Cobalt concentration in urine as an indicator of occupational exposure to low level cobalt oxide.

The aim of this study was to verify the relationship between the cobalt oxide concentration in air and the cobalt concentration in urine. In the first study, we measured the cobalt concentration in the urine of 16 workers exposed to cobalt oxide in a Digital Video Cassette manufacturing plant at the beginning and end of their workshift during 2 working cycles. In the second study, we measured the exposure level to cobalt oxide and the cobalt concentration in urine at the end of the workshift of other 16 workers on 3 out of 5 consecutive work days (Monday, Wednesday and Friday). Four workers among the 16 participated twice. In the first study, the cobalt concentration in the urine increased about 1.5-3 fold during each workshift and then tended to decrease rapidly to the control value before the next workshift. In the second study, we examined the relationship between air and urine concentration using 22 samples after excluding data from workers with dust respirators. Comparing the air and urine concentrations for samples under 30 microg/m3 (n = 20), a significant correlation was found (r = 0.76). These results indicate that most of the inhaled cobalt oxide was excreted rapidly, and a good relationship was found between air and urine concentrations at the end of the workshift when the exposure level was under 30 microg/m3. Therefore, the cobalt concentration in urine at the end of a workshift can be used as an indicator of one-day exposure to cobalt oxide when the exposure is low level.

Occupational dermatitis from soldering flux.

The aim of this study was to determine the specific agent responsible for eczema on the forearms of 2 electronic assemblers who cleaned out a flux-spraying unit once a week. Soldering flux can be a source of skin irritation as well as allergy. Patch test with dried flux residue (as is) and rosin in dilution series of 20%, 10%, and 1% in olive oil was performed. Readings were taken on day 2 and day 3. The rosin in dilution series was negative; however, the flux residue gave a + reaction on day 2, and by day 3 the reaction had weakened (+?). Similar results were obtained in 2 unexposed controls. Patch tests results in our cases indicate that the flux used in the soldering process caused irritant contact dermatitis.

[Investigation of the cause of contact dermatitis due to heavy metal in a metal spray process in a film-condenser factory].

To investigate causes of contact dermatitis in the metal spray process in a film-condenser factory, we developed a questionnaire survey for workers exposed to metal dust, analyzed the metal dust, and conducted patch tests with the metal dust and its constituents. In the questionnaire survey, we identified 12 workers (12/26, 46.2%) who had had dermatitis. The main symptoms were itching, itchy red skin and itchy papules. Analysis of the metal dust showed that there was no copper oxide, but nickel, not contained in the materials of the metal spray, was detected. One worker with dermatitis had a positive reaction to 2.5% nickel sulphate. Some of the workers showed primary irritant reactions to 5% copper sulphate. As a result, we considered that these cases of dermatitis involved irritant contact dermatitis due to copper and/or allergic contact dermatitis due to nickel. To prevent dermatitis, we recommended improvement in ventilation, reducing the room temperature to reduce sweating, and to educate workers on the importance of frequent hand washing. Thereafter, the incidence of dermatitis decreased, and there were no cases requiring medication.