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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Readily biodegradability data from OECD 301B or 301F testing for a series of closely related trimellitate esters indicate that the submission substance, CAS No. 70225-05-7, would expected to be inherently biodegradable.  

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable

Additional information

Ready biodegradability studies have been carried out for a series of closely related trimellitate esters including the ester reaction products of branched tridecanol, isodecanol and trimellitic anhydride (CAS No. 70225-05-7).  The results indicate that the biodegradability of these materials can vary considerably, ranging from <5% to 46.8% in 28 days and to as much as 60.9% in 39 days. The submission substance was found to biodegrade <2% in a 28 day ready biodegradation test. By comparison, tri-2-ethylhexyl trimellitate (CAS No. 3319-31-1) has been reported to be biodegraded from 3.4 to 46.8% biodegradation in 28 days and as much as 60.9% in 39 days. The exact reasons for the wide variation among study results are unclear, but contributing factors may include low water solubility of the trimellitate esters which could limit their bioavailability or access/contact to microbial enzymes in the aqueous solution carrying out hydrolysis and metabolism/breakdown. Other variables such as degree of agitation/mixing, test material bioavailability/contact with microbial population in the test system, slow initial hydrolysis rate, as well as variation in inoculum and interlaboratory testing. Overall, the trimellitate ester materials were not readily biodegradable (>60% in 28 days). The overall evaluation of the available data suggest that the trimellitate esters are expected to be at least inherently biodegradable under favorable environmental conditions. This appears to be consistent with the recent SIDS evaluation by the US EPA that trimellitate ester HPV chemicals as a general chemical category are sufficiently biodegradable and are not expected to be persistent or bioaccumulative (US EPA 2009). 

 

Based on the above data considerations, trimellitate esters such as ester reaction products of branched tridecanol, isodecanol and trimellitic anhydride (CAS No. 70225-05-7) would be expected to be inherently biodegradable in the standard OECD ready biodegradability test.