ABSTRACT
This chapter explores a variety of local and systemic reactions elicited by chemical exposure and the physiological and immunological basis of those effects. The four types of immunological hypersensitivity reactions include typeI antibody-mediated reactions; type II antibody-mediated cytotoxic reactions; type III immune complex reactions; and type IV delayed-type hypersensitivity. Idiosyncratic reactions are abnormal responses to drugs or chemicals, generally resulting from uncommon genetic predisposition. An exaggerated response to the skeletal muscle relaxant properties of succinylcholine, a depolarizing neuromuscular blocker, classifies as a typical idiosyncratic reaction. In contrast to immune hypersensitivity reactions, some chemical effects are immediate or delayed, depending on the mechanism of toxicity. The acute effects of sedative-hypnotics are of immediate consequence; an overdose raises the risk of death from respiratory depression. Two or more chemicals whose combined effects are equal to the sum of the individual effects are described as having additive interactions.
