For crops including cotton, soybean, and maize they have already become standard in North America. The advantages of the crops include disease resistance, insect resistance, altered or novel products such as oils, different varieties, and tolerance of adverse soil, water and environmental conditions. Reductions in the use of chemical pesticides are also associated with some of these varieties. However, there are concerns whether the introduced genes might transfer to other species, and whether this might cause harm to those species or adversely alter the ecosystem. This has been called genetic pollution, and scientific experiments found generally the probabilities of adverse events occurring are low, but that this varies between species.
Continual monitoring is called for, and food safety tests to monitor allergies and side effects.
Animal rights Concurrent with the emergence of bioethics has been the modern animal rights movement, which has led to reduced use of animals for toxicity testing and research, as well as even violent protests against research that continue to use animals. Understanding of evolutionary links and the common gene pool has also increased the arguments to regard non-human animals as ethical beings in their own right, a biocentric approach to viewing life. Alternative tests have been devised which may not involve animals, or reduce the number of animals used and the pain and suffering to the animals. Technology has allowed development of cell lines which can be used instead, or genetically modified animals, especially transgenic mice, that have increase susceptibility to develop cancer less animals are needed. Cloning of genetically identical animals to be used for control and test animals can also reduce numbers.