That is a question we are asked often.
When we launched a campaign in Quebec in favour of mandatory GMO labelling, we asked Université de Montréal researchers what studies had been published on the consequences of such a measure on the cost of food. There are no studies that have shown that the cost of a basket of groceries would increase.
In the United States, the industry fought for years to prevent mandatory GMO labelling, because it felt that this would increase its production costs enormously and that consumers would suffer the consequences in increased food costs.
However, since Vermont introduced mandatory GMO labelling last July 1, companies like Campbell's and Kellogg's, who are giants in the food industry, have adapted and begun to change their packaging. In fact, they began this process even before mandatory labelling became law in Vermont. Company representatives told us openly that this was not more costly, and that they changed their packaging on a regular basis in any case to adapt to consumers' tastes, and that they would not see an increase in food costs.
In short, the cost of food has not increased since Campbell's and Kellogg's took those steps. Consequently we doubt that consumers would see any significant increase in the cost of food.