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Environmental fate & pathways

Endpoint summary

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Description of key information

Four OECD 301B studies are available for the substance. Of the four only one failed to reach 60% mineralisation by the end of the test. In a GLP study by Bellemain (2011) a total of 44.5 and 37.5% mineralisation was achieved on the 29thday falling short of the required 60% mineralisation and failing the 10 day window. Nevertheless, a review of the biodegradation plot reveals a lag time between 10 and 14 days prior to onset of biodegradation followed by a shallow degradation curve typical of highly insoluble substances which are poorly bioavailable and therefore only slowly degraded. There is no plateau at 29 days with a steady increase in mineralisation from days 18 to 29 from 20 to 40%. The toxicity control mirrors the activity observed in the test solutions.

In the three other studies:

1.     64.7% biodegradation was achieved in a 28 d GLP study by Schaefer & Matthews (2011) although the 10 day window was not met. Once again, Squalane was subject to a long lag phase of 10 days before the onset of mineralisation and this was once again followed by a linear mineralisation rate without a plateau as in the previous study, suggesting that the hydrophobicity of the substance is the rate limiting factor

2.     66.3% biodegradation was attained in a non-GLP OECD 301B study BfB (2011). Again, there was a long lag time of 11 days prior to onset of biodegradation and a near linear mineralisation over the study such that the 10 d window was not achieved

3.     77% biodegradation was achieved at the end of an ISO 17025 certified OECD 301B test, which should be considered the Key study, this time reaching the 10 day window. Once again a significant lag phase of 10 days was observed but the rate of mineralisation was more rapid than that found in the preceding studies. It should be noted that the ISO 17025 certification is not GLP but shares many aspects of this accreditation and for the purposes of this study should be considered comparable to GLP.Accreditation toISO/IEC 17025 demonstrates technical competence, therefore laboratories that are accredited to this standard are demonstrating that they follow 'good laboratory practice' and that the data produced is technically valid.

 

Based on the above information, the substance can be considered as readily biodegradable  

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