Abstract:We encountered three patients (Patient I: 39-year-old man, Patient II: 34-year-old woman, and Patient III: 5-year-old girl) with acute methyl bromide poisoning, which had occurred as a result of exposure to the gas that leaked from methyl bromide cans stored in a warehouse of a seedling farm. Since all three patients exhibited almost the same initial symptoms, i.e., severe vomiting, tonic convulsions and clouding of consciousness, botulism was suspected at first. However, subsequent inquiry revealed that 27 cans of methyl bromide had been stored in the building that the patients lived in, and that the cans had been damaged a few days before the onset of the patients' illness by a thrashing machine that was being moved by them to another location. Inspection revealed that all the cans of methyl bromide had passed the expiry date and were corroded. Even though none of the cans had been used, three cans with a capacity of 750 g were found to be empty. Plasma bromide ion concentrations were determined to be high (72.9 µg/ml, 67.8 µg/ml and 91.5 µg/ml; normal level, <5 µg/ml), and acute methyl bromide poisoning was diagnosed 8 days after admission of the patients to the hospital. Hemodialysis (peritoneal lavage in the case of the child) was performed immediately, after which the plasma bromide ion concentrations returned to normal and the general condition of the patients gradually improved.

To elucidate the circumstances of their occupational exposure to methyl bromide (MeBr), we conducted a 17-yr study on 124 workers employed by a MeBr manufacturer. Subjects were classified into three groups according to the nature of their work: synthesis group, filling group, and other group. Urinary concentrations of bromide ion (Br -) were assessed, and data attained via MeBr-health examinations were analyzed. The highest Br -concentrations were seen in the synthesis group, with a median value of 13.0 μg/mg CRE (2.5-51.8), followed by the filling group, with a concentration of 11.9 μg/mg CRE (3.1-34.8). Both values were significantly higher than the levels noted in the other group (p<0.001). Three major opportunities for exposure were identified: during exchange of reaction equipment for maintenance or cleaning, during operations to adjust for weight variations after filling canisters, or when canisters were recycled. Overall, however, the workplace environment concentration remained largely below the administrative control level throughout the study period. Therefore, while this was a relatively well-controlled workplace, exposure opportunities still arose when performing certain tasks, indicating the need for ongoing improvement in workplace procedures and underscoring the importance of biological monitoring.

This report studies 100 cases of occupational bladder cancer which were reported between 1949 and 1970 by large companies producing dye. It is estimated that in fact a great many more than 100 cases may have developed during the 56 years from 1914 to 1970, as this period corresponds with the beginning of dye production to the termination of benzidine and beta-naphthylamine manufacture in Japan. New cases of occupational bladder tumour should diminish significantly in the future in Japan on account of the prohibition of the production of beta-naphthylamine and benzidine. However, it is important to follow-up continuously workers who have been exposed to these amines. In Japan no cases of occupational bladder tumours from the rubber industry have been reported. It is emphasized that prospective epidemiological studies are required not only in the rubber industry but also in other industries where amines may constitute an occupational hazard.

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