Boron carbide

Endpoint summary

Description of key information

There are no studies available for the skin irritation and corrosion endpoint as such. However, data from an acute dermal toxicity study do not indicate any signs of skin irritation after topical application of the test item.

In addition, there were no studies available for the eye irritation endpoint.

Due to the inherent physical-chemical properties of B4C (sand-like, granulated, solid particles insoluble in water, showing no acidity) and long-term experience in manufacture, handling and use of boron carbide, no relevant toxicological risk is to be expected from boron carbide, when applied to the skin or into the conjunctival sac of the eyes. Due to the physico-chemical properties it is more likely, that boron carbide would predominantly cause mechanical damage to the eye.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vitro / ex vivo

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because an acute toxicity study by the dermal route does not indicate skin irritation up to the relevant limit dose level (2 000 mg/kg body weight)

Interpretation of results:

not irritating

Remarks:

Migrated information

Endpoint conclusion

Endpoint conclusion:

no study available

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vitro / ex vivo

Data waiving:

study technically not feasible

Justification for data waiving:

other:

Endpoint conclusion

Endpoint conclusion:

no study available

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Boron Carbide („Black Diamond“), a covalent non-metallic carbide, is an inorganic solid (sand-like, granulated, solid particles) with a high chemical inertness. With a hardness of 9.3 on the mohs scale, it is one of the hardest materials known, behind cubic boron nitride and diamond. It does not noticeably react with chlorine or oxygen below 1,000 °C, is completely inert against hydrogen fluoride and hot nitric acid and is practically insoluble in water (see section 4.8 of the IUCLID dossier) and organic solvents [1]. The acidity of B4C was determined according to CIPAC MT 191. No significant acidity of B4C has been detected. The mean acidity, calculated as H2SO4, was determined to be 0.01 %, m/m (see section 4.20 of the IUCLID dossier).

According to Column 2 of REACH Annex VIII (standard information requirements for substances manufactured or imported in quantities of 100 tonnes per year or more) of Regulation (EC) No 1907/2006, studies on skin irritation/corrosion do not need to be conducted if an acute study by the dermal route does not indicate skin irritation up to the limit dose level of 2,000 mg/kg body weight. According to the results of the “Acute Dermal Toxicity Limit Test with Boron Carbide B4C”, performed according to OECD Guidelines for Testing of Chemicals (Section 4, No. 402, "Acute Dermal Toxicity"), single dermal application of boron carbide to rats at a dose of 2,000 mg/kg body weight was not associated with significant signs of skin irritation (see section 7.2.3 of the IUCLID dossier). 

 

Furthermore, companies involved in the elaboration of the registration dossier confirmed by certificates of their company doctors that in up to 23 years of manufacturing, handling and use of B4C no cases of skin irritation or skin corrosion and no cases of eye irritation or eye corrosion occurred due to exposure of workers to B4C. For details see attached company declarations on observations of skin and eye irritation/corrosion and sensitising effects related to handling and use of boron carbide. Due to the inherent physical-chemical properties of B4C (solid particles, practically insoluble in water, showing no acidity) and long-term experience in manufacture, handling and use of boron carbide no relevant toxicological risk is to be expected from boron carbide, when applied to the skin or into the conjunctival sac of the eyes. Due to the physico-chemical properties it is more likely, that boron carbide would predominantly cause mechanical damage to the eye.B2O3 is the only Boron containing impurity of B4C soluble in water (see section 4.8 of the IUCLID dossier). B2O3 forms boric acid when being solubilised in water. However, boric acid itself is not classified as corrosive to the eyes or the skin.

Taking into account the outcome of the acute study by the dermal route (absence of skin irritation up to the limit dose level of 2,000 mg/kg body weight) performance of a study to determine the skin irritation potential of boron carbide is not required under Regulation (EC) No 1907/2006 (REACH).  

Based on the weight-of-the-evidence-analysis, it is not considered reasonable to perform an Eye Irritation study with B4C particles with regard to the physical properties of the test item and due to animal welfare reasons (see attached expert statement of BSL Bioservice). Against this background, in accordance with ECHAs principle of avoidance of unnecessary animal testing, performance of a study on eye irritation is considered not to be necessary.

[1] Hollemann A.F., Wiberg E., Lehrbuch der anorganischen Chemie, 101. Auflage, Walter de Gruyter, New York 1995. 

Justification for classification or non-classification

Based on relevant information from an acute dermal toxicity limit test and data describing the inherent physical-chemical properties of Boron Carbide (sand-like, granulated, solid particles insoluble in water, showing no acidity) and long-term experience in manufacture, handling and use of the substance, it is not considered likely that boron carbide will cause irritative/corrosive effects to the skin and eyes.

Therefore, classification according to the criteria set out in Annex I of Regulation (EC) No. 1272/2008 (CLP criteria) is not warranted.