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NEURAL TUBE DEFECT AFFECTED BIRTHS
AND RATES PER 10,000 LIVE BIRTHS(*)
BY COUNTY OF RESIDENCE, 1997
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Source: Texas Department of Health, Texas Birth Defects Registry.
Rates for counties are from 1997; State totals are from 2000.
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Are hazardous and toxic wastes responsible for an unusually high number of birth defects
recorded in the 1980s and 1990s along the southern Texas-Mexico border? While the answers are far from conclusive, many community and environmental groups, as well
as scientists, believe that certain types of birth defects are linked to exposure to pollution from industrial facilities. The controversy along the border dates back to April 1991, when
three women at one hospital in Brownsville, Cameron County, Texas, gave birth to infants with anencephaly, a rare birth defect in which babies are born with either incomplete or
missing brains and skulls. Other similar defects -- such as spina bifida and encephalocele -- are together classified as Neural Tube Defects.
Following this unexpected event and the public outcry it generated, the Texas Department of
Health and the U.S. Centers for Disease Control conducted a joint study to identify cases of both anencephaly and other birth defects known collectively as neural tube
defects and to search for causes. A total of 68 of the defects were discovered among pregnancies conceived in Cameron County from 1986 to 1991, about twice the
rate in the United States during the same time period. Moreover, in 1990 and 1991, the rate was nearly 27 per 10,000 births, about six times the national average.*
The report of the joint study concluded that the causes of these high neural tube defect rates could not be
determined.* Toxics, notably organic solvents, have been suggested as possible candidates that could be investigated
further. Some studies have pointed to a link between the occurrence of the defects and certain occupations, such as painters, in which the parents are exposed to solvents.* Moreover, environmentalists point to the rapid industrialization
in Matamoros, Mexico, as a potential source of high levels of toxics emissions in water and air.*
Unfortunately, relatively little is known about the amounts and types of wastes released by the primarily U.S.-owned
companies operating on the Mexican border. In the United States companies are required to report this information
under the Toxics Release Inventory Program; in Mexico, there is no such requirement. In 1996 a group of Brownsville
families who had suffered through neural tube defect pregnancies settled a lawsuit against several maquiladoras in
Matamoros, including some owned by U.S. companies like General Motors and AT&T.*
In 1992 the Texas Department of Health and the U.S. Centers for Disease Control began the Texas Neural Tube Defect
Project, which serves the fourteen Texas counties along the Texas-Mexico border. The project tracks neural tube
defect births throughout the border by going through hospital and birthing records. In addition, all women with neural
tube defect births are contacted, interviewed, and, if they are willing, enrolled in a folic acid prevention program to
reduce the risk of another such birth. Finally, the project began a case-control study to attempt to find out the factors
which led to neural tube defect cases in 1993. Based upon past studies, the project identified the following chemicals
as being of concern for further study and blood sampling: arsenic, lead, mercury, nitrates, nitrophenols, and polychlorinated biphenyls.* Since the discovery of the neural tube defect problems, TDH estimates it has spent more
than $4 million on NTD surveillance, research and prevention, as well as the creation of the Texas Folic Acid Council
since proper intake of folid acid during pregnancy can lower the risk of NTD births. Nonetheless, lack of funding has prevented some studies from being completed.*
In 1993, the Texas Legislature passed the Texas Birth Defects Act, which among other provisions, gave the Texas
Department of Health the responsibility of creating and maintaining a Birth Defects Registry to track state-wide birth
defects. Unfortunately, a lack of funding has prevented the Texas Birth Defects Registry from covering every area of the state every year, but significant progress has been made.* For example, statewide, based upon reporting from all
areas, 99 cases of anencephaly and 137 cases of spina bifida were reported in the year 2000 (a rate combined of over 6.4 cases per 10,000 live births).*
While rates and cases along the border in general have declined, in late 2000 and early 2001, Texas officials reported
seven cases of anencephaly in Laredo, a rate of 26.7 cases per 10,000 live births, significantly higher than the rest of
the border. As a result, the Texas Department of Health and the City of Laredo initiated a campaign to inform women
about the benefits of taking folic acid and started a local case-control study*.
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