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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) and the Pregnancy Risk Group of ethylbenzene [100‐41‐4]. Critical effect is the liver toxicity, which is observed as centrilobular hypertrophy and liver weight increase resulting from the induction of enzymes and proliferation of hepatocytes, in long‐term studies with rats and mice. In an oral 13‐week study a NOAEL of 75 mg/kg bodyweight and day for rats and a NOAEC of 75 ml/m3 for liver cell proliferation in mice were established. Based on this data, a MAK value of 20 ml/m3 had been set. This value is now reaffirmed even considering the increased respiratory volume at the workplace for the cell proliferation study (see List of MAK and BAT Values, Sections I b and I c). Since a systemic effect is critical, Peak Limitation Category II is retained and since it is not clear whether the effects are due to the metabolites or ethylbenzene the default factor of 2 is confirmed. The NOAEC for developmental toxicity in rats is 500 ml/m³ and after considering the increased respiratory volume at the workplace the difference to the MAK value is sufficient. Therefore, damage to the embryo or foetus is unlikely when the MAK value is observed and ethylbenzene remains in Pregnancy Risk Group C.
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