Phosphoric acid, C11-14 (C13-rich)-isoalkyl mono- and di-esters, partially salted with 1-Propanamine, 3-(tridecyloxy)-, branched

Endpoint summary

Description of key information

The test item attained 0 % biodegradation after 28 days and therefore cannot be considered to be readily biodegradable (OECD 301 B).

Additional information

Abiotic degradation; Hydrolysis

Determination of hydrolytic stability was not carried out 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 due to the test item having overall low solubility in aqueous media and being a complex mixture. The water solubility of the test item, at which all components would dissolved, was expected to be too low to perform the test as a sensitive enough analytical method was not available. Additionally, the test solution would need to be half this concentration to satisfy the test requirements. The test item, being a complex mixture, was not ideally suited to the test method. This is because components that are unstable could have significantly different hydrolytic rates, and if there are components that are stable also, this would lead to conflicting results. Additionally, hydrolysis products of complex mixtures can be the same as some of the components already present and differentiating these would not be possible. Based on the main amine, ether and phosphate ester functional groups, it was considered that the test item would not readily hydrolyse at environmentally relevant pH and temperature.

 

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; CO2Evolution 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 21 and 24 °C for 28 days. Following the recommendations of the International Standards Organisation (ISO 1995) and the published literature (Handleyet al, 2002), the test item was adsorbed onto granular silica gel prior to dispersion in the test medium to aid dispersion of the test item in the test medium and to increase the surface area of the test item exposed to the test organisms.

 

The 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 test item attained 0% 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)

Determination of adsorption coefficient was not 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, as the test item was considered to be not applicable to the method and that any result produced would likely be inaccurate. Some of the components in the test item contain an amine functional group. These amines would be ionised throughout the environmentally relevant pH range forming cations, which could be subjected to cationic exchange with soils. This mode of adsorption can be significantly stronger than that of adsorption to the organic content of the soil. As the HPLC method does not take into consideration the effect of cationic exchange, the results can be underestimated. Additionally, amines undergo secondary interactions with silica based HPLC columns due to the silanol groups and this also can add to the uncertainty of the result. The HPLC estimation method is generally consider not applicable to highly surface active substances such as the registered substance. For example, surface active substances can form micelles in an aqueous environment but these would not form in the same way in the organic solvent environment of the test. Overall it was considered that the HPLC method would lead to significant uncertainty in any result generated and for that reason the test was not performed. For purposes of risk assessment, the absorption coefficient was estimated using available data and EUSES version 2.1.2.