Metallic mercury induced tremor in rabbits and mercury content of the central nervous system

Fukuda, K. (1971).Brit. J. industr. Med.,28, 308-311. Metallic mercury induced tremor in rabbits and mercury content of the central nervous system. Tremor induced by metallic mercury was experimentally produced in rabbits by intermittent exposure to mercury vapour (average concentration of 4·0 mg/m³ for 6 hr/day on 4 days/week for 13 successive weeks). Two of six male rabbits exposed developed fine tremor and clonus in the fore- and hind-legs after 13 weeks' exposure. Electromyographic records showed typical grouped voltages accompanying the clonus (amplitude 0·3 to 1·0 mV, duration 20 to 30 ms, frequency 14 to 15 per second). Activation analysis of the central nervous system showed mercury levels ranging from 0·8 to 3·9 μg/g wet tissue. The concentration in the cerebellum, the tegmentum, and the thalamus was significantly higher than in the remaining structures. The relationship between the tremor and the mercury content of the central nervous system is discussed and a positive causal relationship is suggested.