Cyclohexanepentanol, .beta.-methyl-

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:

2010-09-29 to 2010-10-27

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

, 1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

, 2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

, signed 2011-02-17

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
not applicable

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, Sunthelle 6, 57392 Schmallenberg, Germany (mainly fed with municipal wastewater)
- Method of cultivation: aerobic
- Storage conditions: kept aerobic until use
- Storage length: samples withdrawn on 2010-09-29
- Concentration of sludge: 29.6 mg dry mass/litre (7.39 mg dry mass/ 250 mL)

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Initial conc.:

20 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Remarks:

; the measurement and recording of the oxygen demand was carried out continuously using SAPROMAT respirometer (VOITH Inc.)

Details on study design:

TEST CONDITIONS
- Composition of medium: for the preparation of the stock solutions for mineral medium the following reagents (analytical grade) were used:
a) KH2PO4: 8.50 g/L; K2HPO4: 21.75 g/L; Na2HPO4 X 2 H20: 33.40 g/L; NH4Cl: 0.50 g/L
b) CaCl2 X 2 H2O: 36.40 g/L
c) MgSO4 X 7 H2O: 22.50 g/L
d) FeCl3 X 6 H2O: 0.25 g/L
Deionized water, free from inhibitory concentrations of toxic substances (e.g. Cu2+ ions) was used.
The mineral medium applied in the test contained 10 mL/L and 1 mL/L of the mineral stock solution a and b-d, respectively.

- Test temperature: 22 °C +/- 1 °C
- pH: before test start the pH values of all solutions were determined (7.4 +/- 0.2) and at the end of the test the pH values of all solutions were determined again (pH: 100 mg/L test item: 6.8 and 7.5; 20 mg/L test item: 7.5 and 7.6; inoculum blank: 7.6; abiotic control: 7.5 and 7.5; procedural control 8.2 and 8.3; toxicity control: 7.9 and 8.0).
- Continuous darkness: yes
- Other: the suspension was aerated during the whole test.

TEST SYSTEM
- Culturing apparatus: 500 mL glass vessels at a medium volume of 250 mL
- Number of culture flasks/concentration: 2 vessels containing 100 mg/l of the test item (25 mg/250 mL) and inoculum; 2 vessels 20 mg/L of the test item and inoculum

100 mg test item correspond to 304 mg ThOD, which is clearly above the demanded value of at least 50 - 100 mg ThOD/L. Some substances with high ThODs have gently inclined degradation curves, even when they are completely degradable. However, for these substances it is hard to reach the threshold value within the 10 -day window. Therefore, an additional assay with 20 mg test item (61 mg ThOD, therefore , meeting the required concentration of 50 - 100 mg ThOD/L) was conducted.

- Test performed in closed vessels
- Method used to create aerobic conditions: suspension was aerated during the whole test.
- Measuring equipment: measurement and recording of the oxygen demand was carried out continuously using SAPROMAT respirometer (VOITH Inc.)

SAMPLING
- Sampling frequency: measurement and recording of the oxygen demand was carried out continuously using SAPROMAT respirometer (VOITH Inc.)

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 vessels containing only inoculum
- Abiotic control: 2 vessels containing test item (100 mg/L and a sterilising inoculum
- Toxicity control: 2 vessels containing test item (100 mg/L), reference item (100 mg/L) and inoculum
- Procedural control: 2 vessels containing reference item (100 mg/L) and inoculum

STATISTICAL METHODS:
The theoretical oxygen demand was calculated on the basis of the sum formula of the test and reference item by ThOD [g/g] = 16 * (2 C + 1/2 H + 1/2 Na-O)/Molecular weight.
The ThOD values for Na-benzonate, the test item and the toxicity control were determined as follows:
ThOD (test item)): 3.04 mg O2/mg test item
ThOD (Na-benzoate): 1.67 mg O2/mg reference item
ThOD (toxicity control): 2.35 mg O2/mg substance mixture

The biochemical oxygen demand (BOD) was calculated on the basis of the test raw data by BOD [mg/mg] = mg O2 uptake corrected by blank per mg test item.
The percent degradation was calculated according to the following formula:
Dt = [(Ct - Cb)/ThOD] X 100
Dt: degradation (%) at time t;
Ct: mean oxygen consumption (mg/L) in the test suspension at time t;
Cb: mean oxygen consumption (mg/L) in the blanks at time t;
ThOD: Theoretical oxygen demand of the test suspension (mg/L).
No further information on the study design was stated.

Reference substance:

benzoic acid, sodium salt

Remarks:

Purity: 99 %; 100 mg/L medium

Preliminary study:

not applicable

Test performance:

No unusual observations during test.

Key result

Parameter:

% degradation (O2 consumption)

Value:

49

St. dev.:

2

Sampling time:

28 d

Remarks on result:

other: Concentration tested: 100 mg/L of the test material

Parameter:

% degradation (O2 consumption)

Value:

79

St. dev.:

7

Sampling time:

28 d

Remarks on result:

other: Concentration tested: 20 mg/L of the test material

Parameter:

% degradation (O2 consumption)

Value:

37

St. dev.:

2

Sampling time:

14 d

Remarks on result:

other: Concentration tested: 100 mg/L of the test material

Parameter:

% degradation (O2 consumption)

Value:

66

St. dev.:

11

Sampling time:

14 d

Remarks on result:

other: Concentration tested: 20 mg/L of the test material

Details on results:

The biodegradation within the 10-day-window was 72 % and 43 % in the assays with 20 mg/L and 100 mg/L, respectively. The 10-day-window starts at day 7 - 8 (20 mg/L) and day 8 (100 mg/L), respectively.

No abiotic degradation of the test item was noticable after 28 days of incubation. The biodegradation of the item mixture in the toxicity control was found to be 49 % after 14 days of incubation. Thus, the demanded threshold value of 25 % is exceeded and the test item can be identified as non toxic in a ready biodegradability test.

Due to a biodegradation of the test item below 60 % within the test duration, the test item at a concentration of 100 mg/L (ThOD of 304 mg O2/100 mg test item/L) failed the threshold value. Nevertheless, some substances with high ThOD have gently inclined degradation curves, even when they are completely degradable. For these substances it is hard to reach the threshold value within the 10 -day window. therefore, an additional assay with 20 mg test item (61 mg ThOD, therefore, meeting the required concentration of 50 - 100 mg ThOD/L) was conducted which passed the threshold of above 60 % biodegradtion in the 10 -day-window within a 28 day test duration.

In conclusion, according to the guideline, the test item can be identified as readily biodegradable under the chosen test conditions.

Validity and interpretation:
The test is considered valid, as
- the difference of extremes of replicate values of the removal of the test item at the end of the test was less than 20 %,
- the percentage degradation of the reference item has exceeded the pass level of 60 % by day 14,
- the oxygen uptake of the inoculum blank is < 60 mg/L in 28 days and the pH value was inside the range of 6.0 - 8.5.

Results with reference substance:

The reference item sodium benzoate was degraded to 82 % within the first 14 days.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

In conclusion, according to EU Method C.4-D (2008), the test item can be considered as readily biodegradable under the chosen test conditions.

Executive summary:

The biodegradability of the test item was tested according to EU Method C.4 -D (2008) at a concentration of 20 mg/L (61 mg ThOD) and 100 mg/L (304 mg ThOD) respectively. The biodegradation of the test item was found to be 79% after 28 days. The 10-d window was fulfilled (72 % biodegradation (20 mg test substance/L; ThOD 61 mg) that starts at day 7/8.

Hence, the substance is readily biodegradable under the test conditions. No inhibitory effects of the test item were observed (more than 25 % degradation occurred within 14 days) in the toxicity control.

Description of key information

Biodegradation in water - manometric respirometry test (OECD 301F; GLP compliant): readily biodegradable (79 % after 28 days). The 10-d window was fulfilled.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

One study on biodegradation in water was conducted. A manometric respirometry test (OECD 301F; GLP) was initiated with the test item resulting in 79 % degradation after 28 days (20 mg/L; ThOD 61 mg). The 10-d window was fulfilled (72 % biodegradation (20 mg test substance/L) that starts at day 7/8). As inoculum a non-adapted, domestic, activated sludge was used. The test item is considered to be readily biodegradable under the chosen test conditions.