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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 tetrachloroethylene [127‐18‐4] to derive a maximum concentration at the workplace (MAK value), considering all toxicity endpoints. Available study reports and publications are described in detail. Results from human studies do not point to a genotoxic potential of tetrachloroethylene. In vitro and in vivo studies in mammalian cells do not show a distinct genotoxic potential. From epidemiologic and animal studies there is concern that tetrachloroethylene could be carcinogenic for humans; therefore, tetrachloroethylene has been classified in Carcinogen Category 3B. However, since carcinogenic effects are judged to be not predominantly caused by genotoxic mechanisms, a MAK value can be derived. Neurotoxicity is considered the most sensitive endpoint for tetrachloroethylene. In volunteers, repeated daily 4‐hour inhalation exposure caused small but significant effects on visual evoked potentials. The NOAEC was 10 ml/m3, but as only weak effects were observed at the LOAEC of 50 ml/m3, 20 ml/m3 is regarded as the NAEC. As a doubling of uptake is expected under workplace conditions, a MAK value of 10 ml/m3 has been set. As the critical effect is systemic, tetrachloroethylene is assigned to Peak Limitation Category II. The default excursion factor of 2 is set as the half‐life in the central nervous system is unknown. There is limited evidence suggesting that women working in a dry‐cleaner have an increased risk of spontaneous abortion. But the limited validity of the studies is not sufficient to prove a causal relationship. In developmental toxicity studies, NOAECs for developmental toxicity of 65 and 217 ml/m3 in rats, 500 ml/m3 in rabbits, and a LOAEC of 217 ml/m3 in mice were obtained. The NOAEC for behavioural toxicity in the offspring of treated rats was 100 ml/m3. The differences between these NOAECs as well as the LOAEC and the MAK value are considered so large that damage to the embryo or foetus is unlikely when the MAK value is observed. Therefore, tetrachloroethylene is classified in Pregnancy Risk Group C. Sensitization is not expected due to results of animal studies and experience in humans. Skin contact is expected to contribute significantly to the systemic toxicity of tetrachloroethylene. Therefore, designation with an “H” is confirmed.
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