Sulphur hexafluoride

Neurotoxicity

Description of key information

The Functional Observational Battery (FOB) tests and spontaneous motor activity tests, performed as a part of a GLP-compliant 28-days repeated dose inhalation toxicity study with reproductive and developmental screening, revealed no effects in rats exposed to 302687 mg/m3 SF6 6h/day for at least 28 days. The substance is considered to be not neurotoxic.

Key value for chemical safety assessment

Effect on neurotoxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no study available

Effect on neurotoxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

NOAEC

302 687 mg/m³

Effect on neurotoxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

The neurotoxic potential of sulphur hexafluoride was evaluated in a 28-days repeated dose toxicity inhalation study with reproductive and developmental toxicity screening, performed under GLP and according to OECD Guideline 422 (TNO, 2009). Groups of 12 male and female Wistar rats were exposed to a limit (analytical) concentration of 302687 mg/m3 (target concentration of 50000 ppm) SF6 and air (control group) for 6

hours/day daily. Males were exposed for at least 2 weeks prior to mating, during mating and after the mating period at least until the minimum total exposure period of 28 days has been completed, while females were exposed for at least 2 weeks prior to mating, during mating and up to gestation day 19. Functional Observational Battery (FOB) tests, including an assessment of grip strength and sensory reactivity to stimuli of different types, and spontaneous motor activity measurements were performed in 5 males/group prior to the end of dosing and 5 females/group prior to day 4 of lactation. Males were sacrificed after 29 days of exposure; females at day 4 of lactation or shortly after.

No mortalities were noted. No adverse changes which were considered to be related to treatment were noted with respect to body weight, food consumption, gross pathology, clinical chemistry, haematological and histopathological examinations. Weekly detailed clinical observations outside the home cage did not indicate an effect. A statistically significant decrease of the landing footsplay and a statistically significant increase of the motor activity were observed in male animals of the SF₆-exposed group in comparison to controls. Those findings were considered incidental and are most probably due to the atypical (high) control values and did not reveal an effect when compared to the historical range. Furthermore, no other differences in neurobehavioural testing were observed between the control and the SF₆-exposed group.

Based on these results, the NOAEC for neurotoxic effects was set at 302687 mg/m³.

Justification for classification or non-classification

Based on the lack of neurotoxic effects in a GLP-compliant 28-days inhalation toxicity study with reproductive and developmental toxicity screening, classification is not warranted in accordance with EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation No. 1272/2008.