Dodecanoic acid, ester with 1,2,3-propanetriol

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)

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

GLP compliance:

yes (incl. QA statement)

Remarks:

Ministerium für Arbeit, Integration und Soziales des Landes Nordrhein-Westfalen

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Sewage treatment plant Ruhrverband Kläranlage, Schmallenberg, Germany (February 14th, 2017)
- Preparation of inoculum for exposure: The sludge was washed in mineral medium and centrifuged (at 1100 g for 10 minutes). The supernatant was discarded. The concentrated sludge was suspended in mineral medium to a concentration of 2.6 g suspended solids/L. The sludge was aerated with CO2-free air over night to purge the system of carbon dioxide. A sample was withdrawn just before use for the determination of the dry weight of the suspended solids.
- Concentration of sludge: 29 mg dry mass/litre (87 mg dry mass/3 L)

Duration of test (contact time):

28 d

Initial conc.:

20 mg/L

Based on:

other: ThOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral medium
- Test temperature: 22 °C (± 2 °C)
- pH: 7.4 of mineral medium
- Aeration of dilution water: with CO2-free air
- Suspended solids concentration: 29 mg/L in the final 3 litres
- Continuous darkness: yes
- Other: To each test vessel 2400 mL mineral medium was added. A volume of 34.3 mL of the prepared activated sludge to give a concentration of suspended solids of 29 mg/L in the final 3 litres of inoculated mixture was added. After aeartion with CO2-free air overnicht, two absorption bottles, each containing 200 mL of 0.05 M sodium hydroxide solution were connected in series to each 5-litre flask. Test item was added on a weight basis. The volume of suspensions in all flasks was filled up to 3 litres by the addition of mineral medium.

TEST SYSTEM
- Culturing apparatus: 5-litre flasks
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: The vessels were aerated by the passage of carbon dioxide free air at a controlled rate during the incubation period.
- Test performed in closed vessels due to significant volatility of test substance: yes
- Details of trap for CO2 and volatile organics if used: The CO2 is trapped in sodium hydroxide and is measured as inorganic carbon.

SAMPLING
- Sampling frequency: Days of sampling for CO2 measurement were day 2, 5, 9, 12, 14, 21, 28, and 29.
- Sampling method: The samples of suspensions (IC measurement) were filtered through ROTH PET filters (0.45 μm) as soon as they are taken. The samples of the hydroxide absorbers were measured without any manipulation to avoid CO2 enrichment.
The measurements of the TIC concentration were carried out using a TC analyser (Shimadzu TOC-V-CPH).
- Sample storage before analysis: Analysis was done directly after sampling.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2
- Abiotic sterile control: 1
- Toxicity control: 1

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (CO2 evolution)

Value:

99

Sampling time:

28 d

Results with reference substance:

In the positive control, 79% was degraded after 14 d confirming the suitability of the inoculum.

In the toxicity control, more than 25% biodegradation occurred within 14 days (83.7%). Therefore, the test item was assumed not to inhibit microbial activity.

Table 1: Percent degradation (IC) after 14 days. Degradation (%) on the basis of IC in the sodium hydroxide traps after 14 days of incubation.Single and mean values of the replicates and standard deviation.

vessel	Test suspension	Abiotic control	Procedural control	Toxicity control
1	75.0	0.3	79.1	83.7
2	86.4
Mean	80.7	0.3	79.1	83.7
SD	8.0

 

Table 2: Percent degradation (IC) after 28 days. Degradation (%) on the basis of IC in the sodium hydroxide traps after 28 days of incubation and the following acid dissolving. Single and mean values of the replicates and standard deviation.

vessel	Test suspension	Abiotic control	Procedural control	Toxicity control
1	96.4	-2.5	84.4	96.5
2	102.4
Mean	99.4	-2.5	84.4	96.5
SD	4.2

 

Table 3: Validity criteria for OECD 301B

Criterion from the guideline	Outcome	Validity criterion fulfilled
Difference of extremes of replicate values of the removal of the test chemical at the plateau, at the end of the test or at the end of the 10-d window, as appropriate, is less than 20%.	With 6 % the difference of extremes of replicate values of the removal of the test item at the end of the test was less than 20 %.	yes
Percentage degradation of the reference compound has reached the pass levels by day 14.	The percentage degradation of the reference item has exceeded the pass level of 60 % by day 14.	yes
The toxicity control should degrade to at least 35% (based on DOC) or at least 25% (based on ThOD or ThCO2) within 14 d.	The biodegradation of the item mixture in the toxicity control was found to be 84 % after 14 days of incubation.	yes
The IC content of the test substance suspension in the mineral medium at the beginning of the test must be less than 5% of the TC.	With 2.0 %, the mean IC content in the mineral medium of the suspensions containing test item at the beginning of the test fall below the demanded threshold value of 5 % of the TC.	yes
The total CO2 evolution in the inoculum blank at the end of the test should not normally exceed 40 mg/L medium.	With 16.0 mg CO2 per liter (4.4 mg C/L), the total CO2 evolution in the inoculum blank at the end of the test is below the demanded value.	yes

 

Validity criteria fulfilled:

yes

Remarks:

For further details please refer to “Any other information on results incl. tables”.

Interpretation of results:

readily biodegradable

Conclusions:

The pass level of 60% was reached in a ready biodegradation test (OECD 301B) within 28 days. The 10-day window was reached. Thus, the substance is readily biodegradable.

Description of key information

Readily biodegradable: 99% in 28 d (CO2 evolution), OECD 301B

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

One study is available investigating the ready biodegradability Dodecanoic acid, ester with 1,2,3-propanetriol (CAS 37318-95-9). This study was conducted according to OECD 301B (GLP) using activated sludge from a municipal sewage treatment plant being exposed to the test substance at a concentration of 20 mg/L ThOC for 28 days. After 28 days, the test substance reached 99% biodegradation based on Co2 evolution. The 10-day window was met. No inhibitory effects of the test item were observed in the toxicity control (more than 25 % degradation occurred within 14 days). Thus, the substance is readily biodegradable according to the OECD criteria.