July 10, 2000: In a recent letter to Science magazine (Science 288:1748-1749, June 9, 2000), Professor Jose Domingo of the Rovira i Virgili medical school in Spain, questioned claims that genetically modified (GM) foods are safe. He did so on the basis of searches of the U.S. National Library of Medicine's Medline and Toxline databases that revealed a striking lack of published evidence.

Professor Domingo undertook three Medline searches. The first, which was for “toxicity of transgenic foods,” returned 44 citations (currently 45) of which only one “corresponded to an experimental study.” Of the others “seven were letters to the editors of various journals, comments, viewpoints, or mere opinions ...[that did not] provide a single new experimental result,” and 36 were unrelated to the main topic of the search.

The second search, for “adverse effects of transgenic foods,” yielded 67 citations (currently 72) of which only two were directly related to the subject of interest. Of the two that were relevant, one had come up in the first search, the second dealt with the effect of Bt corn on broiler chickens.

The third search, for “genetically modified foods”, gave 101 citations (currently 111) of which only four corresponded to experimental studies.

A search of the Toxline database yielded no new references concerning “direct studies on the potential toxicity or adverse health effects of GM foods [with the exception of] a few articles, mostly reviews, on the risks for allergic patients...”

These results suggest among many possible conclusions either that toxicology research has shown that GM foods to be safe, but that the biotechnology companies that produce these products have not published the results; or that safety studies have not been done. If the first is true, the research should be peer-reviewed, published and made available to the public. If the latter is true, GM foods should not be put into the market until such research has been completed.