Neurobehavioral toxicology of pyrethroid insecticides in adult animals: a critical review.

Pyrethroids are pesticides with high selectivity for insects. In order to identify strengths and gaps in the database for pyrethroid neurobehavioral toxicology, we have critically analyzed the data from peer-reviewed literature. This review includes dose-response data that have been recently generated demonstrating consistent findings for low-dose, acute, oral exposure to pyrethroids in small rodents. All pyrethroids tested (i.e., about twenty compounds), regardless of structure, produce a decrease in motor activity in a variety of test protocols. The range of relative potencies varies more than two orders of magnitude, and thresholds for motor activity were found well below doses that produce overt signs of poisoning. Six compounds (allethrin, permethrin, cis-permethrin, deltamethrin, cypermethrin, and fenvalerate) impair schedule-controlled operant responding, seven compounds (pyrethrum, bifenthrin, S-bioallethrin, permethrin, beta-cyfluthrin, cypermethrin, and deltamethrin) decrease grip strength, and two compounds (deltamethrin and alpha-cypermethrin) produce incoordination using the rotarod. In addition, while compounds lacking an alpha-cyano group (e.g., cismethrin, permethrin, bifenthrin) induce an increase in acoustic-evoked startle response amplitude, cyano compounds (e.g., deltamethrin, cypermethrin, cyfluthrin) produce the opposite outcome. Other endpoints (e.g., tremor intensity, sensory response) have been only occasionally explored. A synthesis of the neurobehavioral evidence relating to the action of pyrethroids indicates that some differences in the experimental findings across compounds are also present in the low-effective dose range. For risk assessment purposes, a strategy that takes into account data from an array of neurobehavioral endpoints is needed to capture the heterogeneity of pyrethroid-induced adverse effects and accurately inform policy decisions.

Paranasal sinus aspergillosis.

Four cases of aspergillosis of the paranasal sinuses seen recently at the North Carolina Baptist Hospital are reported. Paranasal sinus aspergillosis is prone to develop in patients living in the southeastern states because those states 1. have an agricultural economy and 2. have a hot, humid climate that causes a high incidence of nasal and sinus disorders. The increasing use of immunosuppressive and oncological drugs should further increase the incidence of aspergillosis. Diagnosis of aspergillosis of the paranasal sinuses requires a high index of suspicion which should be present particularly for a patient who has unilateral sinusitis that does not respond to routine therapy, or who has a localized sinus mass or bony erosion. Immunodiffusion tests are specific for aspergillosis. Treatment consists of surgical removal of the diseased mucosa and adequate aeration and drainage of the sinus. Culture of the specimen on Sabouraud's agar will confirm the diagnosis.