Registration Dossier

Administrative data

Endpoint:
acute toxicity: inhalation
Data waiving:
study technically not feasible
Justification for data waiving:
other:

Data source

Reference
Reference Type:
other company data
Title:
Unnamed
Year:
2013

Materials and methods

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name: Carbamic acid, N-(3-(triethoxysilyl)propyl)2-(ethyl-(4-nitrosophenyl) amino) ethyl ester
- CAS 1195231-94-7

Results and discussion

Applicant's summary and conclusion

Interpretation of results:
not classified
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
In conclusion, an acute inhalation toxicity study according to OECD 403 is not performed due to the physico-chemical properties of the substance. Based on expert judgement and experience from oral application, nitrososilane is not considered to be hazardous by shortterm inhalation.
Executive summary:

Acute oral toxicity

The test item nitrososilane was investigated for its potential acute oral toxicity in rats following the protocol of OECD method 423 (Henkel, 2013a). All animals survived a dose of 2000 mg/kg until the end of the study. The median lethal dose (LD50) was found to be above 2000 mg/kg bw, which does not require classification under the EU regulation (Regulation (EC) 1272/2008). The substance has to be classified in category 5 for acute toxicity under the Globally Harmonized System of Classification and Labelling of Chemical Substances of the United Nations (UN-GHS).

Acute inhalation toxicity - waiving

lf the following conditions are met, a substance is exempted from testing for acute inhalation toxicity according to the Chinese Ministry of Environmental Protection Order No. 7, 2010:

- When the substance is kept at 20°C, the vapour pressure will be < 10-2 Pa; and

- < 1 % by weight of the particle size distribution of the substance can be inhaled. Moreover, the Mass Median Aerodynamic Diameter (MMAD) of generated aerosols, small particles or drops shall be > 100 μm.

The nitrososilane has been investigated regarding its physico-chemical properties. lt is a green solid powder which is subject to hydrolysis upon contact with moisture. lt is hygroscopic and not dusty.

The analytically determined vapour pressure of nitrososilane was not in the recommended range for measurements. By extrapolation, it was found to be far below 10-2 Pa. Because of this very low volatility, it is technically not feasible to produce a test atmosphere sufficient for testing vapours of nitrososilane in an acute inhalation toxicity study.

The particle size distribution of the powder was determined by sieving analysis (Henkel, 2013c) with the following results:

Particle size distribution with different particle classes

Grain fraction Percent by weight Frequency density Cumulative (%)
µm (g) Mass: 103.94 g (%) q3 (%/µm) Q3 (D) 1 -Q3 (R)
< 63 1.58 1.5 0.024 1.5 98.5
63 - 125 3.58 3.5 0.056 5.0 95.0
125 - 500 3.32 3.2 0.026 8.2 91.8
250 - 500 4.94 4.8 0.019 12.9 87.1
500 - 1000 7.89 7.6 0.015 20.5 79.5
1000 - 1400 6.65 6.4 0.016 27.0 73.0
> 1400 75.75 73.0 0.016 100.0 0.0

X10: 346 µm

X50: 2851 µm Mass Median Aerodynamic Diameter (MMAD)

X90: 5370 µm

In the gain fraction > 1400 μm are particle up to a size of 3.0 x 2.5 cm.

From this distribution it becomes clear that the particle size is very large (MMAD 2851 μm). A small fraction of 1.5% by weight has a size below 63 μm, which could at most reach the upper airways after inhalation. Particles of a size of 10 μm would be considered as inhalable, while even smaller particles of 4 μm would be respirable and could reach deeper areas of the lung. The fraction smaller than 10 μm was not determined but can be regarded as negligible from the given particle size distribution. Due to the large average particle size and hygroscopic properties of the substance, it is technically not feasible to create a test atmosphere of nitrososilane dust which is suitable for acute inhalation toxicity testing and

which reflects a realistic relevant exposure scenario.

Based on the described physico-chemical properties of this substance, the inhalative route is not a likely portal of entry for nitrososilane. Due to the physico-chemical properties of nitrososilane, the necessary atomization or aerosolization of this chemical will be significantly limited if not impossible. Therefore, from a technical perspective, the physico-chemical characteristics prevent administration of precise and consistent doses of this substance in an acute inhalation test.

Moreover, based on the result of the acute oral toxicity study, with the assumption of a higher body burden compared to any such by inhalation exposure, any relevant acute inhalation toxicity potential seems to be unlikely.

Conclusion

In conclusion, an acute inhalation toxicity study according to OECD 403 is not performed due to the physico-chemical properties of the substance. Based on expert judgement and experience from oral application, nitrososilane is not considered to be hazardous by shortterm inhalation.