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The biodegradation of musk xylene in sea water and in mixed sea water/sediment systems was studied in laboratory simulations using [[carbon-14]] labelled musk xylene, and the results discussed in an addendum to the ''European Union Risk Assessment Report''.<ref name="ECHA08" /> The half-life in [[marine sediment]] was estimated to be 60 days or less, with biodegradation occurring by anaerobic reduction of the nitro groups. The half-life in sediment-free sea water was estimated to be more than 150 days, far above the "very persistent" threshold of 60 days.<ref name="REACHx13" /> The 2008 addendum also discussed the photolysis of musk xylene in water and in air, which are rapid: however, photolysis was not considered to be relevant in the persistence of musk xylene in the environment, and was not taken into account in classifying it as a "very persistent" substance.<ref name="ECHA08" /> |
The biodegradation of musk xylene in sea water and in mixed sea water/sediment systems was studied in laboratory simulations using [[carbon-14]] labelled musk xylene, and the results discussed in an addendum to the ''European Union Risk Assessment Report''.<ref name="ECHA08" /> The half-life in [[marine sediment]] was estimated to be 60 days or less, with biodegradation occurring by anaerobic reduction of the nitro groups. The half-life in sediment-free sea water was estimated to be more than 150 days, far above the "very persistent" threshold of 60 days.<ref name="REACHx13" /> The 2008 addendum also discussed the photolysis of musk xylene in water and in air, which are rapid: however, photolysis was not considered to be relevant in the persistence of musk xylene in the environment, and was not taken into account in classifying it as a "very persistent" substance.<ref name="ECHA08" /> |
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Several different primary bioaccumulation studies were reviewed in the ''European Union Risk Assessment Report'', with bioaccumulation factors varying between 640 L/kg and 6740 L/kg.<ref>Section 3.1.1.2, ''European Union Risk Assessment Report'' (2005), pp. 12–15.</ref> Given that musk xylene has a very high [[octanol–water partition coefficient]] (log ''K''<sub>ow</sub> = 4.9),<ref name="PhysProps" /> the higher bioaccumulation factors were considered to be the more significant. The 2008 addendum<ref name="ECHA08" /> considered a further laboratory study from the Japanese [[Ministry of International Trade and Industry]] which was not available to the authors of the original Risk Assessment Report and which also showed bioaccumulation factors in fish (''[[Cyprinus |
Several different primary bioaccumulation studies were reviewed in the ''European Union Risk Assessment Report'', with bioaccumulation factors varying between 640 L/kg and 6740 L/kg.<ref>Section 3.1.1.2, ''European Union Risk Assessment Report'' (2005), pp. 12–15.</ref> Given that musk xylene has a very high [[octanol–water partition coefficient]] (log ''K''<sub>ow</sub> = 4.9),<ref name="PhysProps" /> the higher bioaccumulation factors were considered to be the more significant. The 2008 addendum<ref name="ECHA08" /> considered a further laboratory study from the Japanese [[Ministry of International Trade and Industry]] which was not available to the authors of the original Risk Assessment Report and which also showed bioaccumulation factors in fish (''[[Cyprinus]] carpio'') that were higher than the REACH threshold<ref name="REACHx13" /> of 5000 L/kg for "very bioaccumulative" substances. Bioaccumulation factors of more than 5000 L/kg (wet weight basis) have also been found in carp (''[[Carassius carassius]]'') and eels (''[[Anguilla anguilla]]'') from a sewage treatment pond.<ref>Gatermann ''et al.'' (2002).</ref> |
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