Graphite

Endpoint summary

Description of key information

Acute toxicity: oral

- OECD 423, conducted as limit test

- None of the animals showed any clinical signs of reaction to the treatment.

- LD50 > 2000mg/kg bw

Acute toxicity: inhalation

- OECD 403, conducted as limit test

- Upon cessation of exposure via inhalation none of the rats exposed to Graphite showed any signs of toxicity.

- Only usual signs of discomfort after exposure to particles were observed. Grooming activity started immediately after the end of exposure.

- LC50 > 2000mg/m3

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

LC50

Value:

2 000 mg/m³ air

Additional information

Two qualities of Graphite were considered for the present registration dossier: Synthetic Graphite (SG) and Expanded Graphite (EG). Both are high purity graphite qualities with SG having the higher purity (>99%) and no amounts of quartz or any other crystalline impurities. EG however may contain certain (but low) amounts of quartz (typical quantity: 0.9%) and muscovite (typical quantity: 1.2%), hence making it the slightly more adverse test item for inhalation exposure, which was primarily investigated. Due to the absence of crystalline impurities and the fact that no other impurities of concern are contained in SG, results obtained for EG are valid for SG as well. For animal welfare and technical reasons, i.e. to prevent agglomeration of particles and to assure an MMAD in the respirable range from 1 -4µm, an aerosol concentration of 2000mg/m³ was used in this limit test as recommended by Regulation (EC) 1272/2008 and OECD403.

Based on the physico-chemical properties (i.e. water solubility and particle size) it is not expected that Graphite can be absorbed via the gastrointestinal tract after oral administration. In the study on acute toxicity via oral route of exposure (conducted as limit test as well) no sign of systemic toxicity was found. EG was used as test item for these studies, however, it is not expected that any of the impurities of SG (i.e. traces of iron) would show any effects (GESTIS-database on hazardous substances (2010 -08 -06) LD50 > 30000 mg/kg). Consequently, the results of the acute toxicity study via oral route of exposure using EG are applicable for SG as well.

Studies on dermal exposure were disregarded, since it is based on the physico-chemical properties (e.g. water solubility and particle size) not expected that Graphite particles can be absorbed through skin. Additionally, Graphite proved to be neither irritating nor corrosive to the skin or to the eyes in the newly performed studies.

 

Justification for classification or non-classification

Following the results of these newly conducted OECD studies, Expanded Graphite powder (and Synthetic Graphite powder) is neither acute toxic via inhalation nor via oral route of exposure, with LC50-/LD50-values above the respective limit concentrations. Dermal penetration is not likely. Therefore, according to the provisions laid down in Council Regulation (EC) No 1272/2008 Graphite powder does not meet the criteria for being classified as acute toxic, neither by oral route or via inhalation. Classification for acute toxicity via dermal route of exposure is not justified, since skin adsorption cannot be expected and all studies on irritation clearly showed no irritating effect to the skin. Hence no classification for acute dermal toxicity is proposed.