TCS Daily

Transgenes Invade Mexico -- So What?

By Ronald Bailey - November 16, 2004 12:00 AM

First, a mea culpa -- nearly two years ago I criticized activist scientist Ignacio Chapela for trying to alarm Mexican farmers about transgenic "pollution" of their local varieties of maize. At the time, I asked two questions -- is he right and does it matter?

A new report issued by the North American Commission for Environmental Cooperation (CEC) under North American Free Trade Agreement points out that genes from genetically modified corn (maize) have been found in traditional varieties grown by Mexican farmers. The transgenes evidently came from corn genetically enhanced for insect resistance that has been imported from the United States. Instead of eating the corn, some Mexican farmers planted it and it crossbred with local varieties. So Chapela was right.

Now we turn to the question, does it matter?

Scientifically, the CEC report basically concludes that crossbreeding between transgenic, conventional and traditional varieties does not matter, that it will not harm maize biodiversity:

"There is no reason to expect that a transgene would have any greater or lesser effect on the genetic diversity of landraces or teosinte than other genes from similarly used modern cultivars. The scientific definition of genetic diversity is the sum of all of the variants of each gene in the gene pool of a given population, variety, or species. The maize gene pool represents tens of thousands of genes, many of which vary within and among populations. Transgenes are unlikely to displace more than a tiny fraction of the native gene pool, if any, because maize is an outcrossing plant with very high rates of genetic recombination. Instead, transgenes would be added to the dynamic mix of genes that are already present in landraces, including conventional genes from modern cultivars. Thus, the introgression of a few individual transgenes is unlikely to have any major biological effect on genetic diversity in maize landraces."

Despite this scientific conclusion, the CEC report recommends that corn imported from the United States be labeled as containing genetically modified organisms and/or be milled at the border so that farmers can't plant transgenic seeds. If transgenic corn won't harm maize biodiversity, why should these expensive processes be required? Because the Mexican government wants to mollify local farmers who have been frightened by activists into apparently believing that evil transgenes will somehow consume their crops.

This is very bad trade policy. Any restrictions on trade must be made on the basis of scientific evidence of health or safety concerns or else the door is open to all kinds of arbitrary trade barriers.

The point is not to fan the fears of Mexican farmers (or other people), but to use science to allay them.

Ronald Bailey is reason magazine's science correspondent. His email is


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