The study believes that maize has emerged as the ideal candidate to be developed commercially as a vehicle for antibody production. The plant's physiology, widespread cultivation and genetic diversity make it ideal for molecular agriculture.

Along with maize, tobacco oilseed rape and soya have become the popular choices for pharma companies. Products such as blood and blood coagulation proteins, vaccines, collagen-like substances, antimicrobial and antiviral substances, growth hormones, various enzymes and especially antibodies can be produced in significant quantities.

Writing in the Plant Science review, scientists from the University of Lleida believe that the genetic modification of plants for the production of protein-based drugs is useful for the treatment, prevention and early detection of human and animal diseases, as well as for the production of vaccines against tuberculosis, diabetes and rabies.

"A more practical and productive approach to evaluate the ecological and toxicological risks, in which a scientific problem refers to a significant, final evaluation, and the hypotheses of risk predict effects in which the final evaluation is not a transformed plant, but the product resulting from that plant," said head scientist Paul Christou.

The study was quick to point out the safety concerns of using maize not just for humans but for the environment, citing the gene flow throughout the plant's life cycle, and the potential impact on the health of animals and humans through inadvertently consuming this crop.

The main issue these plants raise is that they are used specifically to produce substances that have an effect on humans or on higher animal species. They are also optimised in terms of yield.

In other words the amount of active substance they produce is many times that produced in previous GM plants, and several genetic modifications are often carried out at once. In other words to make the plants sterile for safety reasons, the likelihood of unforeseen impacts is all the greater.

"The gene flow per se should not be considered "bad" for the environment," said Christou.

He said that should this be developed on a commercial basis, all pharmacological production of maize will be undertaken in specialised locations, "where any risk of gene flow will be unlikely."

Producing drugs using biotechnology is not new, but have been restricted to production within closed systems using microbial, animal and occasionally plant cells or tissue.

These drugs (biopharmaceuticals) are produced by inserting the genes that code for the desired substance into the production organism and expressing them there. Nearly two-thirds of licensed drugs produced using biotechnology are produced in Escherichia coli, including human insulin, a recombinant drug that was first produced in 1982.

Seven of the 50 top-selling drugs in 2003 were biopharmaceuticals. They currently account for around seven per cent of the global pharmaceuticals market.

The study: 'An ideal production platform for effective and safe molecular pharming,' appears in the latest edition of Plant Science.