title: Toxicity of 2-methyl-5,6-cyclopentapyrimidine (MCPP).
abstract: 2-Methyl-5,6-cyclopentapyrimidine (MCPP, CAS No. 36274-29-0) is a white dusty solid with a powerful lingering odor and is formed as a by-product in the polymer synthesis of an experimental polymer. The acute toxicity following both oral and inhalation exposures and the effects of repeated inhalation exposures in rats were determined. Mutagenic activity was assessed using Salmonella as the indicator organism. The chemical is moderately toxic, with the lethal dose following a single oral administration being 90 mg kg-1. Doses greater than or equal to 130 mg kg-1 produced strong convulsions. Excessive salivation, hyperactivity and twitching were seen at 90 mg kg-1 and only mild initial weight loss was seen in surviving rats (less than or equal to 60 mg kg). Liver injury was produced at doses as low as 17 (but not at 12) mg kg-1. The material was highly toxic by inhalation, with the approximate lethal concentration in rats following single 4-h exposures being 9 ppm. Convulsive-like movements were seen at greater than or equal to 9 ppm (not at 2 ppm). Histological findings suggest that MCPP causes dilation of blood vessels with hyperemia of various organs apparent in rats exposed to 1 ppm and sacrificed 1 or 2 days post-exposure. No evidence of liver or central nervous system damage was seen. Repeated (nine daily 4-h exposures) inhalation of 2 ppm MCPP failed to produce any signs of a toxic response. No mutagenic activity was seen. The material needs to be considered as a potent acute toxin.
authors.affiliation: E. I. Du Pont de Nemours and Co., Inc., Haskell Laboratory for Toxicology and Industrial Medicine, Newark, DE 19714.
authors.forename: G L
authors.initials: GL
authors.lastname: Kennedy
mesh_terms: D000280:Administration, Inhalation; D000284:Administration, Oral; D000818:Animals; D008297:Male; D009152:Mutagenicity Tests; D011743:Pyrimidines / Q000633:toxicity*; D051381:Rats
chemical_list: D011743:Pyrimidines; C078327:2-methyl-5,6-cyclopentapyrimidine