The German Commission for the Investigation of Health Hazards of Chemical Com- pounds in the Work Area (MAK Commission) has re-evaluated the occupational expos- ure limit value (maximum concentration at the workplace, MAK value) of sulfur hexa- fluoride 2551-62-4 considering all toxicological end points. Relevant studies were iden- tified from a literature search and also unpublished study reports were used. This adden- dum evaluates only pure sulfur hexafluoride. Reaction products that are highly toxic for humans can form during its use as an insulating gas in high voltage switchgear. Under normal conditions, the reactivity of sulfur hexafluoride gas is comparable to that of helium or nitrogen. Therefore, systemic or local effects were not observed in studies carried out in compliance with OECD test guidelines with exposure of rats to the gas at concentrations up to 20 052 ml/m3 for 13 weeks. Acute exposure to 550 000 ml/m3 (55%) induced sleepiness and analgesia in humans. On the basis of the NOAEC of 20 052 ml/m3 , a maximum concentration at the workplace (MAK value) of 5000 ml/m3 has been set. As significant effects were not observed in humans up to 390 000 ml/m3, Peak Limitation Category II and the excursion factor of 8 have been retained. Sulfur hexafluoride showed no genotoxic potential. Carcinogenicity studies have not been carried out. Sulfur hexa- fluoride was not teratogenic in a developmental toxicity study in concentrations up to 19 100 ml/m3, but led to a transient delay in foetal development. After consideration of all data as well as the fact that sulfur hexafluoride is inert under normal conditions, it has been assigned to Pregnancy Risk Group C. There are no data for the sensitizing potential of sulfur hexafluoride. Skin contact is not expected to contribute significantly to systemic toxicity.
Hartwig et al. (Mon,) studied this question.