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In Annex X of the Regulation (EC) No 1907/2006 REACH concerning the Registration, Evaluation, Authorisation of Chemicals (REACH), it is suggested, that "in the absence of toxicity data for soil organisms, the equilibrium partitioning method may be applied to assess the hazard to soil organisms. The choice of the appropriate tests depends on the outcome of the chemical safety assessment. In particular for substances that have a high potential to adsorb to soil or that are very persistent, the registrant shall consider long-term toxicity testing instead of short-term.

Chloromethane is gaseous and the primary environmental compartment to which it partition is air. In accordance with REACH regulation, the studies need not to be conducted if exposure to soil and sediment is unlikely. Volatilization of chloromethane from moist soil surfaces is expected to be an important fate process. Considering its solubility, volatility and resultant Henry’s Law Constant, chloromethane is expected, under equilibrium conditions, to exist principally in the air. Mackay Level III simulations were used to evaluate the effect of source of entry on the distribution and persistence of chloromethane. As expected; the emission of chloromethane directly to air resulted in > 99% of the total chemical mass residing in the air compartment. Only insignificant amounts of chloromethane will be found in the soil or sediment compartments, regardless of source of entry to the environment. Since chloromethane is a gas, most industrial releases are expected to be directly to the air compartment. In a study from Brahusi et al. (2002) to investigate the behaviour of chloromethane in arable soil, the results showed clearly that volatilization is the main loss mechanism of chloromethane from soil (69.2-70.9% within 3 -4 days). This is in accordance with another study from Wang (1994), who reported also volatilization from soil as main loss pathway. Additionally, the substance is not expected to adsorb to soil based upon the log Koc.

The substance is readily biodegradable, has a low potential for adsorption and does not bioaccumulate. These characterists suggest a small hazardous potential towards soil organisms. Therefore, the equilibrium partitioning method has been used to assess the hazard potential of chloromethane for soil organisms.