Amines, C12-14-alkyl, C6-10-alkyl phosphates

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

yes

Remarks:

Deviations from the Guideline: Temperature range was 19.5 – 21.2 °C instead of 20.0 – 24.0 °C. As degradation of the positive control was in the normal range, this is considered as uncritical con-cerning the outcome of the study

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

6.3 Test System
6.3.1 Specification
Activated sludge from a biologic sewage treatment plant was used as inoculum. The cho-sen plant treats mostly domestic sewage.
6.3.2 Source and Pre-Treatment of inoculum
6.3.2.1 Source
The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant, Im Altenschemel, NW-Lachen-Speyerdorf.
Date of collection: 12. Jan. 2018, batch no: 20180112.
6.3.2.2 Pre-Treatment
The sludge was filtrated, washed with test medium (2x) and re-suspended in test medium. It was then aerated until use. The dry matter was determined to contain 4900 mg of sus-pended solids/L.

Duration of test (contact time):

28 d

Initial conc.:

32.6 mg/L

Based on:

other: calculation

Key result

Parameter:

% degradation (CO2 evolution)

Value:

76

Sampling time:

28 d

Details on results:

The 10-day-window began on day 5, at its end, 46 % degradation were reached (graphical evaluation), missing the pass level of 60 % given in the OECD guideline. If a test on the mixture is performed and it is anticipated that a sequential biodegradation of the individual structures is taking place, then the 10-day. Because the test item is a mixture, the 10-day window has not to be taken into account. Therefore, regardless of the 10-day-window the test item is considered as “readily biodegradable within 28 days”.

1      Results and Validity

1.1     Results for the Test ItemDeophos 228

¨            The test itemDeophos 228is considered as “readily biodegradable“.

¨            The degree of biodegradation reached 76 % after 28 days.

¨            The 10-day-window began on day 5, at its end, 46 % degradation were reached (graphical evaluation), missing the pass level of 60 % given in the OECD guideline.

¨            

If a test on the mixture is performed and it is anticipated that a sequential biodegradation of the individual structures is taking place, then the 10-day
window should not be applied to interpret the results of the test.

Therefore the Test substance is considered as “readily biodegradable within 28 days”.

¨            The abiotic degradation reached 3.5 %.

1.2     Validity

All validity parameters and values are presented in the following table:

Table9.2‑a      Validity

Parameter	Criterion	Found	Assessment
IC content of test item solution in medium	£5% of TC	0 %	valid
CO2emitted by the controls	< 70 mg/L	8.9 mg/L	valid
Difference within replicates	£20%	0.8 %	valid
Degradation of positive control > 60%	≤14 days	9 days	valid
Degradation in the toxicity flask on day 14	> 25%	71.1 %	non-toxic

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

All validity criteria were met. Degradation behaviour of positive control and toxicity control was normal. Abiotic degra-dation reached 3.5 %. Both replicates of the test item showed very good correspondence. Degradation values of more than 100 % were calculated. This is due to the fact that the measurement errors of test flasks and control flasks add up when using the equation proposed in the guidelines. If degradation in the toxicity flask is below 25 % after 14 days, the test item can be considered as toxic towards the inoculum. As degradation in the toxicity flask was 71.1 % after 14 days, the test item can be stated as “not toxic towards the inoculum in a concentration of 32.6 mg/L”. For pure substances ready biodegradability is defined in the guidelines as degradation surpassing 60 % within 10 days after reaching a level of 10 %. The 10-day-window began on day 5, at its end, 46 % degradation were reached, missing the pass level of 60 % given in the OECD guideline. If a test on the mixture is performed and it is anticipated that a sequential biodegradation of the individual structures is taking place, then the 10-day window should not be applied to interpret the results of the test. Because the test item is a mixture, the 10-day window has not to be taken into account. Therefore, regardless of the 10-day-window the test item is considered as “readily biodegradable within 28 days”. No observations were made which might cause doubts concerning the validity of the study outcome. The result of the test can be considered valid.

Executive summary:

The test substance was tested at a nominal concentration of 20 mg organic carbon/L (corresponding to 32.2 mg test substance/L) in test medium following OECD 301B and EU-Method C.4 -C. 

Aniline was chosen as positive control. Activated sludge was used as inoculum (concentration in the test 25.0 mg dry matter/L). The test was left running for 28 d. All validity criteria were met. Degradation of the positive control was 80% after 9 d. The following data were determined for the test substance:

degradation at the end of the test                                                                                            76%

As degradation surpassed 60% in the course of the test, the test substance is considered as readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The test substance was tested at a nominal concentration of 20 mg organic carbon/L (corresponding to 32.2 mg test substance/L) in test medium following OECD 301B and EU-Method C.4 -C. 

Aniline was chosen as positive control. Activated sludge was used as inoculum (concentration in the test 25.0 mg dry matter/L). The test was left running for 28 d. All validity criteria were met. Degradation of the positive control was 80% after 9 d. The following data were determined for the test substance:

degradation at the end of the test                                                                                            76%

As degradation surpassed 60% in the course of the test, the test substance is considered as readily biodegradable.