As used in this act:
a. "Department" means the Department of Transportation;
b. "Hazardous material" means a substance or material determined by the Secretary of the United States Department of Transportation to be capable of posing an unreasonable risk to health, safety, and property when transported in commerce and so designated pursuant to the provisions of the "Hazardous Materials Transportation Act," Pub.L. 93-633 (49 U.S.C. s. 1801 et seq.).