Toxicology studies.
Animal models have been used to assess human health risk from consumption of products containing Cry proteins. The United States Environmental Protection Agency recognizes mouse acute oral feeding studies where doses as high as 5,000 mg/kg body weight resulted in no observed adverse effects.Research on other known toxic proteins suggests that toxicity occurs at much lower doses, further suggesting that Bt toxins are not toxic to mammals.The results of toxicology studies are further strengthened by the lack of observed toxicity from decades of use of B. thuringiensis and its crystalline proteins as an insecticidal spray.[citation needed]