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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Administrative data

Description of key information

Nitrous oxide is not very toxic after single or repeated exposures. Concentrations of 300 000 ml/m³ (545 455 mg/m3) and more have analgesic effects and concentrations of 800 000 ml/m³ (1 454 545 mg/m3) and more have anaesthetic effects (MAK value documentation, 1993).

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Endpoint conclusion:
no study available

Acute toxicity: via inhalation route

Link to relevant study records
Reference
Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
Swiss Webster mice (15/sex/gp) were exposed to N2O via whole body inhalation at concentrations of 0, 5000, 50000 or 500000 ppm [0, 0.5, 5, 50%] for 4/h/d, 5d/wk over 14 wks.
GLP compliance:
no
Limit test:
no
Species:
mouse
Strain:
Swiss Webster
Sex:
male/female
Route of administration:
inhalation: gas
Type of inhalation exposure:
whole body
Vehicle:
air
Duration of exposure:
4 h
Concentrations:
0, 5000, 50000 and 500000 ppm (0.5, 5, 50 %)
No. of animals per sex per dose:
27
Control animals:
yes
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 909 091 mg/m³ air
Based on:
test mat.
Exp. duration:
4 h
Key result
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 500 000 ppm
Based on:
test mat.
Exp. duration:
4 h
Mortality:
No animal died during the course of the study.
Interpretation of results:
GHS criteria not met
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
LC50
Value:
> 909 091 mg/m³ air
Physical form:
inhalation: gas
Quality of whole database:
Reliable with restrictions.

Acute toxicity: via dermal route

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Acute toxicity: via inhalation

No acute inhalation toxicity study following the OECD test guideline 403 is available. However, in the study of Rice et al. (1985) Swiss Webster mice (15/sex/gp) were exposed to nitrous oxide via whole body inhalation at concentrations of 0, 5000, 50000 or 500000 ppm [0, 0.5, 5, 50%] for 4h/d, 5d/wk over 14 wks. No morbidity or mortality was observed, with all animals surviving exposure day 14. The LC50 is estimated to be higher than 500000 ppm (=909091 mg/m3).

In the absence of specific data this study is deemed appropriate to address the assessment of acute inhalation toxicity of nitrous oxide.

Since nitrous oxide is a gas, the oral and dermal route is not relevant for the assessment of acute toxicity.

General remark

1 mL/m3 (ppm) = 1.83 mg/m3

Justification for classification or non-classification

Classification, Labeling, and Packaging Regulation (EC) No 1272/2008

While not following the test design of an acute inhalation toxicity study according to OECD TG 403, the study of Rice is considered sufficient to conclude that acute exposure to nitrous oxide is insufficient for classification for acute toxicity according to Regulation (EC) No 1272/2008, as amended for fifteenth time in Regulation (EU) No 2020/1182.

 

Due to its narcotic effects nitrous oxide is classified as STOT SE H336: May cause drowsiness or dizziness according to Regulation (EC) No 1272/2008, as amended for fifteenth time in Regulation (EU) No 2020/1182.