3,7-dimethyloct-1-en-3-ol

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12.09.2014 - 26.11.2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

GLP study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2014

Report date:

2014

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

3,7-dimethyloct-1-en-3-ol

EC Number:

242-358-2

EC Name:

3,7-dimethyloct-1-en-3-ol

Cas Number:

18479-49-7

Molecular formula:

C10H20O

IUPAC Name:

3,7-dimethyloct-1-en-3-ol

Test material form:

liquid

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

aerobic activated sludge from a wastewater treatment plant (ARA Ergolz II, Füllinsdorf, Switzerland) treating predominantly domestic wastewater

Duration of test (contact time):

28 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

100 mg/L

Based on:

test mat.

Initial test substance concentration 2

Initial conc.:

298 other: mg O2/L test solution

Based on:

ThOD

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

The test design and test system are consistent with the testing guidelines and should provide a rational basis to assess the ready biodegradability of the test item under aerobic conditions.
The study was performed with aerobic activated sludge from a wastewater treatment plant (ARA Ergolz II, Füllinsdorf, Switzerland) treating predominantly domestic wastewater. The sludge was washed twice with tap water by centrifugation and the supernatant liquid phase was decanted. A homogenized aliquot of the final sludge suspension was weighed, thereafter dried and the ratio of wet to dry weight was calculated.
Based on this ratio, calculated amounts of wet sludge were suspended in test water (see below) 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 sludge was first thoroughly mixed and then diluted with test water to a concentration of 1 g per liter (dry weight basis). Based on the determined dry weight of this diluted activated sludge, defined amounts were added to test water to obtain a final concentration of 30 mg dry material per liter.

Test Water

The test water was prepared according to the testing guidelines. Analytical grade salts were dissolved in purified water to obtain the following stock solutions:
1) KH2PO4 8.50 g/L
K2HPO4 21.75 g/L
Na2HPO4 x 2H2O 33.40 g/L
NH4Cl 0.50 g/L
The pH of this solution was 7.4.
2) MgSO4 x 7H2O 22.50 g/L
3) CaCl2 x 2H2O 36.40 g/L
4) FeCl3 x 6H2O 0.25 g/L, stabilized with one drop of concentrated HCl per liter.
To obtain the final test water, 10 mL of stock solution No. 1 and 1 mL each of stock solution Nos. 2, 3 and 4 were combined and made up to 1000 mL with purified water. The pH was adjusted from 7.9 to 7.4 with a diluted hydrochloric acid solution.

Test Concentrations

Approximately 25 mg test item was added to the designated test flasks with test water. No emulsifiers or solvents were used.
The reference item sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. A stock solution containing 2.5 g sodium benzoate per liter test water was prepared by completely dissolving 250 mg sodium benzoate in 100 mL test water. From this stock solution, 10 mL aliquots were added to the corresponding test flasks containing test water.
Finally, activated sludge was added to each test flask. The final test volume was 250 mL per test flask.

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

Preliminary study:

not applicable

Test performance:

The results are considered to be valid since the following criteria are met:
- The degradation rates of the replicate test flasks containing the test item, test water and inoculum deviated by less than 20% at the end of the 10-day window and at the end of the test (criterion: not more than 20% deviation at the end of the 10-day window, at the time the plateau is reached or at the end of the test, as appropriate).
- The percentage degradation of the reference item reached the level for ready biodegradability by Day 3 (criterion: at least 60% of ThOD in a 10-day window by
Day 14 for the reference item).
- The mean oxygen demand of the inoculum control (medium and inoculum) was 8 mg O2/L within 28 days (criterion: normally 20-30 mg O2/L, but not greater than
60 mg O2/L).
- The pH was in the range 7.5 – 7.9 in all flasks after 28 days of exposure (criterion: not outside the range 6.0 – 8.5).

% Degradation

Key result

Parameter:

% degradation (O2 consumption)

Value:

61

Sampling time:

28 d

Remarks on result:

other: Indication of inherent biodegradability

Details on results:

The percent biodegradation of the test item was calculated based on the theoretical oxygen demand (ThOD) of 2.97 mg O2/mg test item.

The biochemical oxygen demand (BOD) of 3,7-dimethyloct-1-en-3-ol in the test media significantly increased from Exposure Day 6 until Day 9. Afterwards the increase of the BOD was less intense, but continued during the whole test period. At the end the test, on Exposure Day 28, the mean biodegradation of 3,7-dimethyloct-1-en-3-ol amounted to 61% of the ThOD. A plateau of the biodegradation curve was not reached.

BOD5 / COD results

Results with reference substance:

In the toxicity control, containing both 3,7-dimethyloct-1-en-3-ol and the reference item sodium benzoate, the biodegradation amounted to 43% and 64% by Exposure Day 14 and 28, respectively. Therefore, the test item had no inhibitory effect on the activity of activated sludge microorganisms at the tested concentration of 100 mg/L.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable

Conclusions:

The test item 3,7-dimethyloct-1-en-3-ol was found to be not readily biodegradable in a manometric respirometry test over 28 days according to the OECD Guideline for Testing of Chemicals No. 301 F, Commission Regulation (EC) No 440/2008, C.4-D and the US EPA Draft Ecological Effects Test Guidelines OPPTS 835.3110 (Paragraph (q)).
However, according to paragraph 36 of the Revised Introduction to the OECD Guidelines for Testing of Chemicals, Section 3 (2006), the obtained result of 61% biodegradation within 28 days, can be used to indicate inherent biodegradability of 3,7-dimethyloct-1-en-3-ol.

Executive summary:

The test item 3,7-dimethyloct-1-en-3-ol was investigated for its ready biodegradability in a manometric respirometry test over 28 days according to the OECD Guideline for Testing of Chemicals No. 301 F, Commission Regulation (EC) No 440/2008, C.4-D and the US EPA Draft Ecological Effects Test Guidelines OPPTS 835.3110 (Paragraph (q)).

The percent biodegradation of the test item was calculated based on the theoretical oxygen demand (ThOD) of 2.97 mg O2/mg test item.

The biochemical oxygen demand (BOD) of 3,7-dimethyloct-1-en-3-ol in the test media continuously increased from Exposure Day 6 until the test end. The mean biodegradation of 3,7-dimethyloct-1-en-3-ol amounted to 61% of the ThOD at the end of the test, on Exposure Day 28, and a plateau of the biodegradation curve was not reached.

Since, the pass level for ready biodegradability, i.e. biodegradation of at least 60% of the ThOD in a 10-day window within the 28-day period of the test, was not reached, the test item was found to be not readily biodegradable. However, the obtained result of 61% biodegradation within 28 days, can be used to indicate inherent biodegradability of 3,7-dimethyloct-1-en-3-ol.

In the toxicity control, containing both 3,7-dimethyloct-1-en-3-ol and the reference item sodium benzoate, the biodegradation amounted to 43% and 64% by Exposure Day 14 and 28, respectively. Therefore, the test item had no inhibitory effect on the activity of activated sludge microorganisms at the tested concentration of 100 mg/L.

In the procedure controls, the reference item sodium benzoate was degraded by an average of 61% and 82% by Exposure Day 3 and 14, respectively and reached 84% by the end of the test (Day 28), thus confirming suitability of the activated sludge.