Fatty acids, C12-18 and C18-unsatd., reaction products with N,N-dimethyl-1,3-propanediamine and triethanolamine

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:

12.02.2019 - 13.03.2019

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)

Version / remarks:

CO 2 Evolution Test", (adopted July 17, 1992).

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and package No.of test material: lot #19953859
- Expiration date of the lot/batch: 16.01.2020

Oxygen conditions:

aerobic

Inoculum or test system:

other: Activated sludge from municipal wastewater treatment plant AZV Breisgauer Bucht

Details on inoculum:

Activated sludge from the municipal wastewater treatment plant AZV Breisgauer Bucht was used as inoculum with a concentration corresponding to 30 mg dry solids per litre. The treatment plant clarifies predominantly domestic wastewater and has a capacity of 600,000 inhabitant equivalents. Sampling date of activated sludge was on 11 February 2019. The dry solid content of the activated sludge was 4.4 g/L. It was determined by weight measurements after drying at 105°C for 3.25 hours (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 - <= 28 d

Initial conc.:

>= 20 - <= 20 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

In total three reactors containing the test item, three reactors containing only inoculum (blank) and three reactors containing the reference compound were set up. 10.2 mL activated sludge was filled up to 1500 mL with 1489.8 mL mineral medium corresponding to 30 mg/L dry solids. The system was sealed and aerated with CO 2 -free air overnight. The reactors were kept mixed with magnetic stirrers. On the next day, the absorber wash bottles were filled with 0.2 M NaOH and the test substance was added into the test vessels and into the toxicity control vessel. The reference compound was added into the reference vessels and into the toxicity control vessel. The aeration rate was kept at a rate of 30 - 100 mL / min (1.6 - 5.5 bubbles / second) and determined visually daily on working days. The determination by counting the gas bubbles over a defined period using a stop watch was made on days 2 and 27. The CO2 -free air production system, the air-tightness of the whole experimental set-up, the aeration of the absorber flasks and the magnetic stirrers were controlled daily on working days. At the beginning of the study the IC concentration of the 0.2 M NaOH used for the CO2 - absorption flasks was determined as 2.06 mg/L. The IC in the reactors at the beginning of the test was 0.679 mg/L. On the 3rd , 7th, 10th, 14th, 21st and 28th day 4 mL were sampled from the first of two CO 2 -absorber flasks connected in line and the IC's were determined. The vials were
immediately closed with sealing film in order to avoid CO 2 uptake from the air. On the 28th day, sampling of each reactor was performed to measure the CO2 dissolved in water as inorganic carbon (IC). The IC in the second CO2 -absorber flasks, used as protective flasks, was determined on day 29.

Reference substance:

benzoic acid, sodium salt

Test performance:

At the end of the test, a mean degradation extent of 82.9% of ThCO 2 was determined (28 days with considering the IC in the liquid phase, mean of three replicates, see table 1 and figure 1). For finding the exact position of the 10-d window the degradation values of day 3 to 7 and day 10 to 14 were calculated by interpolation. On day 4, the degradation was for the first time greater than 10%. Therefore, the end of the 10-d window is on day 14. On day 14, a mean degradation of 66.7% was calculated. Therefore, the test item reached the criteria for ready biodegradability (60% of ThCO2 within a 10-d window).

Key result

Parameter:

% degradation (CO2 evolution)

Value:

>= 82.9 - <= 82.9

St. dev.:

1.3

Sampling time:

28 d

Remarks on result:

other: readily biodegradable

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The substance reached the criteria for ready biodegradability (60% of ThCO2 within a 10-d window).

Executive summary:

At the end of the test, a mean degradation extent of 82.9% of ThCO 2 was determined (28 days with considering the IC in the liquid phase, mean of three replicates, see table 1 and figure 1). For finding the exact position of the 10-d window the degradation values of day 3 to 7 and day 10 to 14 were calculated by interpolation. On day 4, the degradation was for the first time greater than 10%. Therefore, the end of the 10-d window is on day 14. On day 14, a mean degradation of 66.7% was calculated. Therefore, the test item reached the criteria for ready biodegradability (60% of ThCO2 within a 10-d window).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

other: