Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Hydrolysis:The estimated half-life at 25 °C of the research material was shown to be greater than 1 year at pH 4, 7 and 9 (OECD 111 and EU Method C.7).

Biodegradation:The research material attained 65% biodegradation after 28 days and satisfied the 10-Day window validation criterion, whereby 60 % biodegradation must be attained within 10 days of the biodegradation exceeding 10 %. The research material can therefore be considered to be readily biodegradable (OECD 301 B).

Adsorption coefficient:The adsorption coefficient of the research material was determined to be < 17.8 with Log10 Koc < 1.25 (OECD 121 and EU Method C.19).

Additional information

Abiotic degradation; Hydrolysis

Assessment of hydrolytic stability was carried out in a key study using Method C.7 Abiotic Degradation, Hydrolysis as a Function of pH of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.

The test system consisted of buffer solutions at pH 4, 7 and 9. The buffer solutions were passed through a 0.2 μm membrane filter to sterilise and subjected to ultrasonication and degassing with nitrogen to minimise dissolved oxygen. Duplicate sample solutions were taken initially and from the water bath at various time points. The pH of each solution recorded. The concentration of test item in the sample solutions was determined by high performance liquid chromatography (HPLC).

 

Stock solutions of test item were prepared at a nominal concentration of 1.0 x10E03 mg/L in the three buffer solutions. At this concentration the pH 4 stock precipitated. It was therefore passed through a filter paper and the filtrate diluted by a factor of 2 with the pH 4 buffer solution. This produced a stock solution than was half saturation as required by the test guidelines.

 

The stock solutions were split into individual glass vessels, sealed with minimal headspace, for each data point. These sample solutions were shielded from light whilst maintained at the test temperature. Sample solutions at pH 4, 7 and 9 were maintained at 50.0 ± 0.5 °C for a period of 120 hours.

 

The estimated half-life at 25 °C of the research material was shown to be greater than 1 year at pH 4, 7 and 9.

Biodegradation

A key 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 the 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)).

The test item, at a concentration of 10 mg carbon/L, was exposed to activated sewage sludge micro-organisms with mineral medium in sealed culture vessels in the dark at temperatures of between 22 and 25 °C for 28 days. biodegradation of the test item was assessed by the 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 research material attained 65% biodegradation after 28 days and satisfied the 10-Day window validation criterion, whereby 60 % biodegradation must be attained within 10 days of the biodegradation exceeding 10 %. The research material can therefore be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301B.

Adsorption coefficient

 

The key determination was carried out using the HPLC screening method, designed to be compatible with Method C.19 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001.

 

The test utilised a High Performance Liquid Chromatograph. A commercially available cyanopropyl reverse phase HPLC column containing lipophilic and polar moieties was used. The dead time was determined by measuring the retention time of formamide (purity quoted by supplier: 99.94 %) at 615 mg/L in methanol. Solutions of reference standards were prepared in methanol and the test item (0.0536 g) was diluted to 100 mL with methanol:water (55:45 v/v) to give a concentration of 0.536 g/L.

The adsorption coefficient of the research material was determined to be < 17.8 with Log10 Koc < 1.25