What Maria, who asked that her last name not be used, did not know then, but now will never forget, is that the bright orange powder is nearly 90 percent lead.
Fortunately, doctors detected the dangerously high levels of the toxic metal in the little girls' blood during a routine checkup a week later.
But others are not so lucky. Health departments around the country say traditional medicines used by many immigrants from Latin America, India and other parts of Asia are the second most common source of lead poisoning in the U.S. -- surpassed only by lead paint -- and may account for tens of thousands of such cases among children each year.
Dozens of adults and children have become gravely ill or died after taking lead-laden medicine over the past eight years, according to federal and local health officials.
The dangerous medicines are manufactured outside the United States and sold in the U.S. by folk healers known as curanderas and in ethnic grocery stores and neighborhood shops that offer herbs and charms. They are usually brought into the country by travelers in their suitcases, thereby slipping past government regulators.
"No one's testing these medications," said Dr. Stefanos Kales, an assistant professor of environmental health at the Harvard School of Public Health who researched the problem. "There's no guarantee it doesn't have dangerous levels of lead."
Lead is added to many of the concoctions because of its supposed curative properties, even though doctors say it has no proven medical benefits. In other cases, powders and pills become contaminated with lead from soil or through the manufacturing process.
"Instead of doing something good for them, I did them more harm," said Maria, whose children have shown no ill effects. "I was so afraid of all the things that could happen to them. It was a terrible experience."
In Harris County, which includes Houston, traditional medicines are blamed for nearly one-fifth of all cases in which children were found to have high levels of lead. In Arizona, home remedies account for one-fourth of childhood lead poisoning cases.
In Texas, California and Arizona, lead poisoning has been traced to Mexican remedies such as greta, azarcon and rueda -- powders that are given to treat constipation in children and contain as much as 90 percent lead. In New York City and Rhode Island, high lead levels in the blood have been tied to litargirio, a powder containing up to 79 percent lead. It is used by Dominican immigrants for such ills as foot fungus and body odor.
Dangerous amounts of lead have also been found in ayurvedic medicines, which are used in India and commonly found in South Asian immigrant communities in New York, Chicago and Houston. These medicines include ghasard, a brown powder given to relieve constipation in babies, and mahayogaraj gugullu, for high blood pressure.
Traditional medicines may account for up to 30 percent of all childhood lead poisoning cases in the United States, according to the Centers for Disease Control and Prevention. The Environmental Protection Agency estimates 240,000 U.S. children were diagnosed with high blood lead levels in 2004 to 2006.
Many more cases are almost certainly going undetected. Only 14 percent of children are tested for lead nationwide. And the source of lead often cannot be traced in cases where paint is not the culprit.
"I don't think anyone has a good handle on the exact prevalence of use," Kales said. "I'm sure it's underreported because doctors don't generally ask about this and patients don't report it."
The use of folk medicine is rooted in generations-old cultural traditions. Ayurvedic medicine, for example, originated more than 2,000 years ago in India, where 80 percent of the population uses it.
"People think, well, my grandmother did it, so it's not a problem. It's extremely hard to change cultures and beliefs," said Brenda Reyes with the Houston Health Department.
In Houston, where one in four residents is foreign-born, Health Department officials routinely pay undercover visits to herbalist stores and try to buy remedies known to contain lead. Often, however, storekeepers are reluctant to admit they carry the medicine, bringing them out only when they know the customer, Reyes said.
In Houston and other places, health authorities can do little more than ask stores to take such products off their shelves.
In a 2004 study that found high concentrations of lead in ayurvedic medicine, Boston University researcher Robert Saper bought 70 different ayurvedic remedies at 30 stores within a 20-mile radius of Boston City Hall. One in five contained potentially harmful levels of lead, mercury and arsenic.
After Saper's study was released, health inspectors in Houston, Chicago, San Francisco and New York City conducted sweeps, and also discovered dangerous ayurvedic remedies on store shelves.
Lead poisoning can cause lethargy, confusion, learning problems and convulsions, and in severe cases can lead to irreversible brain damage and death. In severe cases, children are often given oral medication to reduce the lead in their bodies, or undergo chelation therapy, which captures lead in the blood and allows it to be removed through urination.
Patients sickened by home remedies often have more serious cases of lead poisoning than those poisoned from other sources because the medicines frequently contain extremely high concentrations of lead and are deliberately swallowed, said Mary Jean Brown, chief of the CDC's lead poisoning prevention branch.
In 2004, the CDC reported 12 cases of lead poisoning associated with ayurvedic remedies in Texas, New Hampshire, Massachusetts, New York and California. In one case, a 37-year-old woman, hospitalized with abdominal pain, nausea and vomiting, reported taking five different traditional medications for rheumatoid arthritis.
Many state and local health departments have issued warnings about lead in folk medicines, and sometimes use questionnaires to screen youngsters in poor neighborhoods and immigrant communities for lead poisoning from folk remedies. The Food and Drug Administration has also issued alerts about certain medicines, including litargirio.
Maria is doing her best to spread the word about the dangers.
"I told everyone in my family, all my friends, not to use this anymore, not to give your children anything if you don't know what's in it," said Maria, who purchased greta during a visit to her hometown in Mexico.
Maria gave each of the girls less than a teaspoon of greta -- enough to send their blood lead levels well over the safe limit. A year later, their levels are still high, but inching closer to the acceptable range. The amount in their systems was not high enough to require any treatment.