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Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Non-readily biodegradable

Hydrolysis rate at 50 °C, after 5 days: 96 % at pH 4, 9.6 % at pH 7, 98 % at pH 9

Koc: 2.962 l/kg; LogKoc: 0.4715

Additional information

The biodegradability of the substance was evaluated according to the ASTM E 1720 -01, which is similar to OECD Guideline 301B. Its biodegradation was determined on the basis of CO2 production. CO2 evolution was determined on the days 0, 3, 7, 10, 14, 17, 20, 24, 28. The test substance showed a biodegradation of 68.38 % after 28 days. This biodegradation level passed the level of 60 % indicated in both ASTM E1720 -01 and OECD 301 Guidelines. However, due to the fact that the 10 -day window requirement is not met, the substance can be considered as ultimately biodegradable meeting the ASTM requirement but it can be considered as non-readily biodegradable based on the requirements of both ASTM E1720 -01 and OECD 301. Additionally, according to Chapter R.7b: Endpoint specific guidance, Version 4.0 -June 2017: in certain cases when in the ready biodegradability tests the pass level criterion is fulfilled but the 10-day window criterion is not, this can be used as evidence for inherent biodegradability. To sum up, the substance is not readily biodegradable but could be considered as an ultimately, inherently biodegradable.

The hydrolysis profile of the substance was evaluated considering data on Similar Substance 01; justification for Read Across is given in section 13 of IUCLID. The substance appears to be hydrolytically stable at pH 7 while at pH 4 and pH 9 it could be hydrolysed by 96 % (at 50 °C, after 5 days) and 98 % (at 50 °C, after 5 days) respectively. Further investigation, showed that the half-lifes of the substance are as follows: at pH 4, 25 °C: 12 days; at pH 7, 25 °C > 1 year; at pH 9, 25 °C: 12 days. Envrironmental conditions suggest that the substance would be exposed to pHs ranging from values close to neutral pH to slightly basic pH values. The hydrolysis results suggest that an increase of pH value from 7 to 9 has a great impact on the hydrolytic behaviour of the substance. Therefore in neutral pHs the substance is considered to be very stable in contrast to basic pHs that the substance presents a half-time of 12 days. In combination with the biodegradation test (where the pH is usually ≈7.5) results, the substance is expected not to hydrolyse or to readily biodegrade in neutral pHs.

The adsorption coefficient (Log Koc) was predicted in the KOCKWIN model of EpiSuite v.4.11 and was found to be 0.4715 (Koc: 2.962 l/kg); this suggests a low potential for adsorption to soil and sediment.

The substance is thus expected to be present in the water phase and not the soil one, and thus available for the aquatic organisms. No bioconcenetration is though expected due to the predicted BCF of 1.41 l/kg. In the aqueous environment the substance is expected to biodegrade ultimately under aerobic conditions but is considered stable hydrolytically.

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