Scientific knowledge is not an absolute. It is almost certain that what is known now, will be modified by scientists of the future.

Scientific knowledge, then, is no more than an interpretation of facts assembled at any one time. It is applied and, naturally, mistakes are made but we learn from them, rectify them and move on.

Changing the characteristics of an organism by altering its DNA, however, is a dangerous science because we cannot foresee the consequences.

The potential for disaster is too great and impossible to reverse.

On the face of it, genetic engineering offers much faster and more precise methods of breeding crops than conventional methods.

Food can be modified so it tastes better and stores longer. Some insist that GM food is a solution to world hunger because crops have heightened resistance to pests and disease.

They claim such crops may also lessen the need for pesticides and chemicals. So what are the perceived risks?

Until now, farmers have always selected their best plants as a source of seed for their next crop. They have freely exchanged information and material, encouraging biodiversity of many different plant species.

Farmers improve their techniques from generation to generation and, as a result, crops have adapted to heat, storms and flash floods in different climates.

Organic farming has sustained our soil and helped us survive for thousands of years and we ought to know by now it is quite safe.

We can't yet tell with GM foods. There is little doubt that if genetic material is transferred between animal and plant species, bypassing the natural process of evolution, our ecosystem will change in a way we cannot foresee.

Micro-organisms could mutate rapidly, behaving in unexpected ways. Genetically engineered crops which produce their own pesticides force pests to develop resistance but may harm other creatures such as ladybirds, bees, birds and frogs.

Weeds are likely to be contaminated by GM crops, creating "superweeds" which require higher levels of herbicides.

Conveniently, Monsanto sells not only herbicide-resistant GM seeds but matching herbicides as well.

World hunger isn't caused by a lack of GM foods but a lack of money and having to live in extreme climates or unfair economic and social conditions. Genetic engineering could make these problems even worse.

Much of the genetic food technology is owned by a handful of conglomerates which dictate what sort of crops are grown and attempt to stop farmers from saving and exchanging seeds, therefore preventing self-reliance and encouraging dependency.

Independent studies pointing to the considerable risks of GM foods to our immune systems are swept aside as irrelevant compared to the "improvement" offered by science.

But then, wisdom requires a degree of humility for which neither scientists nor politicians who set the agenda for big business are particularly renowned.

Many of them seem mesmerised by an illusion as well as by profits and one can't help wondering whether we are entering a Brave New World or the new Dark Ages.

Martina is a qualified nutritionist at the Crescent Clinic of Complementary Medicine, 37 Vernon Terrace, Brighton. Tel: 01273 202221 or email: