Note: This article is a sidebar to this issue’s feature story.
BROWNSVILLE, Texas – In April 1991, health care workers in this border town were brought up short. In a matter of hours, three babies were born at the Community Health Clinic with anencephaly, a rare birth defect marked by the failure of the fetus to develop a skull or brain.
It was just the beginning. By the end of 1992, workers had reported 30 cases of the disease, bringing Cameron County to more than triple the national average. Worse, no one could figure out what was causing the disturbing trend. The mothers were mostly poor recent immigrants. In this region, among the poorest in the United States, local health care agencies could do little to help, and the state had no system for monitoring birth defects, much less responding to such an outbreak.
Over the following decade, the state set up the Texas Birth Defect Monitoring Division to track birth defects and search for their roots. But the problem persists. In late 2000 and 2001, another seven newborns in the city of Laredo were born with anencephaly. The Lower Rio Grande Valley has also seen clusters of other neural tube defects, including spina bifida, a malformation of the spinal cord, and encephalocele, an often-fatal disorder that leaves portions of the brain exposed through a hole in the skull.
Texas Public Health spokeswoman Amy Case says state officials have been studying health problems such as obesity, dietary deficiencies and diabetes, which may contribute to birth defects. They are also looking at possible links with agricultural and industrial pollution. “Factors in the environment are always something you have to consider,” says Case. But for the time being, there are no easy answers.
Frogs offer a clue
A recent study from an unlikely source may provide a breakthrough. For 17 years, Oklahoma State University zoological toxicologist Douglas Fort has studied the impact of contaminants and toxins on frogs. Specifically, he looks at how pollution affects frogs’ ability to metamorphose from tadpoles into adults. While he is careful to point out that human embryo development is substantially different from that of amphibians, Fort believes that his work may hold clues as to why so many damaged children are being born in the Lower Rio Grande Valley.
“We’ve found that frogs make a pretty good model from a developmental standpoint,” he says.
Already, Fort has been able to create syndromes in frogs that mimic dietary deficiencies that have been blamed for human birth defects. Now, to study possible connections between birth defects and pollution, he has been exposing frogs and tadpoles to water and sediment from the Lower Rio Grande.
“We’ve been taking samples all the way from the Santa Ana National Wildlife Refuge to Boca Chica (where the Rio Grande meets the Gulf of Mexico, a distance of nearly 200 river miles),” he says.
Lo and behold, many of Fort’s frogs have suffered from developmental deficiencies similar to the neural tube defects found in human newborns. Using water collected from the Brownsville area, Fort has replicated anencephalitic brain deformities ranging from reduced brain size to no brain at all.
The studies provide a strong link between water pollution and birth defects, says Fort, but they offer no smoking guns. “Where (the pollution) comes from, we don’t know,” he says. “There’s a host of possibilities.”
Fingering the factories
Pediatrician Carmen Rocco is less hesitant to assign blame. Rocco, who was the medical director of the Brownsville Clinic during the first outbreak of anencephaly in 1991, has since left the clinic, claiming that the state is turning a blind eye to some of the most obvious polluters in the Lower Rio Grande Valley: agriculture and industry. She is particularly suspicious of the corporations that have set up maquiladoras, or maquilas, along the border, taking advantage of cheap Mexican labor to manufacture items as diverse as computer modems, color TVs and cars.
“Most of the studies so far have been inconclusive,” says Rocco, “but we still think it’s very important to look at how the maquilas and pesticides are impacting our air and water quality.”
Not everyone agrees. “There’s very little credible evidence that the maquilas are doing anything to harm the environment,” says Mike Allen, the president of the McAllen Economic Development Corporation, a nonprofit organization that works to attract new business to the region.
“We all have to live here, and there’s a need to be vigilant,” says Allen, who in a common confusion refers to anencephaly as “encephalitis,” an unrelated mosquito-borne illness. “But (industry critics) never provide specific information about problems with a specific plant. All we’re saying is, ‘Where’s the proof?’ “
Proof is hard to establish, says Miguel Mora, a biologist with the U.S. Geological Survey, who has compiled a database of pollution on the Lower Rio Grande spanning 35 years. The maquilas use a suite of solvents, acids and paints laced with heavy metals, he says. It’s difficult, however, to track where those chemicals end up, and runoff from agriculture and urban areas only complicates matters.
The recent discovery of trihalomethanes in the drinking water of a dozen communities along the Lower Rio Grande has the attention of scientists here. These chemicals – which have been linked to neural tube defects – are created when chlorine, commonly used to disinfect drinking water, combines with organic material and fertilizers. But on a river that has been transformed into a drainage ditch and a dumping ground for a growing border population, tracing human illness to specific sources is sure to be a monumental task.
Dan Oko writes from Austin, Texas.
Copyright © 2002 HCN and Dan Oko
This article appeared in the print edition of the magazine with the headline What is poisoning border babies?.
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