# Sulfur hexafluoride: MAK Value Documentation, addendum – Translation of the German version from 2023

## TL;DR

This paper updates the safe workplace exposure limit for sulfur hexafluoride based on new toxicological data and confirms its low reactivity under normal conditions.

## Contribution

The paper provides a re-evaluation of the MAK value for sulfur hexafluoride using recent toxicological studies and sets updated occupational exposure limits.

## Key findings

- Sulfur hexafluoride is inert under normal conditions and does not cause systemic or local effects in rats at high concentrations.
- Acute exposure to high concentrations of sulfur hexafluoride in humans causes sleepiness and analgesia.
- The MAK value for sulfur hexafluoride has been set to 5000 ml/m³ based on the NOAEC.

## Abstract

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area (MAK Commission) has re-evaluated the occupational exposure limit value (maximum concentration at the workplace, MAK value) of sulfur hexafluoride [2551-62-4] considering all toxicological end points. Relevant studies were identified from a literature search and also unpublished study reports were used. This addendum 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 hexafluoride 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.