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UNOXOL™ 3,4 Dialdehyde is considered readily biodegradable based on the following three separate biodegradation studies.

The first study was a Ready Biodegradability Closed Bottle Test – OECD 301D (Desmares-Koopmans, 2006). This study showed that UNOXOL™ 3,4 Dialdehyde was degraded significantly (54 and 59%, average 56.5%) during the 28-day test period. However, since 60% biodegradation was not reached within 10 days immediately following the attainment of 10% biodegradation (10 -day window), the strict criterion for ready biodegradability was not met. Therefore, under the conditions of this closed bottle test, UNOXOL™ 3,4 Dialdehyde was not considered to be readily biodegradable.

 

The second biodegradation study was a Manometric Respirometry Test - OECD 301F (West and Hales, 2007). The results of this study indicate that UNOXOL™ 3,4 Dialdehyde did pass the > 60% biodegradation at Day 28 and the 10-day window criteria for ready biodegradability. At the end of the 28-day test, the extent of biodegradation based on biochemical oxygen demand, CO2evolution, and dissolved organic carbon removal reached 81.6%, 65.2% and 96.7%, respectively. UNOXOL™ 3,4 Dialdehyde is a mixture of constitutional and stereo- isomers (cis- and trans- isomers of 1,3- and 1,4-cyclohexanedicarboxaldehyde) and the extent of degradation observed in this test indicates that all isomers were fully biodegraded. Under the conditions of this study and the strict OECD criteria, the UNOXOL™ 3,4 Dialdehyde components are readily biodegradable. Thus UNOXOL™ 3,4 Dialdehyde is expected to rapidly and completely biodegrade in a variety of aerobic environments.

 

An additional Manometric Respirometry Test (OECD 301F) was recently completed in China (Jing, 2012) to fulfill the regulatory requirement of China that biodegradation study needs to be conducted in China. Results of this study indicate that the mean biodegradation percentage for UNOXOL™ 3,4 Dialdehyde was 61.4% at day 28 and 53.5% at Day 19 (10-d window), which does not meet the 10-day window criteria. Therefore, under the conditions of this study and the strict OECD criteria, UNOXOL™ 3,4 Dialdehyde was not considered to be readily biodegradable.

 

Due to the stringent testing conditions for conducting these types of biodegradability tests, substances may sometimes fail individual tests when in reality these substances are readily biodegradable. OECD guideline Section 3 Introduction states that realizing ready biodegradability tests may sometimes fail because of the stringent test conditions, consistent positive test results from other test(s) should generally supersede negative test results (OECD, 2006).

 

Test results from the second biodegradability study (OECD 301F, West and Hales, 2007) indicate that UNOXOL™ 3,4 Dialdehyde did pass the “> 60% biodegradation at Day 28 and the 10-day window” criteria for ready biodegradability. The other two biodegradation studies showed that UNOXOL™ 3,4 Dialdehyde exhibited substantial biodegradation and it is close to be classified as “Readily Biodegradable”. Therefore, based on these three studies, UNOXOL™ 3,4 Dialdehyde met the strict criteria of “Readily Biodegradable” in the OECD 301F test and is expected to rapidly biodegrade in a variety of aerobic environments.