Carbon blacks differ from the general class of soots in identifiable chemical and physical respects, and inferences based on studies with soots, especially in the field of health effects are inappropriate for extension to carbon blacks. Carbon black is typically 99% colloidal particulate carbon of a grape cluster morphology (Anciniform). Soot, on the other hand, is a complex mixture of particulate carbon, soluble organic material, insuluble organic material and ash. Table and text break down different classes of soot and comment on posssible health effects. -- AATA