UTILITY OF A NEUROBEHAVIORAL SCREENING BATTERY FOR DIFFERENTIATING THE EFFECTS OF 2 PYRETHROIDS, PERMETHRIN AND CYPERMETHRIN

The ability of a neurobehavioral screening battery to differentiate th e effects of two pyrethroids, permethrin and cypermethrin, was assesse d in this experiment. Although the structures of these pesticides diff er only in the alpha-cyano group, the behavioral syndromes associated with the Type I and II pyrethroids are quite different. The tests incl uded a functional observational battery which is a series of subjectiv e and quantitative measures of neurological function and behavior, and an automated measure of motor activity. Our results verified previous reports in the literature describing these different syndromes, i.e., aggressive sparring behavior, fine to whole-body tremor, hyperthermia , and decreased motor activity for the Type I pyrethroid permethrin, a nd pawing, burrowing, salivation, whole body tremor to choreoathetosis , hypothermia, and lowered motor activity for the Type II pyrethroid c ypermethrin. In addition, we report that permethrin produced decreased grip strengths, increased resistance to capture, increased reactivity to a click stimulus, and induced head and forelimb shaking and agitat ed behaviors, whereas cypermethrin produced pronounced neuromuscular w eakness and equilibrium changes, retropulsion, lateral head movements, alterations in responses to various stimuli, and increased urination. Although there were similarities in some effects (e.g., decreased mot or activity), the pesticides differed sufficiently in their overall be havioral profiles, and severity and time course of effects, to discrim inate these two compounds. Thus, this type of screening approach is se nsitive enough to differentiate these pyrethroids for hazard identific ation purposes.