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Description of key information

Acute toxicity for OTNE:

- Oral (OECD TG 401): LD50 >5000 mg/kg bw

- Dermal (OECD TG 402): LD50 >5000 mg/kg bw

- Inhalation (route to route extrapolation from acute oral information): LD50 > 22360 mg/m3

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Quality of whole database:
The acute oral toxicity result is of sufficient quality and adequate for this dossier.

Acute toxicity: via inhalation route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Quality of whole database:
The derived acute inhalation toxicity result is of sufficient quality and sufficiently adequate for this dossier.

Acute toxicity: via dermal route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Quality of whole database:
The acute dermal toxicity result is of sufficient quality and adequate for this dossier.

Additional information

Acute oral toxicity


The acute oral toxicity of the test substance was examined in a limit test. In a preliminary assay in which two rats were treated by gavage at 5000 mg/kg bw, there were no deaths during the 72 hour observation period. Ten male and ten female albino rats (TacN(SD)fBR) weighing between 180 and 280 grams were fasted overnight and were then dosed by gavage with 5000 mg/kg bw of the test article. None of the animals showed any pharmacological effect or clinical sign indicative of toxicity. All of the animals appeared normal in health and behaviour throughout the study. There were no deaths. At necropsy, none of the animals had any signs indicative of systemic toxicity. The LD50 was in excess of 5000 mg/kg under the conditions of the current study and the compound was therefore assessed as practically non-toxic. Based on EU criteria the substance does not have to be classified as acute toxic (oral).


Acute inhalation toxicity


The acute inhalation toxicity for the substance can be derived using data on the acute oral toxicity using the following methodology: CLP guidance (2017, 3.1.5.1.8. Example 8, page 264):using the extrapolation formula 1 mg/kg bw = 0.0052 mg/l/4h. 


The LD50 of the substance for acute oral toxicity is > 5000 mg/kg bw. This 5000 mg/kg bw can be converted to > 26 mg/l = 26 gram/m3. Taking into account the inhalation absorption as 100% and oral absorption 86%, the acute inhalation toxicity would become =>22360 mg/kg bw.


The saturated vapour pressure of the substance is: 48.5 mg/m3 (MW*VapPres/ (8.3*293). This means that the acute inhalation LC50 > 22360 mg/m3 cannot be reached because it exceeds the saturated vapour pressure by more than a factor of 400 (461).


Acute dermal toxicity


The dermal acute toxicity of the test substance, a yellow liquid, was examined (similar to OECD test guideline 402, 1987). In a preliminary assay in which two rats of each sex were dosed by application of a prepared alcoholic solution of the test substance to the skin at 5000 mg/kg bw, there were no deaths during the 72 hour observation period. Eight male and eight female albino rats (Sprague-Dawley CD strain), weighing between 180 and 280 grams, were clipped on the day prior to dosing and the test substance, prepared in the diluent supplied, was applied onto the skin at 5000 mg/kg bw. The volume of the solution administered was 0.5 ml/100 g bw.


None of the test animals showed any clinical signs indicative of systemic toxicity. All of the animals remained healthy throughout the study and gained weight in a normal manner. At necropsy performed on the survivors at term, none of the animals had any signs indicative of systemic toxicity. The dermal LD50 was greater than 5000 mg/kg bw.

Justification for classification or non-classification

Based on the available information in the dossier, the substance OTNE does not need to be classified for acute toxicity via the oral, dermal, and inhalation route when considering the criteria outlined in the EU CLP (EC 1272/2008 and its amendments).