A waste is considered hazardous if it exhibits any of four characteristics-reactivity, corrosivity,
ignitability, or toxicity. Of these, the potential for toxicity, both to humans and to other biota
(ecotoxicity), has caused the greatest public concern and has prompted massive regulatory initiatives
in hazardous waste management. It follows that the management of hazardous waste has as its
fundamental objective the protection of human and ecological health_by reduci!lg the risk, if not the
toxicity, of the substances in hazardous wastes to acceptable levels. An understanding of toxicology is
therefore needed to determine whether the management of hazardous waste or the remediation of
contaminated sites meets this objective.
Chapter 4 covered the fate and transport of substances from their release into the environment
up to their contact with receptors. This chapter addresses the toxic effects caused by hazardous
substances on gaining access to the human body and other living organisms. Toxic effects can range
from mild allergic reactions to death. Indeed, the constituents of some hazardous waste can kill
humans outright as evidenced by graphic accounts. Some constituents can cause death in insidious
ways such as cancer.