Natural History

Pick of the crop

Pick of the crop

Pamela Maher

The book Mendel in the Kitchen: A Scientist’s View of Genetically Modified Foods, reviewed by Laurence A. Marschall [“Bookshelf,” 3/05], suggests that if only people understood the science behind genetically modified (GM) food crops, they would embrace the new technology. As a molecular biologist, I understand the science, and I am very much opposed to GM crops in their present form.

Nina Fedoroff and Nancy Marie Brown are incorrect to imply that GM technology is the same as standard plant breeding. Introducing foreign material into plant DNA is neither “predictable” nor “precise.” The procedures of cell culture and transformation used in producing GM crops cause many random mutations and chromosomal rearrangements. Mutations that cause subtle but significant changes in plant metabolism need not be lethal to the plant; but consuming such a plant could lead to serious health problems.

If GM technology is as safe as Ms. Fedoroff and Ms. Brown claim it is, why are the biotechnology producers so opposed to mandatory safety testing and labeling?

Pamela Maher

La Jolla, California


In our book Nancy Marie Brown and I address all of the issues Pamela Maher raises. Most gene insertions have little or no effect on the plant, but the cell-culture procedures used in transforming some plants are indeed mutagenic. Cell-culture procedures, chemical mutagens, and radiation all have been applied in what people now refer to as traditional, or conventional, plant breeding for the better part of a century. Thousands of new and valuable varieties of food plants, including the familiar Rio Red grapefruit, have been developed through such mutagenic procedures.

Such plants undoubtedly carry genetic changes other than the ones underlying the selected traits. Unexpected health problems due to those genetic changes are rare, though not unheard or. When breeders select for such traits as improved insect resistance, for example, they can inadvertently produce plants with a higher content of toxic compounds than plants naturally produce to defend themselves against pests. Yet traditional plant breeders are not required to do safety testing of new food crops.

For crops derived via molecular techniques, however, the requirements for compositional analysis, as well as for toxicity and allergenicity testing, are rigorous. Hence it is more likely in the case of GM crops that such problems will be caught before foodstuffs come to market. To my knowledge, companies that produce GM foods are not opposed to such testing.

Mandatory labeling is a different issue. It requires that the GM crops be harvested, stored, shipped, and handled separately, all of which translates into higher costs. If the crops look the same as non-GM crops, identifying them requires expensive molecular testing. Mandatory labeling would drive up food costs, but offer no health benefits, and it would disproportionately affect the poorest consumers.

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