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Hydrolysis:

Hydrolysis study was read-across to MAES.

Hydrolysis was assessed with regards to stability.

The determination was carried out using Method C7 of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/548/EEC).

The kinetics of the study have been determined to be consistent with that of a pseudo-first order reaction as the graphs of log10 concentration versus time are straight lines. It has been observed that the rate of hydrolysis increases with an increase in pH. The hydrolysis pathway was anticipated to be base catalysed hydrolysis/cleavage of the test material at either of the two ester bonds. Therefore possible primary hydrolysis products may be, but not limited to: • Butanedioic acid • 2 -Propenoic acid, 2 -hydroxyethyl ester • 2-Propenoic acid • Butanedioic acid, mono 2-hydroxyethyl ester.

It has been observed that the rate of hydrolysis increases with an increase in pH.

The rate constant and estimated half-life at 25°C of the test material are shown in the following table:

pH

Rate Constant (s-1)

Estimated Half-life at 25oC

4

2.72 x 10-8

295 days

7

5.13 x 10-8

156 days

9

4.14 x 10-6

46.5 hours

The estimated half-life at 25oC 295 days (pH = 4), 156 days (pH = 7) and 46.5 hours (pH = 9) indicates that significant exposure to the parent compound in the environment over a long period of time is not of significant concern.

Biodegradation:

A study was performed to assess the ready biodegradability of the test material in an aerobic aqueous medium. The method followed that described in the OECD Guidelines for Testing of Chemicals (1992) No 301B, "Ready Biodegradability; CO2 Evolution Test" referenced as Method C.4-C of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/548/EEC), and US EPA Fate, Transport, and Transformation Test Guidelines OPPTS 835.3110 Paragraph (m).

The test material, at a concentration of 10 mg Carbon/l, was exposed to activated sewage sludge micro-organisms with culture medium in sealed culture vessels in the dark at 21°C for 28 days. The degradation of the test material was assessed by the determination of carbon dioxide produced. Control solutions with inoculum and the standard material, sodium benzoate, together with a toxicity control were used for validation purposes.

The test material attained 22% degradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No 301B.

Partition Coefficient: Partition Coefficient, 45.6 (log10 Pow 1.66), was determined using the HPLC method, Method A8 of Commission Directive 92/69/EEC.

Adsorption Coefficient:

No determination of the adsorption coefficient was possible by the HPLC estimation method, Method C19 of Commission Directive 200l/59/EC as the method is not valid for organic acids. Therefore in place of experimental data, an estimate of the adsorption coefficient was obtained by calculation using Quantitative Structure Activity Relationships (QSAR's), the details of which are provided in the technical guidance documents in support of Commission Directive 93/67/EEC on risk assessment for new substances. Using a QSAR calculation, the adsorption coefficient of the test material was estimated to be log10 Koc 1.32.