The number of additional toxicological studies required will depend on the classification of the GM food or GM food components.

In the case of GM food or GM food components identified as substantially equivalent to their traditional counterpart, further toxicological information is not required. In all other cases the nature and extent of additional studies should be carefully selected, taking into account the source and composition of the GM food, its potential intake and whether it is intended for a specific application or for more general use in the diet.

For GM food or food components classified as substantially equivalent to existing foods or food components except for defined differences, the toxicological evaluation should focus on the identified differences between the GM food and its traditional counterpart.

For GM foods or food components which are not substantially equivalent to existing foods or food components, a broader range of tests is likely to be required than for other GM foods.

Allergenicity

The assessment of the allergenic potential of a GM food is an important part of toxicological testing. Allergenicity involves a limited number of individuals, and tests exist to identify proteins, which can cause adverse reactions. However, there is no valid test to predict the allergenic potential of a protein which is not commonly recognised as an allergen.

If the GM food contains genes which are known to have a relation to allergenicity, a series of special chemical and immunological tests are required to identify the proteins, which cause the allergenic reaction. These in vitro tests have to be confirmed by in vivo tests. In any case, the new food should be labelled to inform the consumer that traces of an allergenic protein could be included.

If it is not possible to identify potential allergens by comparing it with a traditional food, a different method has to be used. Proteins often fulfil one or several specific criteria, including stability to heat, molecular weight and effect of pH.

It is not possible to predict in advance if the GM food has an allergenic potential or not. Therefore, strict test-marketing strategies and a post-marketing surveillance procedures are crucial.