A patient with peculiar pigmentation on the face and hands was examined and it was clarified that the nature of pigmentation was chronic melanodermatitis due to the rubber covering with which he was usually in contact to look into the radar in his working ferry boat.
The patient is a 40-year-old Japanese with no specific family history, working as captain of a ferry boat in the Setonaikai-line. He noticed reticular brownish black pigmentation with itchy dark reddish tone on periorbital regions, extending particularly to forehead, zygomatic regions, cheeks and nose, and the lateral margin and the back of hands about 6 months ago. These symptoms gradually increased. Histopathological examination of the left cheek with reticular pigmentation showed perivascular lymphoid infiltration and numerous melanophages in the upper dermis, and postinflammatory pigmentation was suggested. He used to look into the radar during the operation of his working ferry boat and the contact region of the rubber covering on the peephole of the radar-scope almost coincided with the peculiar pigmentation of the face. Patch tests with this rubber product and paraphenylenediamine, one of rubber antioxidants, showed positive results, but with mercaptobenzothiazole and tetramethylthiuram disulfide, accelerators producing most cases of rubber dermatitis, they were negative. As substances with similar structural formulas of paraphenylenediamine in rubber antioxidants may show cross-sensitized reactions, it was suggested that paraphenylenediamine or substituted paraphenylenediamine was contact allergens of this melanodermatitis. When the contact allergens, not so strong, continue to contact for a long time, liquefaction degeneration of basal cells occurs, then melanin granules, dropping to the dermis, are present as melanophages in the upper dermis. As such, the pigmentation seems to gradually appear. The literature reported hitherto in Japan on the chronic melanodermatitis due to rubber products is reviewed herewith.

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Personal air samplers were applied to workers dealing with trichloroethylene as washing solvent in an automobile workshop and exposure levels of the vapour were measured. At the same time, urinary metabolites (trichloroethanol, trichloroacetic acid, and total trichlorinated compounds) of the workers were measured at each excretion period. On the other hand, the levels of solvent vapours in the working yard were measured both by a room air sampler as time-weighted average concentrations and by Kitagawa detection tubes as spot-sampled concentrations at 30 minutes' intervals during the work time.
The time-weighted average concentrations of trichloroethylene vapour in the morning work time (3 hours) and in the whole working time (7 hours) measured by personal air samplers correlated well to the levels of trichloroethanol in the urine excreted 8 hours after the beginning of the work. This means that the measurement of the levels of trichloroethanol in the urine, collected at the end of the ordinary working time, is a reliable means to estimate the severity of personal exposure to trichloroethylene vapour. And the levels of the solvent vapour in the working yard measured as the time-weighted average concentrations were not always equal to those as the spot-sampled concentrations. The results suggested that it was necessary to measure both by the room air sampler (as the time-weighted average concentrations which are prescribed in the principles of the threshold limited values) and by the detection tubes (as monitors of ceiling values) for the environmental assessment of trichloroethylene vapour in the working yard.

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Personal air samplers were applied to shipyard's painters putting on gas masks during the spraying work, and the levels of toluene vapour surrounding the workers were measured. On the other hand, levels of urinary hippuric acid (metabolites of toluene) of the workers were measured, and the levels of toluene vapour inhaled were calculated from the levels of urinary hippuric acid. Then the actual removing-efficiencies of toluene vapours by the use of gas masks were estimated from these two levels (i.e., toluene vapours exposed and inhaled). The values of removing-efficiencies were found to be 65.9-98. 1%.
The concentrations of hippuric and methylhippuric acids in the urine of workers exposed to toluene and xylene for 3 hours, collected just after the exposure, are valuable indices of these organic solvent vapours inhaled.
A minute amount of urinary methylhippuric acid can be determined by means of gas chromatography.

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