One of the main concerns of GM products is the effect on human health. There have been arguments from both sides of the debate, one claiming that GMOs are detrimental to the human body and one claiming otherwise, thus leading to mixed public opinion on whether or not GMOs should be allowed for human consumption. There is a fear that because some GM plants contain pest-killing toxins, that the toxins will harm humans too. However, the reality is that there is no such evidence that proves this, even with GM products having already existed on the market for over a decade. Some opponents also claim that genetic engineering has the ability to introduce allergens into plants that would not normally cause allergies in certain individuals. However, similar to the prior claim, there is no evidence that GM crops are any more allergenic than their non-modified counterparts.