title: Age-related differences in acute neurotoxicity produced by mevinphos, monocrotophos, dicrotophos, and phosphamidon.
abstract: Age-related differences in the acute neurotoxicity of cholinesterase (ChE)-inhibiting pesticides have been well-studied for a few organophosphates, but not for many others. In this study, we directly compared dose-responses using brain and red blood cell (RBC) ChE measurements, along with motor activity, for mevinphos, monocrotophos, dicrotophos, and phosphamidon. Long-Evans hooded male rats were tested as adults and at postnatal day (PND) 17; PND11 pups were also tested with dicrotophos only. All chemicals were administered via oral gavage and tests were conducted at times intended to span peak behavioral and ChE effects. All OPs tested produced a rapid onset and recovery from the behavioral effects. There were age-related differences in the inhibition of brain, but not necessarily RBC, ChE. Mevinphos was clearly more toxic, up to 4-fold, to the young rat. On the other hand, monocrotophos, dicrotophos, and phosphamidon were somewhat more toxic to the young rat, but the magnitude of the differences was < 2-fold lower. Motor activity was consistently decreased in adults for all chemicals tested; however, there was more variability with the pups and clear age-related differences were only observed for mevinphos. These data show that three of these four OPs were only moderately more toxic in young rats, and further support findings that age-related differences in pesticide toxicity are chemical-specific.
authors.affiliation: Neurotoxicology Branch, Toxicity Assessment Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development,US Environmental Protection Agency, Research Triangle Park, NC, USA. Moser.ginger@epa.gov
authors.forename: Virginia C
authors.initials: VC
authors.lastname: Moser
mesh_terms: D000375:Aging / Q000378:metabolism / Q000523:psychology; D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000201:enzymology; D002800:Cholinesterase Inhibitors / Q000633:toxicity*; D002802:Cholinesterases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000187:drug effects / Q000201:enzymology; D008297:Male; D008799:Mevinphos / Q000633:toxicity; D008999:Monocrotophos / Q000633:toxicity; D009043:Motor Activity / Q000187:drug effects; D020258:Neurotoxicity Syndromes / Q000209:etiology* / Q000503:physiopathology; D009943:Organophosphorus Compounds / Q000633:toxicity; D010575:Pesticides / Q000633:toxicity*; D010707:Phosphamidon / Q000633:toxicity; D051381:Rats; D020318:Rats, Long-Evans
chemical_list: D002800:Cholinesterase Inhibitors; D009943:Organophosphorus Compounds; D010575:Pesticides; D010707:Phosphamidon; D008999:Monocrotophos; D008799:Mevinphos; C000944:dicrotophos; D002802:Cholinesterases