Tennessee Code Title 7. Consolidated Governments and Local Governmental Functions and Entities § 7-51-205

(a) For the purposes of this section, “firefighter” means any regular and full-time employee of a county with a metropolitan government with a population of four hundred thousand (400,000) or more, according to the 1980 federal census or any subsequent federal census, who is required to extinguish and control fires or fire-related incidents and other employees of fire departments who are required to perform their duties under and in a toxic environment.

(b) Any county with a metropolitan form of government with a population of four hundred thousand (400,000) or more, according to the 1980 federal census or any subsequent federal census, that maintains a regular fire department manned by regular and full-time employees, and has established or hereafter establishes any form of compensation, other than workers' compensation, to be paid to such firefighters for any condition or impairment of health that results in loss to life or personal injury in the line of duty or course of employment, may establish by ordinance a presumption that any impairment of health of such firefighter caused by disease or cancer resulting in hospitalization, medical treatment or any disability, shall be presumed, unless the contrary is shown by competent medical evidence, to have occurred or to be due to accidental injury suffered in the course of employment. Any such condition or impairment of health that results in death shall be presumed, unless the contrary is shown by competent medical evidence, to be a loss of life in the line of duty, and to have been in the line and course of employment, and in the actual discharge of the duties of such firefighter's position, or the sustaining of personal injuries by external and violent means or by accident in the course of employment and in the line of duty; provided, that such firefighter shall have successfully passed a physical examination prior to such claimed disability, or upon entering upon such firefighter's metropolitan government employment, and such examination fails to reveal any evidence of the condition of cancer.