7,7-dimethyl-3-oxa-6-azaoctan-1-ol

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Study conducted between 19th August 2005 to 14th October 2005

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study conducted in accordance with generally accepted scientific principles, possibly with incomplete reporting or methodological deficiencies, which do not affect the quality of the relevant results.

Qualifier:

according to guideline

Guideline:

other: ISO/TC 147/SC 5/WG 4N 141

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

other: natural seawater fortified with mineral nutrients- no additional innoculum added

Details on inoculum:

- Source of inoculum/activated sludge:
Raw seawater used for this study was supplied by a submersible pump situated on Sutherland's pier on the west side of Flotta in Scapa Flow.

- Method of cultivation:
This method uses natural seawater fortified with mineral nutrients and no innoculum is added in addition to the micr-organisms already present in the seawater.

- Storage conditions:
Three settlement tanks situated nine meters above floor level.

- Preparation of inoculum for exposure:
Five to Seven days before test commencement, the raw seawater passes by gravity through a 45 µm filter to the ageing tank.

- Water filtered: yes

- Type and size of filter used, if any:
45 µm filter

Duration of test (contact time):

28 d

Initial conc.:

2 mg/L

Based on:

test mat.

Initial conc.:

16 mg/L

Based on:

test mat.

Initial conc.:

50 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Remarks:

BOD measurements

Details on study design:

TEST CONDITIONS
- Test temperature:
20 ± 1°C

- Additional substrate:
KH2PO4 - 8.5
K2HPO4 - 21.7
Na2HPO4.2H2) - 29.92
NH4Cl - 0.5
CaCl2 - 31.84
MgSO4.7H2O - 22.5
FeCl3.6H2O - 0.25
EDTA - 0.4

TEST SYSTEM
- Culturing apparatus:
270 (±0.5) ml glass BOD bottles containing 180 ml test medium.

- Number of culture flasks/concentration:
1 per concentration

- Test performed in open system:
No, test bottles are sealed.


SAMPLING
- Sampling frequency:
Weekly

- Sampling method:
Measurement of BOD on the aqueous phase.


CONTROL AND BLANK SYSTEM
- Inoculum blank:
Background O2 consumption in test medium with clean silica powder.

- Toxicity control:
Mixture of the soluble reference substance compound and the test material.

STATISTICAL METHODS:
The overall assessment of biodegradability is based upon a compaison between experimentally-determined oxygen consumption (BOD measurements) and the oxygen consumption predicted if all carbon present in the test material were completely oxidised (theoretical oxygen demand, ThOD). Where the composition of the test material is known, or can be reasonably inferred, the ThOD can be calculated from the empirical formula and the molecular weight:

ThOD of CcHhOcNn = 16[2c+0.5(h-3n)-o] / MW mgO2mg-1

The extent of biodegradation is estimated from the cumulative BOD relative to the theoretical oxygen consumption if 100% of the material was fully mineralised during the test (calculated from the theoretical oxygen demand and the amount of test material addedd to the test vessel).

Thus; % biodegradation of ThOD is: ΣBOD*100/test material concentration*ThOD
where:
ThOD = theoretical oxygen deman in mgO2/mg substance
ΣBOD = cumulative BOD after n (weekly) measurements in mg O2

ΣBOD is calculated from: ΣUr*Oc
where:
Ur = relative uptake of oxygen in the water phase defined as:Ur = Cbt-Ct / Cs
Cbt = dissolved oxygen concentration in blank after incubation at time t in mg O2/litre
Ct = dissolved oxygen concentration in test after incubation at time t in mg O2/litre
Cs = saturation value for dissolve oxygen at normal atmospheric pressure at 20°C (usually 7.45 mg/litre)
ΣUr = sum of Ur values after n measurements
Oc = total oxygen capacity of the flasks equal to the maximum oxygen content in gas plus liquid at normal atmospheric pressure at 20°C in mg O2/flask

Oc is calculated from: Oc = Vair*0.280 + V1*0.008
where:
Vair = volume of air in the flask in ml
V1 = volume of liquid in the flask in ml
0.280 = oxygen content in mg/ml of normal air
0.008 = oxygen content in mg/ml of saturated water

Reference substance:

benzoic acid, sodium salt

Preliminary study:

Not applicable.

Test performance:

Formal validity criteria:
Temperature : 20°C ± 1
Reference substance degradation: >60% in 14 days
Cumulative blank oxygen consumption: <30% of oxygen initially available

Actual results
Temperature : 20°C ± 1
Reference substance degradation: 86% in 14 days
Cumulative blank oxygen consumption: not recorded

The test was conducted in accordance with the study plan and met all relevant validity criteria. There were no interferences in this test.

Parameter:

% degradation (O2 consumption)

Value:

69

Sampling time:

28 d

Remarks on result:

other: Test material concentration 2mg/l showed an inhibition of 40% to seawater bacteria.

Parameter:

% degradation (O2 consumption)

Value:

95

Sampling time:

49 d

Remarks on result:

other: Test material concentration 2mg/l

Parameter:

% degradation (O2 consumption)

Value:

13

Sampling time:

28 d

Remarks on result:

other: Test material concentration 16mg/l showed an inhibition of 9% to seawater bacteria.

Parameter:

% degradation (O2 consumption)

Value:

5

Sampling time:

28 d

Remarks on result:

other: Test material concentration 50mg/l showed an inhibition of 17% to seawater bacteria.

Details on results:

The test material at 2mg/l biodegraded by 69% over 28 days and showed an inhibition of 40% to seawater bacteria. The test was exetended for an additional 28 days to establish whether degradation was continuous after the test period. The test material achieved a maximum biodegradation of 95% on day 49 of the 56 day study.

Parameter:

BOD5

Value:

1.7 mg O2/g test mat.

Results with reference substance:

The reference substance degraded by more than 60% (86%) in the first fourteen days, indicating that the seawater used in the test contained a satisfactory population of viable bacteria.

Summary table of results

Test material	Test material	Test material	Test material
Behaviour in seawater	soluble	soluble	soluble
ThOD (mg O2.mg-1)	1.23	1.23	1.23
Addition rate (mg/l)	2	16	50
% inhibition (Day 28)	40%	9%	17%
% biodegradation (Day 28)	69%	13%	5%
Final 56 Day biodegradation	85%	21%	8%

Validity criteria fulfilled:

yes

Remarks:

Outlined in Test Performance section

Interpretation of results:

readily biodegradable

Conclusions:

The test substance at 2mg/l biodegraded by 69% over 28 days and showed an inhibition of 40% to seawater bacteria. The test was exetended for an additional 28 days to establish whether degradation was continuous after the test period. EC9016A achieved a maximum biodegradation of 95% on day 49 of the 56 day study.

Executive summary:

Study number 697 -18 was commissioned to determine the aerobic degradability in seawater (Marine BODIS test, ISO/TC 147/SC 5/WG 4N 141) of the test substance at three different addition rates, 2 mg/l, 16 mg/l and 50 mg/l.

The test substance at 2mg/l biodegraded by 69% over 28 days and showed an inhibition of 40% to seawater bacteria. The test was exetended for an additional 28 days to establish whether degradation was continuous after the test period. The test substance achieved a maximum biodegradation of 95% on day 49 of the 56 day study.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

Study was conducted between 30/08/2004 and 24/11/2004

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The test material used for this study is identified as insoluble in water. However, the conducted Water Solubility study (4.8 of this IUCLID 5 dossier) has shown that the substance is soluble at 25 °C. The method used for this study has been chosen on the basis that the substance is insoluble in water. Therefore, due to this deviation, this study can only be identified as 3 - Not Reliable.

Qualifier:

equivalent or similar to guideline

Guideline:

ISO Draft (BOD Test for Insoluble Substances)

Version / remarks:

BODIS 1995

Deviations:

yes

Principles of method if other than guideline:

The Norwegian Pollution Control Authority (SFT) has not yet decided upon which procedure should be required for biodegradation testing of insoluble substances. Pending further notice, SFT has approved the above mentioned test system (at time of study completion).

Biodegradation testing has been performed on the test substance based on a modified seawater variant of ISO TC/147, SC5/WG4 N141: BOD Test for Insoluble Substances (BODIS)".

GLP compliance:

yes (incl. QA statement)

Remarks:

GLP No. 42653

Oxygen conditions:

aerobic

Inoculum or test system:

other: Seawater medium

Duration of test (contact time):

56 d

Initial conc.:

14 other: µl/flask

Based on:

test mat.

Parameter:

other: BOD related to ThOD, or related to COD

Value:

9

Sampling time:

56 d

Details on results:

Table 1 (attached) presents the results from the biodegradation testing of the test substance. Figure 1 (attached) shows the biodegradation curve of the test substance. The raw data are presented in Appendix 1 (Attached).

Parameter:

BOD5

Value:

6.9 - 7.1 mg O2/g test mat.

- Validation criteria:

According to the validation criteria, a test is considered valid if the percentage degradation of the reference substance (inoculum control) has reached the level of 60% ThOD within 14 days. THe reference substance was degraded by 75% within 14 days and the activity of the inoculum was, therefore satisfactory. The respiration in the blank did not exceed the validation criteria for the test. The microbal colony count was within the validation range.

The BOD of the mixture of test and reference substance (C. i. a.) was not equal to the sum of BOD of the separate solutions of the two substances. That indicated that the test substance can be considered to be inhibitory to bacteria at the concentration used. A repitition of this test with lower concentrations will not necessarily give an increase in the biodegradability of the test substance.

The test is considered to be valid.

Validity criteria fulfilled:

yes

Remarks:

Please see Overal Remarks in the results section for details.

Interpretation of results:

other: Not readily biodegradable

Conclusions:

A test substance has a potential for biodegradation in the marine environment if it has been degradaed 60% within 28 days.

The test substance was degraded by 9% after 56 days. Based on this, the test substance cannot be characterised as readily biodegradable in the marine environment.

Executive summary:

Biodegradation testing has been performed on the test substance based on a modified seawater variant of ISO TC/147, SC5/WG4 N141: BOD Test for Insoluble Substances (BODIS)".

The test substance was degraded by 9% after 56 days based on COD calculations and measurements to account for O2 consumption. The results were also corrected for oxygen consumption due to nitrification.

A test substance has a potential for biodegradation in the marine environment if it has been degradaed 60% within 28 days. The test substance cannot be characterised as readily biodegradable in the marine environment.

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

Not reported in the data over 12 years old provided by ECHA.

Reliability:

other: Reliability of study not reported in the data over 12 years old provided by ECHA.

Qualifier:

according to guideline

Guideline:

other: OECD Guideline No 301 C

Deviations:

not specified

GLP compliance:

yes

Duration of test (contact time):

28 d

Parameter:

% degradation (TOC removal)

Value:

5

Sampling time:

28 d

Validity criteria fulfilled:

not specified

Interpretation of results:

other: not readily biodegradable

Conclusions:

The test substance is not regarded as readily biodegradable.
Ready Biodegradability by:-
i) TOC, 4%
ii) HPLC, 2%

Reference 4

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

Not reported in the data over 12 years old provided by ECHA.

Reliability:

other: Reliability of study not reported in the data over 12 years old provided by ECHA.

Qualifier:

according to guideline

Guideline:

other: Principles of method if other than guideline ->

Deviations:

not specified

GLP compliance:

yes

Duration of test (contact time):

28 d

Initial conc.:

400 mg/L

Based on:

test mat.

Reference substance:

other: Sodium benzoate

Parameter:

other: degradation

Value:

84

Sampling time:

28 d

Details on results:

Experimental values (test substance):

15% degradation after 1d
24% degradation after 2d
76% degradation after 3d
82% degradation after 5d
81% degradation after 12d
84% degradation after 28d

Results with reference substance:

Experimental values (reference substance):
38% degradation after 1d
45% degradation after 2d
85% degradation after 3d
94% degradation after 5d
98% degradation after 12d
100% degradation after28d

Interpretation of results:

inherently biodegradable

Conclusions:

The test substance degraded 84% after 28 days and therefore is inherently biodegradable.

Description of key information

Biodegradation rate is >60% in 28 days according to the key study. 
Further studies classed as ‘not reliable’ or of unreported reliability gave the following results
9% over 56 days in seawater
84% over 28 days
5% over 28 days

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

In the only reliable screening test presented for biodegradation in water (Hudson, 2005), the substance met the relevant criteria for ready biodegradability. The test substance biodegraded by 69% over 28 days despite causing inhibition of 40% to seawater bacteria. The test was exetended for an additional 28 days to establish whether degradation was continuous after the test period and the substance achieved a maximum biodegradation of 95 % on day 49 of the 56 day study.