ARCHIVED - Information: Safety Assessment of Genetically Modified Corn

April 1997

After careful assessment, Health Canada has concluded that corn that has been genetically altered to make it resistant to certain insect pests is no different in composition or nutritional quality than other commercially available corn varieties, and that it is suitable for food use. Consequently, Health Canada has notified Ciba Seeds that it has no objection to the sale of this corn in Canada.

The corn has been genetically modified to protect it against insect pests, particularly the European Core Borer (ECB), a major insect pest in corn agriculture.

Ciba Seeds has synthesized a gene, the Bt gene, that contains a truncated form of an insect-control protein from Bacillus thuringiensis subspecies kurstaki (B.t.k.). When the gene is inserted into field corn, the corn produces the insect-control protein in its leaves and pollen, which ECB larvae feed upon. The insect gut processes the protein similarly to the insecticidal protein produced by B.t.k. in nature and in pesticides based upon B.t.k, and the insect is killed. This development permits producers to reduce their use of pesticides, which can leave chemical residues in the environment and on the corn.

A second gene has also been inserted into the corn to express a protein, phosphinothricin acetyltransferase (PAT). This protein is an enzyme that acts as a biological marker to allow researchers to identify the modified plants.

The insect-control protein is produced in very small quantities in corn leaves and pollen; most other plant tissues, including kernels, have barely detectable levels of the protein. Both the insect-control protein and the PAT protein are expected to be destroyed during the processing of grain into food products. Digestibility studies have shown that, in the unlikely event that any proteins persist, they will be digested as conventional dietary protein. Acute oral toxicity studies in mice and birds indicated no effect from either the insect-control protein or the PAT protein. Comparisons of the insect-resistant corn with other commercial corn varieties found no difference in the concentration and bioavailability of nutrients.

Health Canada's assessment of the insect-resistant corn was conducted according to the Guidelines for Safety Assessment of Novel Foods (September 1994). These guidelines are based on internationally accepted principles for establishing the safety of foods derived from genetically modified organisms, and were developed in consultation with other government agencies, consumers, and industry.

This assessment relates only to the food use of the insect-resistant corn. Issues related to growing this corn in Canada are being addressed separately through existing regulatory procedures in Agriculture and Agri-Food Canada.

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