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Environmental fate & pathways

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Abiotic degradation; Hydrolysis

Test guidelines for hydrolysis are not, in general, recommended for complex mixtures because components could have different hydrolytic rates that give rise to non-pseudo first order hydrolysis plots. In addition, hydrolysis products can be analytically indistinguishable from the starting components because larger components hydrolyse to hydrolysis products that have the same structure as components already within the test item. Furthermore, the test item is a complex, surface active, UVCB where the components exist as ion pairs and this fact would be expected to add further complexity to any experimental system used as a method of describing hydrolysis. Nevertheless, a conclusion on hydrolysis potential can be drawn from data disseminated by ECHA for the environmentally relevant amine discussed in this dossier [EC 273-279-1] because hydrolytic stability of the components in that substance were found to be consistent with the absence of hydrolytically susceptible functional groups. It can therefore be predicted that the UVCB described in this dossier is likely to be hydrolytically stable (half-life at 25 °C > 1 year) at pH 4, 7, and 9.


A study was performed to assess the ready biodegradability of the test item in an aerobic aqueous medium. The method followed was designed to be compatible with OECD Guidelines for Testing of Chemicals (1992) No 301B "Ready Biodegradability; CO2 Evolution Test" referenced as Method C.4 -C of Commission Regulation (EC) No 440/2008 and US EPA Fate, Transport, and Transformation Test Guidelines OCSPP 835.3110 (Paragraph m).

An initial experiment was conducted at a concentration of 10 mg carbon/L. The toxicity control vessel, containing both the test item and sodium benzoate, attained less than 25% biodegradation after 14 days. These results indicated that, under the strict terms and conditions of the OECD guidelines, the test item would be classed as exhibiting inhibitory effects.

Therefore, following the recommendations of the Test Guidelines, in the definitive test, the test item at a reduced concentration of 5 mg Carbon/L was exposed to activated sewage sludge micro-organisms with culture medium in sealed culture vessels in the dark at 20 to 22 °C for 28 days.

The biodegradation of the test item was assessed by determination of carbon dioxide produced. Control solutions with inoculum and the reference item, sodium benzoate, together with a toxicity control were used for validation purposes.

The test item attained 24 % biodegradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301B.

Adsorption / desorption coefficient (Koc)

Experimental determination of adsorption coefficient was not possible because the test item is a complex, surface active, UVCB where the components exist as ion pairs. Log Koc for the environmentally relevant constituent of the test item was therefore predicted using EPISUITE (KOCWIN v2.00). The Log Koc range calculated was 3.74 to 3.80.