Phosphoric acid, C14-15-branched and linear alkyl esters, potassium salts

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Name: Phosphoric acid, C14-15 branched and linear alkyl esters, potassium salts
CAS No.: 1893414-79-3
Physical state: white solid at 20 °C
Batch No.: PU61810016
Re-certification date of batch: 09 March 2018
Purity: 100 % (UVCB, lyophilized solid, water content 0.85 % (w/w))
Stability: stable under test conditions
Storage condition of test material: Room temperature, protected from light

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Activated sludge from the municipal wastewater treatment plant Breisgauer Bucht (Forchheim, Germany) was used as inoculum with a concentration corresponding to 30 mg dry solids per litre. The treatment plant clarifies predominantly domestic wastewater of the region of Freiburg and has a capacity of 600.000 inhabitant equivalents. Sampling date of activated sludge was 2 November 2016. Dry solid of the activated sludge was determined as 3.9 g/L by weight measurements after 3 h drying at 105 °C (mean of triplicate measurements). The activated sludge was washed twice with tap water by settling the sludge, decanting the supernatant and re-suspending the sludge.

Duration of test (contact time):

28 d

Initial conc.:

>= 98.9 - <= 101.7 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation:

O2 consumption

Reference substance:

acetic acid, sodium salt

Test performance:

- The difference of extremes of replicate values was less than 20%.
- The biodegradation of the reference item reached the pass level of 60% ThOD by day 4.
- The degradation extent in the toxicity control was above 25% in 14 days based on ThOD.

Key result

Parameter:

% degradation (O2 consumption)

Value:

46.7

Sampling time:

28 d

Details on results:

Validity criteria:
- The oxygen uptake of the inoculum blank was below 60 mg O2/L within 28 days.
- The pH value in the test and blank bottles was 7.6 at the end of the test.
- The difference of extremes of replicate values was less than 20%.
- The biodegradation of the reference item reached the pass level of 60% ThOD by day 4.
- The degradation extent in the toxicity control was above 25% in 14 days based on ThOD.

Results with reference substance:

The reference compound sodium acetate reached the pass level for ready biodegradability (≥ 60% ThOD and fulfilment of the 10-day window) within 8 days (see table 2). The pH in the test bottles at the end of the test was 9.1.

Test item:

The biodegradation of the test item was 46.7% within 28 days (mean of three replicates).

Therefore the test item did not reach the criteria for ready biodegradability according the OECD criteria (≥ 60% ThOD and fulfilment of the 10-d window). The pH in the test bottles at the end of the test was 7.6.

Reference item:

The reference compound sodium acetate reached the pass level for ready biodegradability (≥ 60% ThOD and fulfilment of the 10-day window) within 8 days (see table 2). The pH in the test bottles at the end of the test was 9.1.

Toxicity control:

The degradation in the toxicity control reached 25.5% within 4 days and was thus above the criterion for inhibition effects to the inoculum (<25% on day 14). The test item had no toxic effect to the inoculum according to the validity criteria of OECD 301. The pH in the vessel was 8.7.

Blank:

The oxygen consumption of the blanks was 29.0 mg/L in 28 days (mean of three replicates). The pH in the vessels was 7.6.

Temperature:

The temperature range was 21.8 – 22.8 °C throughout the whole study.

Discussion of the results

The elementary analysis (performed by ASG Analytic Service GmbH) showed the following results: C = 53.7%; H = 9.91%; P = 8.75%; O = 5.8% (complete = 78.16%). Out of this a ThOD of 2.91 mgO2 / mg test item could be calculated.

Obviously an amount of 21.84% is missing to get the complete composition of the test item. According to the information from the sponsor the test item should have a considerable content of potassium. For calculating the ThOD we assumed therefore that the potassium content is 21.84%. This leads to a ThOD of 2.35 mg O2/ mg test item. The evaluation was therefore performed with the ThOD of 2.35 mg O2 / mg test item. Nevertheless the degradation extent calculated with both ThOD-contents would give results under 60%. The overall result would not be influenced by a more detailed elementary analysis.

Biodegradation in % of ThOD

	Test item			Toxicity control	Reference item
Test item [mg/164 ml]	7.1	6.9	7.1	7.1
Reference item [ml/164 ml]				164	164	164	164
ThoD [mg/l]	101.7	98.9	101.7	201.7	100.0	100.0	100.0
Day
0	0	0	0	0	0	0	0
4	-1.8	3.8	0.9	25.5	51.5	51.5	48.7
8	-0.9	7.6	1.8	33.0	63.8	66.6	66.6
12	4.6	16.1	10.2	38.4	75.1	75.1	75.1
16	8.4	31.4	13.9	43.5	75.7	78.7	73.2
20	21.2	47.5	24.0	48.5	77.8	80.8	77.8
24	31.4	57.9	34.1	53.5	79.8	82.8	79.8
28	40.6	56.0	43.4	58.0	81.0	78.0	75.0

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The degradation extent of the test item at the end of the test was 46.7% (mean of three replicates). The criterion for ready biodegradation was not met (degradation ≥ 60% and fulfilment of 10-d-window) therefore the test item is not ready biodegradable according to the OECD criteria.

Executive summary:

In a OECD 301 f study the degradation extent of the test item at the end of the test was 46.7% (mean of three replicates). The criteria for the validity of the study were met. The criterion for ready biodegradation was not met (degradation ≥ 60% and fulfilment of 10-d-window) therefore the test item is not ready biodegradable according to the OECD criteria.

Description of key information

The degradation extent of the test item at the end of the test was 46.7% (mean of three replicates).  The criterion for ready biodegradation was not met (degradation ≥ 60% and fulfilment of 10-d-window) therefore the test item is not ready biodegradable according to the OECD criteria.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable