It has been reported in the scientific journal Nature that in the USA a small amount of GM maize (Bt 11, produced by Syngenta) had been contaminated with another variety of unauthorised GM corn (Bt 10).

A Defra spokesperson commented:

"There is no actual indication that this contamination could have affected supplies of maize exported to the UK. The amount of seed in question is very small. In addition, only 18% of US corn is exported - and the EU imports only a very small proportion of US exports of maize. In addition this form of maize is used predominantly in animal feed rather than in food production. We do however apply high standards of enforcement and as part of our firm commitment to consumer choice and information we are making this information public."

Both Bt 11 and Bt 10 are transgenic lines of maize containing the same GM event. Both plants are resistant to the corn borer, which is a pest which affects maize. Consent for import of Bt 11 maize grain into the EU was issued by UK Competent Authority in June 1998 under Directive 90/220/EC. Bt 10 is an unauthorized transgenic line.

Syngenta informed Defra and the Food Standards Agency yesterday (22 March) that planting of Bt 10 maize occurred in the US on a small scale, primarily at a pre-commercial development stage. Planting of these GM maize plants was on a very small scale in the US and therefore the contamination of Bt 11 maize grain by Bt 10 grain will also be on an extremely small scale.

We understand the US food safety authorities have assessed the current report of the incident. Both GM events produce the same protein and therefore Bt 10 is covered by the existing tolerance exemption for Bt 11. The USDA has therefore concluded that they have no safety concerns.

Food or feed derived from a mixture of Bt 11 and Bt 10 maize seeds would not reveal the two original sources of Bt protein as they are identical.