TYPES OF GMOs
Crops are genetically engineered to carry a gene from the soil bacterium Bacillus thuringiensis (Bt). The bacterium produces proteins that are toxic to some pests. It kills them by creating holes in the walls of their digestive tracts. The biotech industry and regulatory agencies allowed this toxin into the human food supply based on the assumption that Bt-toxin is harmless to humans and other mammals. Peer reviewed published research, however, confirms that Bt-toxin produced in GMO corn can create the same type of holes in human cells, when applied in large concentrations in a laboratory. Bt crops fed to lab animals caused damage to the intestinal walls. Further, research on the natural toxin produced by soil bacteria elicits immune and allergic responses in humans and rodents. Numerous reports from India, including case studies by physicians, also document that people exposed to Bt cotton in the field, to bundles of harvested Bt cotton, and in cotton cleaning facilities, develop allergic and flu-like symptoms. These same symptoms were reported in published research describing the side-effects of spraying natural Bt-toxin in the Pacific Northwest of the US and in BC Canada.
The Bt-toxin produced in GMO crops is intentionally altered to be more immediately toxic than the spray form. It is also produced in crops at a concentration that is thousands of times that which is used in natural sprays. And whereas natural sprays wash off in the rain and biodegrade in sunlight, the Bt-toxin in crops remains encapsulated.
The biotech industry claims that Bt crops can reduce the need for applications of chemical insecticide by farmers. Research on GMO corn and cotton have shown that in the first few seasons this can be true. But due to the presence of new non-target insects that are not susceptible to Bt-toxin, and due also to the increased tolerance among the target insects, farmers often end up spraying more chemical insecticide on Bt crops than the non-GMO crops.
Furthermore, even when there is a reduction of chemical sprays in the initial seasons, the amount of Bt-toxin produced in the field by the crops adds up to far more insecticide per acre than the amount of chemical spray displaced. The disparity is even greater when you add the neonicotinoid insecticide seed treatments added to most GMO seeds.
Numerous studies on Bt crops demonstrate significant harm to the environment.
The three types of Bt crops currently commercialized are corn, cotton and, in South America, soy. Bt eggplant is being grown in Bangladesh. 
Most GMOs have been developed to survive application of herbicides. Inserted bacterial genes allow the herbicides to be applied to the crop to kill the weeds in the field without damaging the crop itself. An example would be Roundup Ready crops.
Unfortunately, Roundup’s chief poison glyphosate is absorbed into the plant and ends up in the food we eat. There are numerous studies showing significant health damage linked to even tiny amounts of glyphosate and Roundup.
Roundup also damages the environment, according to a large number of studies.
The herbicide tolerant crops have also increased the use of the associated herbicide. First, farmers spray over the entire field instead of spot spraying. Second, weeds have developed tolerance to the weed killer, resulting in farmers using more concentrated mixtures and spraying more and more times during the growing season.
Herbicide tolerant crops currently on the market include soy, corn, cotton, canola, sugar beets, and alfalfa. 
Genome Editing (Gene Editing):
Genome editing is a method that lets scientists change the DNA of many organisms, including plants, bacteria, and animals. Editing DNA can lead to changes in physical traits, like eye color, and disease risk. Scientists use different technologies to do this. Example is the Crispr technology which produced the non- browning apple.
The biotech industry has initiated a global campaign to convince regulators and the public that gene editing is so safe and predictable, no regulation or government oversight is needed. Nonetheless, there is now overwhelming evidence that the technology does consistently create unpredictable side effects that can be dangerous to health and the environment. 
GMO papaya from Hawaii or China, zucchini, and yellow squash, have all been genetically engineered to resist specific plant diseases. Scientists have expressed alarm that there are numerous ways that these foods might cause health problems, yet no meaningful safety studies have been conducted. 
Scientists can design and construct new biological parts, devices and systems, such as synthesizing a new sequence of DNA and insert it into a cell that has had its own DNA removed. Scientists also engineer microorganisms, such as bacteria and yeast with additional genes. These genes create proteins that are then used in products, including food and medicine.
In the 1980s, a Japanese corporation used GMO bacteria to create a health supplement L-tryptophan that killed about 100 Americans and caused 5,000-10,000 to fall sick or become permanently disabled.
Other food products on the market that are produced with GMO bacteria or yeast include aspartame, Impossible Burger, and vanilla. Recombinant bovine growth hormone (rBGH) is also produced using this method. 
Gene Silencing or RNAi:
Short strands of RNA have the ability to silence or alter the activity of genes. Some GMOs are engineered with genes designed to create such RNA, which in turn will silence a gene. Examples include the non-browning potato and apple.
Numerous scientists, including some who worked at the USDA and EPA, have expressed concern because research suggests that the RNA mechanism can alter “non-target” organisms. In other words, plant pests, animals, and even humans that consume these GMOs may experience altered gene expression. Unfortunately, no research has been conducted on the GMO apples and potatoes to rule this out. 
See our GMO 2.0 campaign called Protect Nature Now for descriptions of other types of GMOs under development, including Gene Drives, RNAi sprays, altered insects, etc.
Download a PDF of the full GMO Myths and Truths report here.
- Smith, Jeffrey M. (2007). Genetic Roulette: The Documented Health Risks of Genetically Engineered Foods. Yes! Books.
- What is genome editing? Retrieved from https://www.genome.gov/about-genomics/policy-issues/what-is-Genome-Editing
- What is Synthetic Biology? Retrieved form https://www.synbioproject.org/topics/synbio101/definition/
- (2013). How RNAi Works. Retrieved from https://www.umassmed.edu/rti/biology/how-rnai-works/