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Biodegradation in water: screening tests

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Description of key information

Phosphoric acid, mono- and di-C11-14 (linear and branched) alkyl esters is inherently, ultimately biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable

Additional information

The ready biodegradability of Phosphoric acid, mono- and di-C11-14 (linear and branched) alkyl esters was determined with a non adapted activated sludge over a test period of 28 days in the Modified Sturm Test. The study was conducted from 2012-06-07 to 2012-07-06 according to OECD 301 B at Dr.U.Noack-Laboratorien. The test item was tested at a concentration of 20 mg/L with 2 replicates, corresponding to a carbon content (TOC) of 11.14 mg C/L in the test vessels. The biodegradation of the test item was followed by titrimetric analysis of the quantity of CO2 produced by the respiration of bacteria. The degradation was stopped on day 28 by acidification of the test solutions. The last titration was made on day 29, after residual CO2 had been purged from the test solutions over a period of 24 hours. The percentage CO2 production was calculated in relation to the theoretical CO2 production (ThCO2) of the test item. The biodegradation was calculated for each titration time.

To check the activity of the test system, sodium benzoate was used asfunctional control. The percentage degradation of the functional control reached the pass level of 60% within 9 days and a biodegradation of 76% after 28 days.

The toxicity control contained both test item, in different concentrations, and reference item. For the 1st replicate, containing 20 mg/L test item and 20 mg/L reference item a biodegradation rate of 26% was determined after 6 days and it came to 56% after 28 days.

For the 2nd replicate, containing 100 mg/L test item and 20 mg/L reference item a biodegradation of 10% was determined after 6 days and it came to 36% after 28 days. The biodegradation of the reference item was not inhibited by the test item at 20 and 100 mg/L in the toxicity control.

The mean 10% level (beginning of biodegradation) was reached on day 18 by both replicates. The 60% pass level was not reached after 28 days. The mean biodegradation after 28 days was 20%.

The test item was not readily biodegradable in the 10-d-window and after 28 days.

 

The inherent biodegradability ofPhosphoric acid, mono- and di-C11-14 (linear and branched) alkyl esterswas determined in the Modified MITI Test (II) with non adapted activated sludge for a period of 40 days. The study was conducted from 2012-12-04 to 2013-01-21, with the definitive exposure phase from 2012-12-11 to 2013-01-21, according to OECD Guideline 302 C at Dr.U.Noack-Laboratorien, 31157 Sarstedt, Germany. The test item concentration selected as appropriate was 30 mg/L, corresponding to a ThOD of 66.9 mg O2/L. The oxygen was depleted by respiration of bacteria and the degradation was followed by measuring the oxygen concentration. The biodegradation is therefore expressed as the percentage BOD depletion and was calculated for each study day.

The mean oxygen depletion in the inoculum control was 107 mg O2/L on day 28 and 115 mg O2/L on day 40.

In order to check the activity of the test system, Aniline was used as functional control. The functional control reached the pass level of > 40% after 4 days and > 65 % after 9 days in the mean of both replicates. It came to a biodegradation rate of 100% after 20 days.

The test item replicates did reach the 10% level (beginning of biodegradation) within 3 days. The pass level > 70% for evidence of inherent, ultimate biodegradability was reached within 34 days. After 28 days the mean biodegradation rate was 64% and 76% after day 40, respectively.

Under the test conditions, Phosphoric acid, mono- and di-C11-14 (linear and branched) alkyl esters was inherently, ultimately biodegradable within 40 days.