PESTAB. Chemicals used in pest control have a wide range of chemical structures, from simple mixtures of copper, mercury, and arsenic salts to complex cyclic and polycyclic compounds. Molecular mechanisms of action are discussed for insecticides; herbicides, and fungicides. Organophosphate and carbamate insecticides act by inhibiting the active site of acetylcholine esterase, a neurotransmitter. Herbicides generally inhibit enzymes involved in photosynthesis. Fungicides act by chelating certain metal ions or interfere with fungal metabolism. Effects of these biocides in nontarget mammals may vary with the sex and general health of the organism. The major biotransformation reactions to which pesticides are subjected are dehydrohalogenation, dehalogenation, desulfuration, epoxidation, hydrolysis, hydroxylation, isomerization, N-desalkylation, O-desalkylation, oxidation, and reduction. The biodegradation of pesticides, particularly systemic pesticides that persist in the environment, needs further study.
