Those who oppose genetically modified food involve a wide range of interest groups, from Greenpeace to farmers' associations to Christian churches, and so on. Their opposition is concentrated in three areas:
First, genetic modification is against nature and therefore harmful. The supporters retort that today's crops are no longer primitive varieties, otherwise the vegetables that people eat should be the same as the grass that animals eat.
Second, after genes with herbicide resistance or toxic pest-killing functions are introduced into plants, are the food they provide safe for humans? In response to this point, the supporters emphasized that until now, no qualified research institutions have found evidence that genetically modified foods harm human health, but their long-term impact can only be inferred, and it is difficult to obtain comprehensive evidence to convince people.
Third, is it possible that the promotion of genetically modified plants too hastily affects agriculture and the ecological environment? The promotion of genetically modified crops that are resistant to herbicides may encourage farmers to overuse herbicides, causing some non-main crops to be harmed or even extinct. Many farmers in developing countries have been using such non-main crops as supplementary food or as feed. The U.S. Fisheries and Wildlife Administration has discovered that 74 plant species are affected by herbicides and are endangered.