Graphite, acid-treated

Biodegradation in soil

Description of key information

The main component – graphite - is a naturally occurring inorganic solid substance which is insoluble in water. Due to its physico-chemical properties it is neither not systemically and biologically available and does not cross biological membranes. In the aquatic compartment it can be considered as an inert substance. Biologically mediated degradation or transformation of graphite carried out by microorganisms can therefore be excluded. 
The intercalated acid – either nitric acid or acetic acid – and the intercalated ions (nitrate/nitrite or acetate) are partially leached out by water. All ions dissociate into the environmentally ubiquitous nitrite/nitrate/acetate and hydronium ions. 
Nitric acid will be gradually neutralized by hardness minerals (calcium and magnesium) in water. The nitrate ion may persist longer but will ultimately be consumed as a plant nutrient. In the aquatic/sediment compartment the nitrate ion is subject to a denitrification process for which anaerobic conditions are essential. 
Nitrite ions are ubiquitous in the environment and are part of the nitrogen cycle. In the course of the nitrification process Bacteria of the genus Nitrobacter oxidise nitrites to nitrates which in a subsequent step are reduced under anaerobic conditions to nitrogen.  
Acetic acid occurs ubiquitously and is a normal metabolite in both plants and animals. The acetic ion is subject to degradation under aerobic as well as anaerobic conditions. 
Production, handling and use of the substance only take place at a small number of industrial sites with no probability of any significant release from products during its life cycle.  Given the inherent properties of graphite, acid-treated and the unlikelihood of exposure of soil to this substance, testing of biodegradation is considered not to be necessary and is not required under Regulation (EC) No 1907/2006 (REACH).