Neurotoxicity of the pesticidal carbamates

The carbamates, stabilized derivatives of carbamic acid, are potent biological agents used extensively in applications ranging from agriculture to medicine and industry. This review covers the two major classes of pesticidal carbamates: (1) cholinesterase-inhibiting carbamates which include monomethyl- and dimethylcarbamates (used primarily as insecticides); and (2) non-cholinesterase inhibiting, sulfur containing carbamates, the dithiocarbamates (used primarily as fungicides and herbicides). The dithiocarbamates include four major classes; (a) methyldithiocarbamates, (b) dimethyldithiocarbamates, (c) diethyldithio carbamates, (d) ethylenebisdithiocarbamates. For the purposes of this review neurotoxicity is defined as any unwanted change in the functional status of the organism which can be characterized in terms of behavioral, neurochemical, electrophysiological, or neuropathological indices. Neurotoxicity associated with methyl- and dimethylcarbamates has been characterized in terms of their reversible cholinesterase-inhibiting properties. The dithiocarbamates can have neurotoxic effects. However, a complete characterization of the neurotoxicity of these compounds has not been attempted. The neurotoxic actions of the dithiocarbamates may be related to their metal-chelating and enzyme-inhibiting properties.