Registration Dossier

Administrative data

Description of key information

There are no data on oral and dermal repeat dose toxicity. Studies are not technically feasible as the substance is a gas at room temperature. The limited data available on a close related substance indicates low toxicity via the inhalation route. It is concluded that there are no adverse effects resulting from repeat dose exposure below the lower explosive limit (LEL) of acetylene (2.5%; 26750 mg/m3).

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Oral and dermal

There are no data on oral and dermal repeat dose toxicity. Studies are not technically feasible as the substance is a gas at room temperature

Inhalation

In consideration of repeat dose toxicity, it is of note that acetylene is metabolised only to a very small extent (~1% if inhaled volume). A highly reactive ketene intermediate may be formed but very rapidly deactivated to acetic acid and it was estimated that no more than 1% of the inhaled amount of acetylene in humans is metabolised to acetate, a natural product (see section 5.1.1 above for further detail). Some repeat-dose studies at anaesthetic concentrations have been reported for acetylene. Excluding the acute effects associated with exposure to acetylene with its well-known anaesthetic and/or asphyxiant properties, there is no evidence of repeat dose toxicity, even at rather high concentrations leading to the conclusion that there are no repeat dose toxicity effects up to the lower explosive limit (LEL) of acetylene.

Justification for classification or non-classification

Due to lack of exposure via the oral or dermal routes (the substance is a gas at room temperature) and very low toxicity following inhalation exposure of a related substance, acetylene does not warrant classification under CLP.