Comparison of chlordimeform and carbaryl using a functional observational battery

The effects of the formamidine pesticide chlordimeform (CDM), and the carbamate carbaryl (CAR) were compared using a functional observational battery (FOB). The FOB, a series of observations and measurements that can be rapidly administered to toxicant-treated rats, includes home-cage and open-field observations, neuromuscular and sensorimotor tests, and physiological measures. Evaluations were made according to U.S. Environmental Protection Agency testing guidelines so as to determine dose-, time-, and sex-related toxicant effects. Long-Evans hooded rats of both sexes were tested initially and then dosed ip with either vehicle, CDM (1, 25, 56 mg/kg) or CAR (3, 10, 30 mg/kg), and tested at various times after dosing (for CDM 1, 5, 24 hr; for CAR 0.5, 3, 24, 48 hr). Both compounds affected general activity (home-cage and open-field), equilibrium, CNS excitability, and sensory responsiveness. Whereas similar decreases were obtained on rearing, gait, and arousal, there were important qualitative differences in the effects of CAR and CDM on reactions to handling and the reflex tests in that CDM increased excitability and enhanced responses to several stimuli but CAR either had no effect or decreased these measures. Only CDM produced an increase in muscle tone as measured by grip strength, and only CAR produced cholinergic autonomic signs of intoxication. Body weight and temperature were decreased by both compounds. Thus, the profiles of effect produced by these two pesticides could be clearly differentiated using the FOB.