1-Bromopropane has been newly introduced as an alternative to ozone layer-depleting solvents. We aimed to clarify the dose-dependent effects of 1-bromopropane on the nervous system. Forty-four Wistar male rats were randomly divided into 4 groups of 11 each. The groups were exposed to 200, 400, or 800 ppm of 1-bromopropane or only fresh air 8 h per day for 12 weeks. Grip strength of forelimbs and hind limbs, maximum motor nerve conduction velocity (MCV), and distal latency (DL) of the tail nerve were measured in 9 rats of each group every 4 weeks. The other 2 rats of each group were perfused at the end of the experiment for morphological examinations. The rats of the 800-ppm group showed poor kicking and were not able to stand still on the slope. After a 12-week exposure, forelimb grip strength decreased significantly at 800 ppm and hind limb grip strength decreased significantly at both 400 and 800 ppm or after a 12-week exposure. MCV and DL of the tail nerve deteriorated significantly at 800 ppm. Ovoid or bubble-like debris of myelin sheaths was prominent in the unraveled muscular branch of the posterior tibial nerve in the 800-ppm group. Swelling of preterminal axons in the gracile nucleus increased in a dose-dependent manner. Plasma creatine phosphokinase (CPK) decreased dose-dependently with significant changes at 400 and 800 ppm. 1-Bromopropane induced weakness in the muscle strength of rat limbs and deterioration of MCV and DL in a dose-dependent manner, with morphological changes in peripheral nerve and preterminal axon in the gracile nucleus. 1-Bromopropane may be seriously neurotoxic to humans and should thus be used carefully in the workplace.
In screening patch testing of hairdressers with occupational contact dermatitis, multiple positive reactions to hair dye-related chemicals, such as p-phenylenediamine (PPD), p-toluenediamine x 2HCl (PTD) and p-aminophenol (PAP), a fabric dye p-aminoazobenzene (PAB), and a tar dye Sudan III, were frequently encountered. To investigate individual skin sensitization potency and the cross-reactivities among above chemicals, a guinea pig maximization test with the above 5 chemicals was performed. In each group, 6 animals were induced with one of the chemicals at 0.1% concentration by intradermal injection and at 1.0% by topical application. The animals were challenged with all 5 chemicals in concentrations of dilution by 10 from 0.1% to 0.001%. Under the conditions of 0.1% challenges, similar sensitization potencies were observed in PPD (6/6), PTD (6/6), PAP (5/6) and PAB (6/6) groups, but no positive reactions were elicited in the Sudan III group. The cross-reactivities to PPD were confirmed in the animals challenged with PTD (6/6), PAP (6/6), PAB (6/6) and Sudan III (3/6). In the PTD-induced group, positive responses to cross-challenges were elicited by PPD (5/6), PAP (3/6), PAB (5/6) and Sudan III (1/6). The cross-reactivities to PAP were observed only with PPD (2/5) and PAB (5/5). PAB-induced animals responded only to PPD (1/6). The results indicate that all these chemicals except Sudan III are strong sensitizers. Their cross-reactivities are different in sensitized conditions, respectively. The cross-reactivities to PPD were higher than those to PTD, PAP and PAB.
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