GM seed producers, such as Bayer, go through lengthy testing with regulators to prove the safety of their GM product for humans, animals and the environment before being authorized to sell such GM seed by regulatory agencies such as the Environmental Protection Agency, Food and Drug Administration and/or U.S. Department of Agriculture. Since the first plantings of commercialized GM seed in 1996 (19 years ago), it has not been proven to cause harm. Growers are free to choose the seed they wish to purchase and grow based on preference, regulations, agronomic considerations, etc. If, for instance, a grower of a non-GM crop does not wish to have pollen from a GM crop grown on an adjacent farm cross-pollinating their crop, there are some best management considerations that facilitate such coexistence, including spatial, temporal and/or physical isolation.
In the very unlikely event that a GM crop would be proven to cause harm, Bayer has an emergency contact number and has an established procedure to address and manage issues. Further recourse to national laws and even international environmental protection laws exists. If you still have questions, please ask.