazed pottery and the fact that Mexico only began phasing out leaded gasoline in 1992. Researchers also found that children whose families had little or no access to health care and whose mothers had less than a sixth-grade education and cooked with ceramic cooking pots were six times more likely to have lead poisoning. After working with parents to identify sources of lead exposure and educate them about how to minimize those risks, however, the researchers saw blood lead concentrations fall in nearly all of the children who were part of the study's case management program.

Even though cooking pots are the primary culprit, Ericson cautions that lead in soil contributes to the problem in Tijuana as it does in the United States, although children in the Tijuana study typically were exposed to lower soil lead concentrations than U.S. children in some urban areas. But even in small amounts, lead from the soil can elevate blood lead concentrations in children.

The research team worked with health care professionals in Tijuana to implement a sustainable system under which the city could continue to monitor lead levels, diagnose and treat lead poisoning, and educate citizens about prevention. "More than 1,000 public health professionals in Tijuana, including 205 physicians, nurses, and epidemiologists, have been trained in lead poisoning prevention," Ericson says. In addition, an analytical laboratory in Tijuana's General Hospital has been certified by the Centers for Disease Control and Prevention to perform blood lead screenings for anyone living in Tijuana.

Martha Vazquez, the binational coordinator with the Irvine team, believes that the percentage of children found to be exposed to lead is cause for real concern. "This means that the health sector in Tijuana needs to start working at the primary [care] level," she says.

She admits that it won't be an easy task. "We don't have a lot of money to promote health education," she explains. "During the study I was perfectly sure that 2,000 families and 500 doctors were educated [about lead]. But the population of Tijuana is over a million."

Vazquez believes that, once all the final data from the study are analyzed, the Mexican government will make the lead program a higher priority. "In Mexico," she says, "there are not enough human or economic resources for preventive medicine and educational programs, but at the primary level they can do a lot."