COMPARATIVE ACUTE TOXICITY AND PRIMARY IRRITANCY OF THE ETHYLIDENE AND VINYL ISOMERS OF NORBORNENE

The acute toxicity and primary irritancy of the industrial chemicals 5 -ethylidene-2-norbomene (ENB) and 5-vinyl-2-norbornene (VNB) were stud ied, They are of moderate acute peroral toxicity in the rat, with LD50 values for ENB of 2.54 (male) and 5.66 (female)ml kg(-1), and for VNB of 5.90 (male) and 11.9 (female) mi kg(-1). Percutaneous toxicity is slight in the rabbit by 24-h occluded contact, with no mortalities for ENB up to 8.0 ml kg(-1) and only one mortality (male) at 16.0 ml kg(- 1) VNB, Dynamically generated saturated vapor atmosphere LT50 values f or ENB in the rat were 75 (male) and 125 (female) min, and for VNB the y were 28 (male) and 37 (female) min, The 4-h LC50 values for ENB were 2717 (male) and 3015 (female) ppm, and for VNB they were 2231 (male) and 2518 (female) ppm, Intravenously, the ENB Lo(50) ranged from 0.09 (male rabbit) to 0.11 ml kg(-1) (female); corresponding Lo(50) values for VNB were 0.10-0.05 mg kg(-1). Acute neurotoxic signs were seen by the intravenous and inhalation routes of exposure, including tremors, ataxia and convulsions; the latter were sufficient to cause vertebral column luxation or fracture, producing spinal cord compression and res ultant hindlimb paralysis, Both ENB and VNR are moderately irritating to the skin (rabbit), causing erythema and edema, but not necrosis, Bo th materials cause slight conjunctival hyperemia and chemosis in rabbi ts, but not corneal injury. (C) 1997 John Wiley & Sons, Ltd.