Hazardous materials are any solid, liquid, or gaseous material that, because of quantity, concentration or physical, chemical, or infectious characteristics, may (a) cause or significantly contribute to an increase in mortality or an increase in serious irreversible or incapacitating illness, or (b) pose a substantial present or potential hazard to human health or the environment when improperly treated, stored, transported, disposed of or otherwise managed.
"Hazardous Materials" means (i) any substance, emission or material including, but not limited to, asbestos, now or hereafter defined as, listed as or specified in a Applicable Law as a "regulated substance," "hazardous substance," "toxic substance," "pesticide," "hazardous waste," "hazardous material" or any similar or like classification or categorization under any Environmental Law including by reason of ignitability, corrosivity, reactivity, carcinogenicity or reproductive or other toxicity of any kind, (ii) any products or substances containing petroleum, asbestos, or polychlorinated biphenyls or (iii) any substance, emission or material determined to be hazardous or harmful.
"Any substance that can threaten health, safety, and property being transported" (see full definition at The Law Dictionary).
"A number of terms (e.g., "hazardous chemicals," "hazardous materials," "hazardous waste," and similar nomenclature) refer to substances that are subject to regulation under one or more federal environmental laws. State laws and regulations also provide additional, similar, or identical terminology that may be confused with the federally defined terms. Many of these terms appear synonymous, and it is easy to use them interchangeably. However, in a regulatory context, inappropriate use of narrowly defined terms can lead to confusion about the substances referred to, the statutory provisions that apply, and the regulatory requirements for compliance under the applicable federal statutes."
Read more about 'Hazardous Terminology' in the U.S. Department of Energy's CERCLA Information Brief EH-231-003/0191, which provides regulatory definitions and references for the precise terminology that should be used when referring to "hazardous" substances regulated under federal environmental law.