SOME COMPARATIVE TOXICOLOGIC AND PHARMACOLOGIC EFFECTS OF DIMETHYL SULFOXIDE AS A PESTICIDE SOLVENT

The acute oral and intraperitoneal toxicities of dimethyl sulfoxide (DMSO), dimethyl acetamide (DMA), dimethyl formamide (DMF), and propylene glycol (PG), diluted and undiluted, were compared in rats after 24-hr. and 5-day periods. DMSO is less toxic than DMA and DMF. The toxicities of DMSO and DMF were unchanged by dilution with water. A delayed toxicity was noted with DMSO, DMA, DMF, and PG by each route. None of these solvents influenced brain cholinesterase activity. Some significant differences in the inhibition of cholinesterase by carbaryl in various solvents were observed. The acute oral toxicities of thiram, dieldrin, carbaryl, MC-A-600 [4-benzothienyl-N-methyl carbamate], and parathion were generally similar whether administered in DMSO, in corn oil, or as an aqueous suspension. Some differences in the times of the onset of signs of toxicity were noted. Undiluted DMSO produced a depression of spontaneous motor activity without an effect on hexobarbital sleeping time or the conditioned avoidance response. The depression was abolished by dilution. Because of the low acute toxicity and apparent lack of interaction, DMSO is a useful solvent for studying the effects of pesticides in animals.