In the town of Zimatlán, 15 miles south of Oaxaca City, the Zapotec people savor their favorite snack food—a deep fried mixture of pumpkin seeds and rust-colored grasshoppers, called chapulines. Customers at the town market buy the food by the bagful from local vendors, and many ship packages of it north to their family members living in the U.S. to remind them of home.

Teresa Mendez, a cook at the market, frequently sends packages of the food to her grandchildren living in the Bay Area of California. “It’s comfort food,” she told a reporter from the San Francisco Chronicle. “Food keeps us connected.”

However, many of the Zapotec relatives from Zimatlán living in the Monterey Bay community of Seaside, have alarmingly high levels of lead in their blood. Health authorities in Mexico and in California trace the lead poisoning among the Seaside Zapotec people to the foods shipped up by their family members in Zimatlán.

“We are seeing an alarming rate of acute exposure,” a Seaside doctor indicated. He says many of the Seaside Zapotec people have higher blood lead levels than any other community in Monterey County. Some of them have blood levels that reach 20 micrograms per deciliter. Margaret Handley, an epidemiologist at the University of California San Francisco, fears that other Zapotec communities elsewhere in the U.S., who have families in Zimatlán, may also be poisoned with elevated blood lead levels.

Medical tests have also linked dried herbs, hot sauce, and mole—sent north to relatives in Seaside—to the lead poisoning. But the special focus seems to be on the grasshoppers. Handley found that one grasshopper from Zimatlán exceeded by 60 times the FDA recommended permissible lead level in food for children.

Mario Villalobos, a scientist at the National Autonomous University of Mexico, who works with Handley, indicates that the Zapotec season the grasshoppers with garlic, salt, chili power, and lime juice, then fry the food in lead-glazed pots. A chemical reaction during the frying allows the food to absorb lead from the glazing. The scientists have not figured out why similar foods from other Mexican communities, also shared with family members in the U.S., are not causing similar levels of lead in the blood of the consumers. The problem seems unique to Zimatlán.

Warnings in Seaside by the health authorities about the consequences of eating the lead-poisoned foods are not being heeded. The Zapotec love their deep fried chapulines too much to change. In Seaside, notices posted around town and warnings on the Internet have little impact, according to Veronica Aragon, herself a native of Zimatlán. They will not convince people to stop eating things they enjoy. “Food sent from home is so tasty and means so much to people here. People say, ‘How can you come and say lead is dangerous? Prove it,’” she said.

At the market in Zimatlán, Maria Luisa Quevedo is defensive about the glazed pots she sells. “We’ve cooked this way for years, and we’re all fine,” she said. She pointed out her grandmother, a 92-year-old woman stirring beans in a large glazed pot. “Look at her. She’s fine.”