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Administrative data

Description of key information

LD50 for oral dose in rats is >2000 mg/mL
LD50 for inhalation does in rates is >5.07 mg/L
Requirement for dermal toxicity study is waived

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Quality of whole database:
Two recent studies performed to methods consistent with modern guidelines are available; the results of these studies compliment one another and indicate no toxic effect of silicon nitride by oral administration.

Acute toxicity: via inhalation route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed

Acute toxicity: via dermal route

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Oral Route

The key study for acute oral toxicity in rats was performed with Silicon Nitride by oral gavage (ARC Seibersdorf research GmbH, 2005) according to GLP and internationally accepted guidelines. Both male and female rats were dosed with 300 mg/kg/bw to start with. Further doses were administered, according to the accepted guidelines, at 2000 mg/kg bw. No adverse signs in either male or female rats were observed. Therefore the LD50 was estimated to be >2000 mg/kg/bw in rats. A supporting study is available for acute oral toxicity performed with Silicon Nitride by oral gavage in rats according to GLP and internationally accepted guidelines (Nihon Bioresearch, 2002). In this study, the LD50 was also estimated to be >2000 mg/kg/bw.

Inhalation Route

The key study for acute inhalation toxicity was performed with Silicon Nitride (ARC Seibersdorf Research GmbH) according to GLP and internationally accepted guidelines. A limit test was performed, with a test substance concentration of 5.07 mg/L. There were no adverse signs of toxicity in either male or female rats. The inhalation LC50 was therefore >5.07 mg/L.

Dermal Route

Since oral and inhalation acute toxicity studies are available, a dermal toxicity study is not necessary.


Justification for selection of acute toxicity – oral endpoint
The selected study was conducted according to identified international test guidelines and the study report included a claim of GLP compliance. A second study is available which was considered reliable as the methodology was well documented and was compatible with modern test guidelines, however the report did not include a formal claim of GLP compliance, and so the ARC study was considered the more reliable of the two.

Justification for selection of acute toxicity – inhalation endpoint
Study carried out to internationally accepted guidelines and according to GLP.

Justification for selection of acute toxicity – dermal endpoint
Acute toxicity testing by both oral and inhalation routes are available. Therefore an acute dermal toxicity test is not required.

Justification for classification or non-classification

Silicon Nitride is not classified on the basis of acute oral and inhalation toxicity.

The oral LD50 is >2000 mg/kg/bw, therefore Silicon Nitride does not meet the criteria for classification for acute oral toxicity according to the CLP Regulation or the Dangerous Substances Directive.

The inhalation LC50 is >5.07 mg/mL and therfore Silicon Nitride does not meet the criteria for classification for acute toxicity by inhalation under either the CLP Regulation or the DSD.

In each of the acute studies by the oral or inhaled route, no indication of Specific Target Organ Toxicity was observed and there is therefore no basis by which a classification for STOT (Single exposure) might be applied.