Crop conundrum.

The lead review “Risk assessment of genetically modified crops for nutrition and health” by Magaña-Gómez and Calderon de la Barca,1 ends with a common plea: “more research is needed”. It is valid to put both this plea and the justification for other similar research into perspective. How selective are the reviews that lead to the conclusion that more of such research is needed?What comparators are available? Why genetically modified (GM) crops particularly? And what political effect does the science promulgate; to what advantage and to what disadvantage is global society affected? Magaña-Gómez and Calderon de la Barca1 conclude that at a macroscopic, whole animal level, there is no provable adverse health effect of GM crops, but there is evidence that microscopic and molecular changes may have been induced in animal studies. It is implied that these may be important for safety. But what is the comparator basis for these studies? Crops and plants, in general, are dynamic and complex. At different growth stages, in different environments, as well as in different varieties (e.g., there are more than 20,000 varieties of rice), there will be variations at the molecular and microscopic levels. Research into normal biological variation for any relevant crop species of the growth stages, environmental effects, and variety differences would be useful so that comparisons of the same data, which need statistical analysis anyway, from any GM crop plant could be made based on properly established, statistically valid, baseline data for that species.Yet such research would be very time-consuming, expensive, and unlikely to receive grant funding, so it will probably not be done. Yet, without having a very firm understanding of the breadth of this variation, a comparison of analytical data (chemical or histological) from any sample of a GM crop may only be a comparison with one part of the spectrum of normal variation in that species. Such a comparison is like comparing apples and pears: they are essentially different, which explains any differences. A similar point can be made regarding the utility of animal studies for determining subtle changes that may be due to dietary components, i.e., they may not be very useful. “Normal” individuals of a species exist in many varieties, with many variations including in behavior, metabolism, disease susceptibility, and disease state. Think of humans. If we are really interested in evaluating microscopic, subtle changes to inform us of a potential for hazard in humans, will a 90-day rodent study, using standardized rodents, really inform us, however thoroughly it is executed? To do more is costly in terms of both time andmoney. To sacrifice animals for no purpose is ethically questionable as well as wasteful. Conventional breeding has created plants that are potentially hazardous to humans: certain varieties of celery and potatoes are normally quoted as examples. Of course, these plants have not been developed further. The major concern for human hazard from genetically modified crops is the possibility that novel proteins may be introduced and ingested, and these may prompt potentially dangerous allergic reactions in man. However, sophisticated computer databases have been created that allow for searches of new protein structures to be made and compared against extensive databases of the structures of known human allergens, and these are used routinely as a proxy. The development of some potential GM products has been halted as a result, just as the development of some conventionally bred crop varieties has been halted. Crop plants have been introduced as novel food to previously unexposed populations for thousands of years.2 None of them has been tested for safety before being introduced to the new population. One example is the kiwifruit from New Zealand; originally from China, kiwifruit was introduced to Europe only in 1955. Potato, maize, and tomato are all examples of plants containing known allergens that have been introduced to other populations from their regions of origin, and all are nowadays commonly consumed as food