1,4,10,13-pentaoxacyclopentadecane

Biodegradation in water: screening tests

Administrative data

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

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2022

Report date:

2022

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EU Method C.4-A (Determination of the "Ready" Biodegradability - Dissolved Organic Carbon (DOC) Die-Away Test)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

1,4,10,13-pentaoxacyclopentadecane

EC Number:

251-379-6

EC Name:

1,4,10,13-pentaoxacyclopentadecane

Cas Number:

33100-27-5

Molecular formula:

C10H20O5

IUPAC Name:

1,4,7,10,13-pentaoxacyclopentadecane

Specific details on test material used for the study:

Substance ID: 15-Crown-5
Lot #: 1909004
Purity: 96.9%

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

other: aerobic activated sewage sludge from the aeration stage of the local wastewater treatment plant

Details on inoculum:

- Source of inoculum/activated sludge: Local wastewater treatment plant, ARA Birs (Birsfelden / Switzerland), which treats predominantly domestic sewage
- Pretreatment: No pre-adaptation of the inoculum to the test item was done
- Preparation of Inoculum: The aerobic activated sewage sludge was washed three times by centrifugation, decantation of the supernatant liquid phase and resuspension of the solid material in tap water and finally in mineral medium as representative for the test system. Aliquots of the homogenized final sludge suspension were weighed, thereafter dried and the dry weight of the suspended solids was determined.
Based on this determination, a calculated amount of wet sludge was suspended in mineral medium to obtain a concentration equivalent to 4 g dry material per liter. During the holding period of two days prior to use, the sludge was aerated at room temperature. Prior to use, the dry weight was determined again. Based on this determination defined amounts of the activated sludge suspension were added to mineral medium to obtain a final concentration of 30 mg dry material per liter.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

>= 59 - <= 59.3 mg/L

Based on:

test mat.

Remarks:

to result in a test concentration of approximately 30 mg DOC/L in the test vessels

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Composition of medium: The following stock solutions obtained by dissolving analytical grade salts in ultrapure water were used:
1) KH2PO4 8.50 g/L
K2HPO4 21.75 g/L
Na2HPO4 × 2H2O 33.40 g/L
NH4Cl 0.50 g/L
The pH of this solution was 7.4.
2) CaCl2 × 2H2O 36.40 g/L
3) MgSO4 × 7H2O 22.50 g/L
4) FeCl3 × 6H2O 0.25 g/L, stabilized with one drop of concentrated HCl per liter.
To obtain 1 L of the final mineral medium, 10 mL of stock solution No. 1 and 1 mL each of stock solutions Nos. 2, 3 and 4 were added to approximately 800 mL ultrapure water, mixed and made up to 1000 mL with ultrapure water. The pH was adjusted from 7.6 to 7.4 with a diluted hydrochloric acid solution.
- Test temperature: 22 °C
- pH: Prior to test start (Day 0), the pH was measured in each test vessel before the addition of the inoculum, and if necessary, adjusted to pH 7.4 using a diluted sodium hydroxide solution.
- pH adjusted: Yes
- Light conditions: The test vessels were incubated in diffused lighting


TEST SYSTEM
- Culturing apparatus: 2000-mL Erlenmeyer glass vessels, cleaned with alcoholic hydrochloric acid, rinsed with ultrapure water and dried. The test vessels were filled to a volume of 1000 mL. Each vessel was loosely covered with an aluminum cap to reduce losses by evaporation.
- Number of replicates: 2
- Measuring equipment: DOC analyses were performed using a TOC infrared gas analyzer equipped with an automatic sampler

SAMPLING
- Sampling frequency: Test item and inoculum control: Exposure Day 0, 3, 5, 7, 10, 12, 14, 19, 21 and 28;
Procedure control: Exposure Day 0, 3, 7, 14 and 28;
Toxicity control: Exposure Day 0, 7, 14 and 28;
- Sampling method: For the DOC analyses, one sample of about 10 mL was taken from each sampled test vessel per sampling occasion.
- Sample preparation: Samples were filtered through a 0.45-μm filter. The first 2-3 mL of the filtrate were discarded. Thereafter, the samples were immediately analyzed for DOC.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
- Toxicity control: Yes

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

Test performance:

The results are considered to be valid, since the following criteria are met:
- The difference between the degradation values of the replicate test vessels containing the test item was 1 % to 15 % throughout the test (criterion: less than 20 % at the plateau, at the end of the test or at the end of the 10-day window).
- The percentage degradation of the reference item, sodium benzoate, reached with 96 % by Exposure Day 3 the pass level for ready biodegradability (criterion: at least 70 % in a 10-day window by Day 14).

Further:
- The test item is considered to be non-inhibitory, since the toxicity control attained 59% degradation by Day 14 (criterion: ≥ 35% degradation by Day 14).

% Degradation

% Degradation 1

Key result

Parameter:

% degradation (DOC removal)

Value:

12

Sampling time:

28 d

Remarks on result:

other: not readily biodegradable

% Degradation 2

Parameter:

% degradation (DOC removal)

Value:

17

Sampling time:

10 d

Remarks on result:

other: pass level for ready biodegradability in a 10-day window within the 28-day period of the test, was not reached

Details on results:

Biodegradation of the Test Item:
In the test vessels containing the test item in inoculated mineral medium, the mean concentration of dissolved organic carbon (DOC) continuously decreased from initially 30 mg/L on Day 0 to 25 mg/L on Day 10. Afterwards it remained at approximately the same level until the end of the test on Day 28. Expressed as percentage DOC removal, this represents a mean biodegradation value of 17 % on Day 10 and 12 % on Day 28. However, the pass level for ready biodegradability, i.e. at least 70 % removal of DOC in a 10-day window within the 28-day period of the test, was not reached.

Biodegradation in the Toxicity Control:
In the toxicity control, containing both test item (corresponding to 52% of total DOC) and the reference item sodium benzoate (corresponding to 48% of total DOC) in inoculated mineral medium (mineral medium + activated sludge), the initial DOC concentration of 62 mg/L measured on Day 0 decreased to 25 mg/L on Day 14. Biodegradation amounted to 59% within 14 days of exposure. By the end of the test (Exposure Day 28), average biodegradation was 57 %.
Thus, according to the test guidelines, the test item was not inhibitory to activated sludge at the tested concentration of 59 mg/L, because degradation of the sum of both test and reference item was >35% within 14 days.

Measurement of pH and Dissolved Oxygen Concentration:
All vessels started the test with a pH of 7.4. At the end of exposure (Day 28), pH values of 7.2–7.4 were measured.
The dissolved oxygen concentration was found to be in the range of 8.4 to 8.5 mg O2/L for all vessels at test start. At the end of exposure (Day 28), values of 8.5 to 8.7 mg O2/L were measured.

BOD5 / COD results

Results with reference substance:

In the procedure controls, average biodegradation of the reference item sodium benzoate was 99% by Exposure Day 14, thus confirming suitability of the activated sludge (≥ 70 % degradation by Exposure Day 14). By the end of the test (Exposure Day 28), the reference item was degraded completely.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test item was not readily biodegradable under the test conditions within 28 days.

Executive summary:

The test item was investigated for its ready biodegradability in a 28-Day DOC Die-Away Test according to the guideline OECD 301 A, EC Method C.4-A and US EPA OPPTS 835.3110.

In the test vessels, containing the test item in inoculated mineral medium, the mean concentration of dissolved organic carbon (DOC) continuously decreased from initially 30 mg/L on Day 0 to 25 mg/L on Day 10. Afterwards it remained at approximately the same level until the end of the test on Day 28. Expressed as percentage DOC removal, this represents a mean biodegradation value of 17 % on Day 10 and 12 % on Day 28. However, the pass level for ready biodegradability, i.e. at least 70 % removal of DOC in a 10-day window within the 28-day period of the test, was not reached.

In conclusion, the test item was not readily biodegradable under the test conditions within 28 days.

In the toxicity control, containing both the test item and the reference item sodium benzoate, the initial DOC decreased by 59 % within 14 days of exposure. Thus, the test item had no inhibitory effect on the activity of activated sludge microorganisms at the tested concentration of 59 mg/L.

In the procedure controls, average biodegradation of the reference item was 99% by Exposure Day 14, thus confirming suitability of the activated sludge (≥ 70 % degradation by Exposure Day 14). By the end of the test (Exposure Day 28), the reference item was degraded completely.