Controversial issues related with the use of genetically modified food

Allergies
Crops are being modified basically to improve the nutritional value of a food. However the foreign genes that are inserted on these crops may cause allergies to some people due to the ineffectiveness of the antibodies to defence against any attack. Food that are genetically engineered contain trace amount of protein which will trigger allergic reactions. For example Soybean has been modified using genes from the Brazil nut that contain methionine which are lacking in soybean and thus causing allergic reaction on these people that are allergic to Brazil nut.
Reference: Stephen Nottingham. 1998, Eat your genes: how genetically modified food is entering our diet, Zed Books Ltd.
Environmental impact
~Biodiversity
There is a threat that this genetically modified food may spread their genes through breeding, to other crops containing their altered genes. Thus this will have an impact on the ecosystems.

Reference: http://www.princeton.edu/~chm333/2002/spring/GMFoods/impactsenvironmentcons.html
~Super weeds
The spread of GM pollen might also lead to cross pollination with other crops. If this GM trait is to pick up by this crop, it might take over the ecosystem destroying other crops causing loss of biodiversity. These superweeds are herbicides-resistant and are not easy to be removed.
Reference: http://www.princeton.edu/~chm333/2002/spring/GMFoods/impactsenvironmentcons.html
Ethics
~Destruction of natural organisms' intrinsic values
~Tampering with nature by altering genes among species
~Objections to consuming animal genes in plants and vice versa especially in vegetarians
~Stress for animal
Labeling
~Not compulsory in some countries (e.g., United States)
~Some manufacturer fails to label food that is genetically modified thus confusing people between foods that are natural and food that are engineered.
Society
~The rich become richer and the poor become poorer
Available at: http://www.ornl.gov/sci/techresources/Human_Genome/elsi/gmfood.shtml (accessed 15 June 2008)

Regards
Aziyani