a field of medicine that studies poisonous (toxic) substances, the potential danger of their effects on organisms and ecosystems, mechanisms of toxic action, as well as methods of diagnosis, prevention, and treatment of diseases developing as a result of such exposure. Behavioral toxicology as a branch of toxicology studies changes in human behavior under the influence of substances contained in the environment. For example, early symptoms of mercury poisoning in humans include irritability, anxiety, insomnia, timidity, and emotional instability.