Village of the black teeth

EL TEJAR,Ecuador -- About a year ago, a sturdy 1-year old named Miguel was brought to our makeshift clinic to be tested for lead exposure. His mother, like most young women in the village, eked out a meager living by forming and glazing clay roof tiles in her backyard.

My Ecuadoran colleagues took a blood sample from the boy and about two weeks later, after I had returned to Boston, I got the results. In the United States, doctors jump into action if a child's blood level tops 10 micrograms of lead per deciliter; this otherwise healthy-looking boy had blood levels of 107 micrograms per deciliter -- enough to possibly kill him.

Equally frightening was the finding that the breast milk of his mother, 19, contained high levels of lead. I telephoned Dr. Fernando Ortega, a colleague in the capital city of Quito, and asked him to drive to the village, more than 100 miles away. He and a local nurse provided medication for the boy and told the mother that she should stop breast-feeding.

Unfortunately this village, which I nicknamed Village of Black Teeth when I first visited in 1995, was home to many families like Miguel's. The children, who seem like children everywhere, had teeth marked with black stains or lines -- some were entirely coal black -- a sure sign of severe lead poisoning.

For over a decade, I have researched and tried to help these Quichua Indian children, who are being poisoned by the cottage industry that keeps their families alive. Over the years, my colleagues and I have collected medicines and face masks to help protect the villagers from the lead. My basement is filled with donations to bring on my next trip.

But I am baffled by one essential point: Why are these children, who have lead levels that would probably kill an American child, so apparently normal?

Their parents' daily work involves breaking open discarded automobile and utility batteries, and extracting the lead, which they mix with water to form a slurry. This dangerous liquid lead slurry is then taken from large vats by women and children and glazed by hand onto ceramic objects, especially the overlapping Spanish roof tiles that are seen on most homes in Latin America. The tiles are then baked in backyard kilns, with smoke dusting everything from the grass eaten by the village animals to the children playing hopscotch in the yard.

This lead glazing practice, which makes the roof tiles more durable and shinier, attracting a better price in the market, is also common in other Latin America countries such as Mexico and Peru. The infants and toddlers who live in these villages are never far from their mothers' work. Typical children, they drop their food on the lead contaminated ground, pick it up and eat it, or place food on plates covered with lead dust, and as a consequence become poisoned by lead.

The latest national survey in the United States shows that the average blood lead level in American children is around 1.1 to 1.9 micrograms of lead per deciliter of blood. Any child with blood levels greater than 10 micrograms of lead per deciliter of blood is considered poisoned and treated with powerful chelation therapy medicines. A recent study in the New England Journal of Medicine indicated that even children with less that 10 micrograms of lead per deciliter may develop neurological problems and learning disabilities.

These Andean children had some of the highest levels of lead in their bodies ever recorded. Many of the children had blood lead levels greater than 70 micrograms of lead per deciliter of blood. Some -- like the three surviving children of a man whose nine others had died as toddlers -- topped 100 micrograms per deciliter.

According to the local principal and teacher, the school suspects that as many as 70 percent of the children between the ages of 5 and 12 have serious learning disabilities. Our tests of their attention, memory, and visual perceptual intelligence also indicated serious deficits.

Yet I performed brain electrophysiological EEG type tests on a number of children with blood lead levels higher than 100 micrograms per deciliter and found normal brain neuron activity in the brain stem, a surprising contradiction of medical dogma.

Perhaps the difference lies in their chronic exposure. Instead of getting lead poisoning by swallowing a few lead paint chips, as happens with American children, they are exposed with their every breath. These village children are showing us what happens to the human body when it is continuously poisoned.

In general, children's bodies absorb up to 50 percent of ingested lead through the gastrointestinal tract and from airborne lead particles through the alveolar sacs of the lungs. Adults are less vulnerable because their brains are no longer developing, they eat more well-rounded diets, and their gastrointestinal systems absorb less lead.

Lead is absorbed by the bones, where it may be stored for decades. It is mobilized from bone stores during pregnancy and may reach toxic levels in both the mother's blood and breast milk. In lead intoxicated pregnant women it is transferred across the placenta to the fetus, especially during the second trimester.

This spring, during a visit with Harvard students from my class in neurotoxicology, I was delighted to find that Miguel, now almost 2, was walking around the village appearing normal in all respects.

I tossed him a soccer ball that he caught with normal grasp (a good neurological sign) and he walked over and gave it back to me. I picked him up, gave him a big hug, and found that he was happy and cheerful, and showed no signs of disability.

Later testing of his blood lead level at Boston Children's Hospital showed that as a result of our chelation therapy, it had been reduced to 67 micrograms per deciliter, still a highly toxic level by US standards, but much lower.

The ultimate mystery, of course, is why these villages continue such dangerous work. When I recommended that the villagers abandon their lead glazing activities, some parents responded, "But this is our only means of survival. How will we make a living then?" I had no answer for them -- yet.

Dr. S. Allen Counter is a professor of neurology at Harvard Medical School, a neurophysiologist at Massachusetts General Hospital, and director of the Harvard Foundation. He can be reached at allen_counter@harvard.edu.