Summarize the concerns related to the use of transgenic crops.

Most food from transgenic crops contains one or more proteins encoded by transferred genes. Are foods containing the new proteins safe to eat? In general, if the proteins are not toxic or allergenic and do not have any negative physiological effects, they are not considered a significant health hazard by regulatory agencies. In the case of herbicide-tolerant food plants, the enzyme produced by the transgene is readily degraded in digestive fluids, is nontoxic to mice at doses thousands of times higher than any potential human exposure, and has no similarity to known toxins or allergens. After almost 20 years of widespread use, no human health risks from transgenic plants have been demonstrated. Several potential environmental risks associated with transgenic crops have been identified, including transfer of herbicide resistance or insect resistance from crop plants to weeds and wild plants, loss of biodiversity caused by transgenic plants hybridizing with wild varieties of the same species, and possible deleterious impacts on ecosystems. However, most of these problems are identical to those we face in using conventional crop plants modified by artificial selection, and there is no current scientific evidence that transgenic crops are inherently different from crops developed by artificial selection. Transgenic crops have a different evolutionary history and are genetically different from conventional crops, but there are no demonstrated ecological or environmental risks unique to transgenic crops. However, as the modification of crop plants becomes more complex, some combinations of traits may be generated that may require specific crop-management procedures.