To the editor:

As a representative of a recently formed biosafety discussion group in Mexico with an interest in plant-manufactured products, I and the group applaud your editorial in the February issue (Nat. Biotechnol. 22, 133, 2004) highlighting the controversy over the use of food crops, such as maize, in the production of pharmaceuticals.

The article suggests two nontechnical levels of segregation to prevent drugs or drug intermediates in food or feed crop species finding their way into the food chain: geographical and cultural. From our perspective in Mexico, the second choice (that is, not using food plants for producing drugs or other industrial compounds) is the best. Although geographical segregation might work in some regions and countries, this is not the case in Mexico, even if we were to decide to consider its territory a 'drug-producing plant'–free area.

Mexico's domestic maize supply, including imports (6 million tons during 2001; ref. 1), runs on the order of 24 million tons. Fifty-three percent of this is used as food1. We import maize grain from the United States every year, we have migrants moving between the United States and Mexico constantly and we share borders where pollen does not need a passport for free movement. The average maize consumption in Mexico runs in the order of 350 grams daily1, which translates into around 600 (ref. 2) culinary dishes. This means that maize intake is probably one order of magnitude higher in Mexico than it is in the United States. This maize is consumed in the form of products much less-processed than those in the United States.

At the First Meeting of the Parties of the Cartagena Protocol on Biosafety held in Malaysia last February, Mexico officially stated that it will prohibit the release into the environment of genetically modified (GM) maize that could be regarded unsuitable as food3. Even though this is an important and relevant move, it will not be effective unless the three National American Free Trade Agreement countries agree to similar policies.