Evidence for specific hazards within each of these categories is growing. Environmental risks include spread of engineered genes to related plants, effects on non-target organisms, and the development of resistant pests. Research has shown, for example, that herbicide tolerance can be transferred from canola to related weedy species. Insect resistance to genetically engineered Bt crops is a well-recognized problem. Health risks include allergic response, the introduction of new toxins and pathogens, and antibiotic resistance.
Genetic engineering enables the introduction of new proteins into food.
The toxicity and allergenicity of these proteins can only be assessed through direct laboratory testing. Many genetically engineered crops also contain genes that code for resistance to antibiotics. These genes may be inadvertently transferred to micro-organisms, making them, and the diseases they cause, more difficult to control. In addition, research on genetically engineered plants containing viral genes has shown that these genes can combine in the plant with other viral strains to produce new pathogens. Indeed it does.