The study of behavior change in response to drugs, chemicals, or other environmental conditions or agents (collectively referred to here as toxicants). Changes in behavior, as well as changes in sensation, mood, intellectual function, and motor coordination, are used by behavioral toxicologists to identify risks associated with exposure to potential toxicants and to determine mechanisms by which toxicants can affect the central nervous system. The information gained through behavioral toxicology can be used by scientists and government agencies to set limits in permissible levels of exposure to an environmental toxicant. Techniques employed in behavioral toxicology include epidemiologic surveys, field-based research, and laboratory-based experiments using human or nonhuman subjects.