Potassium hexadecyl hydrogen phosphate

Endpoint summary

Additional information

Biodegradation in water

Biodegradation of potassium hexadecyl hydrogen phosphate in water was examined in two studies in a weight of evidance approach. The first study which was performed according to OECD guideline 310 showed that the test substance is not readily biodegradable (37 % after 28 days) and the second study that was performed according to OECD guideline 302C showed that the test item is inherently biodegradable (86 % after 28 days).

 

The ready biodegradability was determined with a non-adapted activated sludge for potassium hexadecyl hydrogen phosphate over a test period of 28 days in the Headspace Test. The study was conducted according to OECD 310. Potassium hexadecyl hydrogen phosphate was tested with a concentration of 35 mg/L in triplicates, corresponding to carbon content (TOC) of 18.4 mg C/L in the test vessels. The biodegradation of the test item was followed by TIC analyses of the quantity of CO2 produced by the respiration of bacteria. The amount of TIC produced was calculated by correcting the results of the test and reference item for endogenous TIC production of the control groups.

The 10 % level (beginning of biodegradation) was reached after 12 days. The pass level of 60 % was not reached during the test period. The biodegradation of the test item came to a maximum of 37 % after 28 days. The 95 % confidence interval on day 28 was 32 - 42 %.

The percentage degradation of the functional control (activity of the test system sodium benzoate) reached the pass level of 60 % after 3 days and came to 87 % after 28 days. The 95 % confidence interval on day 28 was 83 - 91 %. The validity criteria according to the guideline were fulfilled.

The test item is considered to be primarily inherently biodegradable under the test conditions.

 

The inherent biodegradability of potassium hexadecyl hydrogen phosphate was determined by the manometric respirometry test according to the OECD guideline 302C. A measured volume of inoculated mineral medium, containing 30 mg/L test substance as the nominal sole source of organic carbon, was stirred in a closed flask at a constant temperature (± 1 °C) for up to 28 days. The consumption of oxygen was determined by measuring the quantity of oxygen required to maintain constant the gas volume in the respirometer flask. The amount of oxygen taken up by the microbial population during biodegradation of the test chemical (corrected for uptake by blank inoculum, run in parallel) was expressed as a percentage of ThOD. Potassium hexadecyl hydrogen phosphate undergoes an average of 86 % biodegradation after 28 days under the test conditions. Biodegradation proceeds steadily from the first day to the last, suggesting that solubilisation or hydrolysis is the limiting rate factor. Thus, potassium hexadecyl hydrogen phosphate was regarded as ultimately inherently biodegradable according to this test.

In conclusion, based on the weigh of evidance approach the test item is classified as inherently biodegradable.

Biodegradation in water and sediment

In accordance with column 2 of REACH annex IX, further degradation testing does not need to be conducted as potassium hexadecyl hydrogen phosphate was shown to be inherently biodegradable in a screening test. Thus, further simulation tests will not improve the chemical safety assessment. Safe use was shown for the developed exposure scenarios (CSR section 9 and 10).

Biodegradation in soil

In accordance with column 2 of REACH annex IX, further degradation testing does not need to be conducted as potassium hexadecyl hydrogen phosphate was shown to be inherently biodegradable in a screening test. Thus, further simulation tests will not improve the chemical safety assessment. Safe use was shown for the developed exposure scenarios (CSR section 9 and 10).