Curbing Nature’s Destruction: Man-Made Chemicals Should Be Embraced Rather Than Vilified

From the May 2001 CEI UpDate

Knowing that Nature never did betray the heart that loved her, modern society embraces the idea that all things “not natural” are evil, while the natural world is solely beneficent. For example, opponents of pesticides and biotech foods characterize these technologies as completely unnecessary and inevitably harmful, insisting that these cures are worse than the diseases they combat.  Like many in society, a town in Texas agreed with these characterizations until they discovered Nature’s betrayal.

In roughly a single day of April 1991, doctors at the Valley Regional Medical Center in the south Texas town of Brownsville delivered three babies with anencephaly. A condition where the brain is stunted or missing, anencephaly is rare, striking only three or four births in 10,000. Yet here were three such births in 36 hours.

Health workers were stunned.  Further investigation revealed that in 1990 and 1991 the number of anencephaly cases in the area rose to twice the normal rate.  Something was clearly amiss.

Many blamed man-made chemicals for these tragic births and ensuing deaths.  Indeed, heavily sprayed cotton and sorghum fields surround Brownsville. Maquiladoras (American factories located on the Mexican side of the Rio Grande) emit pollutants into the air and water.  So certain seemed the connection between man-made chemicals and these heart-breaking births that some of the parents received part of a $17 million settlement with the maquiladoras.

But in 1992, this tidy little theory of man-made pestilence received a rude jolt. Even though farmers continued spraying pesticides and the maquiladoras continued spewing emissions, the anencephaly rate dropped back to normal. Something else must have caused the fatal birth defects.

The Texas Department of Health now thinks it knows the culprit.  It was a completely natural chemical called fumonisin.

Fumonisin is a mycotoxin produced by Fusarium, a ubiquitous corn fungus. If you’ve ever shelled corn for chickens or gleaned a cornfield, you’ve seen Fusarium.  It’s a white cobwebby substance usually located around damaged parts of an ear.  And it is dead common.  Literally. Found in almost every cornfield at harvest, Fusarium kills horses and pigs if their feed has a high enough concentration of the mycotoxins it produces.

Despite its known effects on these mammals, researchers have never established a clear link between Fusarium’s toxins and human deaths.  Studies from South Africa and China have indicated a possible link between high levels of fumonisin and esophageal cancer, but researchers have never clearly fingered fumonisin in these cases.  The same is true in the Brownsville case. 

But while researchers have not directly linked fumonisin to the anencephaly cases, the circumstantial evidence is intriguing.

For one thing, scientific research suggests a mechanism by which fumonisin causes birth defects.  Research has convincingly shown that a lack of folic acid, an essential B vitamin, may cause neural tube defects such as anencephaly.  Cell-level studies reveal that fumonisin interferes with the absorption of folic acid by the cells of the body. Thus a mother could consume folic acid but fail to receive its benefits.  The result is a plausible biological link between the incidence of Fusarium and the tragic cases of anencephaly.

What’s more, Fusarium levels rise when conditions such as drought or insect infestation stress the corn.  In 1988, the country experienced a severe drought that greatly affected the corn crop.  In 1989, corn-fed horses and pigs around the country began to die from conditions caused by high fumonisin levels.  At the same time, the fumonisin levels in the corn products in the Brownsville area began to rise along with the anencephaly rate. 

Finally, the population that bore the anencephalitic babies was Mexican-American. On average, a pregnant Mexican-American woman in Brownsville consumes 90 grams of corn a day in tortillas alone.  In contrast, Canadians consume only 17 grams of corn per day.  While the general Anglo-American consumption rate is not known, it’s a good bet that even in Texas the corn consumption rate is lower than 90 grams a day.

Researchers who study fumonisin levels in corn products think the levels in the U.S. are safe but those researchers note that Mexican masa and tortillas have a far higher rate of fumonisin than do American corn tortillas. While there’s no need to skip the tamales when you’re pregnant, consuming 110 tortillas a month might have an effect.

Most news reporters seem astonished by the possibility that food can harm you, but it’s hardly news that the toxins that exist naturally in food can cause health problems. Ergot, another grain fungus, has a long and notorious history in this regard.

The consumption of a more varied diet and knowledge about the ergot life cycle has greatly lessened ergot’s influence on humans. Ergot is also controlled though crop rotation and the application of fungicides.

That’s right, man-made chemicals curb the destruction wrought by natural chemicals.   But man’s efforts don’t stop there. Agronomists are also investigating the use of biotechnology to curb the incidence of ergot.

Similar solutions might well prove the answer to lowering fumonisin levels in corn as well. Fusarium likes to colonize on stressed corn, and corn becomes very stressed when insects chomp upon it.

Insects such as the corn earworm and the European corn borer regularly damage corn crops both through their initial chomping and the ensuing fungal colonization of the damaged areas. Controlling the incidence of these insects should control the incidence of Fusarium. 

In fact, it does. A recent study conducted at Iowa State University demonstrates that corn that is bio-engineered to express the Bacillus thuringiensis (Bt) gene has a far lower incidence of fumonisin than conventional corn.  But those who oppose biotechnology are pushing for a ban on growing Bt corn, claiming that it has no benefit and ignoring the fact that it could save lives.

Screening for Fusarium in the food supply protects the consumer, but technologies such as Bt corn and pesticides protect both the consumer and the producer.  The producer won’t have to throw out contaminated crops, and the consumer will have a plentiful supply of clean corn.  This win-win situation won’t be brought to you by Nature, who, as Wordsworth himself found out, frequently betrays the heart that loves her, but by your fellow man, working in a lab somewhere near you.

Jennifer Zambone ([email protected]) is an environmental policy analyst at CEI.