A new study conducted by ECSA on biodegradation of dichloromethane in a closed bottle test according to OECD guidelines resulted in this finding. The study was required after an international agreement was reached this year by the OECD Cooperative Chemicals Assessment Programme on the hazard assessment of dichloromethane, leading to intense discussions on the available data on biodegradation for the substance.
The focus of the OECD Cooperative Chemicals Assessment Programme is to derive OECD-wide agreed hazard assessments of chemicals. These are available to the public and can be used for risk assessment and other activities within national or regional programmes.
The substance dichloromethane was assessed under this programme by the OECD Member States end of last year. The available studies demonstrate that methylene chloride is rapidly biodegradable. However, these studies were judged insufficient by OECD to allow classification as readily biodegradable due to the volatility of the substance and lack of a suitable OECD guideline test (OECD 301). A recently performed Closed Bottle test (OECD 301 D) with dichloromethane confirmed that this substance is rapidly and readily biodegradable.
The members of the European Chlorinated Solvent Association (ECSA) welcomed the test results which will lead to an update of both the REACH and the OECD assessment of methylene chloride.