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1000
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Abstract/Summary
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The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has derived a biological guidance value at the workplace (“Biologischer Leitwert”, BLW) and a biological reference value (“Biologischer Arbeitsstoff‐Referenzwert”, BAR) and has re‐evaluated the exposure equivalents for carcinogenic substances (EKA) for cobalt and cobalt compounds [CAS No. 7440‐48‐4] in 2017. Available publications are described in detail. The evaluation of the BLW was based on the association between urinary concentration of cobalt to characterize the internal exposure and cardiotoxicity as critical effect. Moderate restrictive lung dysfunctions and slight interferences with thyroid metabolism (hypothyroidism) were observed at urinary cobalt concentrations of 79 µg/l urine and 84 µg/l urine, respectively. At urinary concentrations of 38 µg cobalt/l urine and 36 µg cobalt/l urine no adverse effects of restrictive lung dysfunction and cardiotoxicity were observed. Therefore, a BLW of 35 µg/l urine was derived. The sampling time is for long‐term exposures at the end of the shift after several shifts. In some biomonitoring studies, the excretion of cobalt in urine of persons occupationally not exposed to cobalt was examined. Due to geogenic differences, a German study was considered for the evaluation, where urine samples of 87 adults were analyzed and a 95th percentile of 1.53 µg cobalt/l urine was recorded. These results are in good accordance with other international studies. Therefore, a BAR of 1.5 µg cobalt/l urine was evaluated. The relationships between the concentration of cobalt in ambient air and that in urine derived from the more recent studies are in good accordance with the present EKA. The Commission therefore retains the EKA already derived in 1986 and extended in 2006 in the lower range between the concentration of cobalt in the air and in urine.
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