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EC number: 939-526-9 | CAS number: 90506-73-3
Biodegradation in water: screening tests
Administrative data
Link to relevant study record(s)
Description of key information
The biodegradation of Phosphoric acid, mono- and di- C16-18 (even numbered) alkyl esters has been investigated in a Modified Sturm Test and a Modified MITI Test (II). The substance was found to be inherently biodegradable.
Key value for chemical safety assessment
- Biodegradation in water:
- inherently biodegradable
Additional information
The biodegradation of Phosphoric acid, mono- and di- C16-18 (even numbered) alkyl esters has been assessed in a Modified Sturm Test. As in this test the substance was found to be not readily biodegradable, a Modified MITI Test (II) to test the inherent biodegradation was performed.
The ready biodegradability of Phosphoric acid, mono- and di- C16-18 (even numbered) alkyl esters was determined with a non-adapted activated sludge over a test period of 28 days in the Modified Sturm Test according to OECD 301 B. The test item was tested at a concentration of 20 mg/L with 2 replicates, corresponding to a carbon content (TOC) of 13.4 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. To check the activity of the test system, sodium benzoate was used as functional 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 19% was determined after 6 days and it came to 38% after 28 days.
For the 2nd replicate, containing 100 mg/L test item and 20 mg/L reference item, a biodegradation of 7% was determined after 6 days and it came to 15% 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 21. The 60% pass level was not reached after 28 days. The mean biodegradation after 28 days was 15%.
The test item is classified as not readily biodegradable in the 10-d-window and after 28 days.
The inherent, ultimate biodegradability of Phosphoric acid, mono- and di- C16-18 (even numbered) alkyl esters, was determined according to OECD guideline 302 C (12 May 1981) in the Modified MITI Test (II) over a test period of 60 days using non adapted activated sludge from a municipal sewage tretment plant as inoculum. The test item concentration was 25 mg/L, corresponding to a ThOD of 67.3 mg O2/L. Aniline was used as functional control. The functional control reached the pass level of > 65% after 22 days in the mean of both replicates. The mean biodegradation rate was 42% on day 7 and 50% on day 14. It came to a biodegradation rate of 100% after 28 and 60 days.Although the pass level of ≥ 65% biodegradation was only reached on day 22, the biodegradation curve showed the typical course for an activated sludge with high biodegradation potential. Instead of the original MITI (II) inoculum activated sludge with nitrification potential was used. The oxygen consumption by nitrification occurs frequently with a time shift, as nitrification only starts when carbon oxidation is advanced. Due to this time shift, the 65% pass level is reached with a delay.
The test item replicates did reach the 10% level (beginning of biodegradation) within 19 days. The pass level > 70% for evidence of inherent, ultimate biodegradability was neither reached within 28 days nor within 60 days. One of the three replicates reached 69% biodegradation after 60 days, whereas the other two replicates reached 33% and 28%, respectively. After 28 days the mean biodegradation rate was 18% and after 60 days it was 43%.
Under the test conditions reported, Phosphoric acid, mono- and di-C16-18 (even numbered) alkyl esters was not inherently, ultimately biodegradable, but inherently, primarily biodegradable within 60 days.
In summary, Phosphoric acid, mono- and di- C16-18 (even numbered) alkyl esters is considered to be inherently biodegradable.
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