Graphite, acid-treated

Toxicity to soil microorganisms

Description of key information

Graphite, acid-treated is an inorganic solid, consisting of natural graphite and variable amounts of either intercalated nitric acid or acetic acid. The main component – graphite – is a naturally occurring inorganic solid substance which is insoluble in water. Due to its physico-chemical properties, i.e. absence of lipophilic functional groups which would enhance lipid (fat) solubilisation properties and therefore facilitate the uptake into the organism, graphite itself can be regarded as not bioaccumulative and harmless. Graphite cannot degrade and does not adsorb to organic matter in soil or sediment (see IUCLID points 5.2 and 5.4.1).
The nitrite and the nitrate are the corresponding reduction/oxidation counterparts in which they form intermediates in the course of the nitrogen cycle.  In the environment, bacteria of the genus Nitrobacter oxidise nitrites to nitrates. Nitrates are reduced to nitrogen by anaerobic bacteria present in soil and sediment (OECD SIDS Report for sodium nitrite; 2005). Acetic acid is a metabolisation and degradation product and occurs in various plants, such as juniper or tobacco. 
The low hazardous potential to microorganisms can be concluded from the negative testing results of a pre-incubation test (Ames Test) performed with several Salmonella typhimurium strains in order to investigate the potential of extracts of graphite, acid-treated to induce gene mutations. No cytotoxic effects of the test item extracts were noted in any of the five tester strains used (with and without metabolic activation) (see section 7.6.1 of the IUCLID dossier). Relevant exposure of soil to graphite, acid-treated is unlikely regarding its use pattern. 
Against this background testing of toxicity of graphite, acid-treated to soil microorganisms is not required under Regulation (EC) No 1907/2006 (REACH).