DESIGNER food may drive people crazy, but not quite in the way biotechnology firms would want. A few weeks ago, an unidentified group destroyed a test field of genetically engineered maize in Holland. And, there is growing concern in the USA about the effects of genetically modified food on human health.

Dutch protesters cut the stems of transgenic maize plants carrying an extra gene to make them resistant to a herbicide. A plant breeding company, VanDerHave said the vandalism set back their research by a year. The protesters identified in New Scientist (Vol 135, No 1835) as members of Vurige Virus (the ardent virus) later delivered a statement to the local radio station claiming responsibility for the damage.

An announcement by the US Food and Drug Administration that genetically engineered fruits and vegetables will not be tested or labelled before they are put on sale, has aroused public fears. Many non-governmental groups contend this will greatly endanger health because consumers would be eating food without knowing the type of gene that has been introduced into it and what harm it this could do. For instance, plants naturally produce a variety of compounds that are toxic or antinutritional, but their concentration in most species is too low to cause health problems. But genetic engineering could activate toxicants to unacceptable levels. Another fear is that new proteins that could cause allergic reactions may be introduced into a food plant, and consumed unknowingly.

Traditional techniques for breeding allows for hybridisation between two plant varities but not for breeders to modify its genetic structure. But, recombinant DNA techniques such as genetic engineering allow plant breeders to transfer any single gene trait to another organism, irrespective of mating barriers. This technique has considerable precision and breeders are now working on food crops that can resist adverse weather conditions, that can tolerate chemical herbicides and that have improved characteristics for food processing and nutritional content.

One of the first such foods to hit the US market will be the "Flavr-Savr" tomato, developed by the Galgene Co. The tomato has been genetically altered so it no longer produces the rotting enzyme. Its breeders contend the risks were well-considered and, in any case, bioengineering is just an extension of traditional breeding technologies.

Public perceptions, however, differ. A survey conducted by the Insitute of Food Research in London showed people believe even the scientific community knows little about the potential dangers of genetic manipulation of plants and animals. On the other hand, respondents felt scientists better understood the risks due to alcohol, natural toxicants and even food irradiation. Nevertheless, when questioned about longterm effects, those interviewed felt pesticide residues in food were more dangerous than genetic manipulation of plants. And, they expressed even less concern about microwave cooking and caffeine.