Reaction products of bis(4-methylpentan-2-yl)dithiophosphoric acid with phosphorus oxide, propylene oxide and amines, C12-14-alkyl (branched)

Endpoint summary

Description of key information

Ready biodegradation: Not readily biodegradable (ASTM D-5864-95).

Adsorption coefficient: The test substance is a mixture of components with log Koc values ranging from < 1.25 to 5.09 (EU Method C.19).

Additional information

Abiotic degradation; Hydrolysis

In accordance with Annex XI, the study does not need to be conducted if it is not scientifically possible to perform the test due to the properties of the test substance or because of analytical limitations of the test method. The test material is a complex UVCB consisting of a mixture of components with multiple functional groups that form complexes which it has not been possible to separate by chromatographic methods. Spectrometric methods such as IR detect functional groups but not individual components; mass spectrometry generates frgament ions rather than intact molecular ions. Additionally, the water solubility of this substance has been determined to be loading rate dependent and the composition of the substance in water might vary depending on loading. The lack of specificity of spectrometric methods and the lack of resolution by chromatographic methods limits our ability to detect or identify changes in this substance that can conclusively be attributed to hydrolysis.

Biodegradation in water: screening tests

The % biodegradation of the test material was determined according to guideline ASTM D-5864 -95. Activated sludge obtained from a domestic water treatment facility was adapted to the test material for 14 days under aerobic conditions. Following the acclimation, inoculated mineral medium was dosed with an amount of test substance equivalent to 10 mg carbon/L as the nominal sole source of organic carbon and aerated with CO2-free air. The CO2 produced within the test chambers was trapped as K2CO3 in KOH trapping solution.  At intervals between day 0 and day 28, a carbon analyzer was used to measure the amount of carbon in the trapping solution which was then mathematically converted to %ThCO2 (percent theoretical CO2). The results of the 28 day study indicate that the test substance is not readily biodegradable. The %ThCO2 of the test material was 3.6% ± 4.5 after 28 days. The %ThCO2 of the canola oil reference was 78.8% ± 0.4 after 28 days which validated the test.

Bioaccumulation

A bioconcentration study in rainbow trout was conducted according US EPA OPPTS 850.1730 and OECD 305 Guidelines using an analogue substance. Supply of test water: Continuous flow-through diluter system. The length of exposure was 97 days with 35 days uptake and 62 days depuration. The target concentrations were solvent control, 0.25 ug/L and 2.5 ug/L. The mean measured concentrations were <LOQ, 0.25 ug/L and 2.8 ug/L for the solvent control, low exposure level, and high exposure level respectively.

Based on the mean measured concentrations in water the Steady state BCF for the whole fish at the low exposure level was 426 (266-619 95% CI) and the steady state BCF for the whole fish in the high exposure level was 432 (210-571 95% CI). Steady-state concentrations of 14C-test material were achieved in the tissues of rainbow trout (Oncorhynchus mykiss) after 31 days. The mean measured water concentrations based on total radioactivity were 0.25 and 2.8 μg/L. Steady-state BCF values for the 0.25 μg/L test concentration, based on total radioactivity test material concentrations were 301, 625 and 436 in edible, non-edible and whole fish tissue, respectively. Steady-state BCF values for the 2.8 μg/L test concentration, based on total radioactivity test material concentrations were 260, 673 and 432 in edible, non-edible and whole fish tissue, respectively. Test material depurated slowly from fish tissue and consequently the study was terminated after reaching 62 days depuration, even though concentrations in the fish tissues remained above 10% of the steady state values. Because the declining concentrations in the tissues did not follow the first order assumptions kinetics required for valid kinetic estimates of BCF, the results of the derived kinetic BCF values were questionable and the steady state estimates of the BCF was considered to be the most accurate of the available BCF estimates from this study.