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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 re‐evaluated the maximum concentration at the workplace (MAK value) for isopropyl benzene [98‐82‐8]. Critical effects after repeated inhalation exposure to isopropyl benzene are the induction of tumours in the lung of mice and in the nose of rats as well as effects on the liver in these species. The classification of isopropyl benzene in Category 3 B for carcinogenic substances is retained. Based on the increased liver weight in a 14‐week inhalation study with rats, a MAK value of 10 ml/m3 has been set. This value is now reaffirmed even considering the increased respiratory volume at the workplace (see List of MAK and BAT values, chapters I b and I c). As there was a change in the Commissions evaluation on the adversity of increased liver weight, the new evaluation is based on the lower confidence limit of the benchmark dose (BMDL) of 42 ml/m3 for nasal adenoma in male rats in a two‐year inhalation study. As there is no new data, Peak Limitation Category II with excursion factor of 4 is retained and isopropyl benzene remains assigned to Pregnancy Risk Group C. Isopropyl benzene also remains designated with an “H” (for substances that can be absorbed through the skin in toxicologically relevant amounts).
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