4-Decenal, 9-hydroxy-5,9-dimethyl-

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:

22 March to 13 June 2013

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)

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3210 (Inherent Biodegradability: Modified SCAS Test)

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage (Bois-de-Bay, Satigny, Switzerland)
- Method of cultivation: The sludge is collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernatant and resuspending in mineral medium) and kept aerobic until being used on the same day.

Duration of test (contact time):

38 d

Initial conc.:

30 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium:
The following stock solutions were prepared:
Solution A:
KH2PO4: 8.5 g
K2HPO4: 21.75 g
Na2HPO4 2 H2O: 33.4 g
NH4Cl: 0.5 g
dissolved in water and made up to 1 litre.

Solution B:
CaCl2: 27.5 g
dissolved in water and made up to 1 litre.

Solution C:
MgSO4 7 H2O: 22.5 g
dissolved in water and made up to 1 litre.

Solution D:
FeCl3 6 H20: 0.25 g
HCI Conc.: one drop
dissolved in water and made up to 1 litre.

Mineral medium is prepared by mixing 50 ml of solution A and 2000 ml deionised water, adding 5 ml of each of the solutions B, C and D and making up to 5 litres with deionised water. The pH is measured and if necessary adjusted to 7.4 ± 0.2 with phosphoric acid or potassium hydroxide.

- Test temperature: 21.9°C - 22.2°C
- pH: 7.5 – 7.9
- Suspended solids concentration: 4.74 g/L

TEST SYSTEM
- Culturing apparatus: The respirometer - Oxitop Control System, made by Wissenschaftlich-Technische Werkstatten (WTW), Weilheim, Germany.
- Number of culture flasks/concentration: 2

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

10

Sampling time:

2 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

75

Sampling time:

12 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

89

Sampling time:

28 d

Table 5.2.1/1: Actual concentration of test and reference substance

Flask No.	Abbreviation used in the formula	Concentration of the test substance (mg/l)	Concentration of the reference substance (mg/l)	pH initial	pH final
1	A1	0	100.0	7.5	7.9
2	A2	0	100.0	7.5	7.9
3	B1	0	0	7.5	7.5
4	B2	0	0	7.5	7.4
19	C1	29.9	0	7.5	7.5
20	C2	30.0	0	7.5	7.5

Oxygen uptakes, as read on the Oxitop controller, are corrected to account for the small differences between actual and nominal concentrations of test and reference substances.

Calculated % biodegradation and detailed results are tabulated below.

Table 5.2.1/2: % biodegradation of test substance

	Days		1	2	12	14	21	28	38
O2 uptake of sludge (inoculum blank)	3	B1	-4.2	2.1	14.7	14.7	16.8	16.8	21.0
	4	B2	-4.3	0.0	12.9	15.0	17.1	17.1	23.6
	Mean	B	-4.3	1.1	13.8	14.9	17.0	17.0	22.3
O2 uptake of Test substance + Sludge	19	C1	-8.1	10.1	75.0	79.0	87.2	89.2	95.3
	20	C2	-10.1	8.1	72.8	76.9	83.1	87.1	91.2
O2 uptake of Test substance		C1-B	-3.9	9.1	61.2	64.2	70.2	72.2	73.0
		C2-B	-5.9	7.1	59.0	62.1	66.1	70.1	68.9
% biodegradation of Test substance		D1	-5	11	77	80	88	90	91
		D2	-7	9	74	78	83	88	86
	Mean	D	-6	10	75	79	85	89	89

 

B1, B2, C1, C2, A1, A2, E1: experimental O₂uptake values

B=(B1+B2)/2

D1 =100*(C1-B)/ThOD * (s)

D2 =100*(C2-B)/ThOD * (s)

D=(D1+D2)/2

[S]: initial test substance concentration (mg/l)

ThOD = 2.66 mg O₂/mg

 

Table 5.2.1/3: % biodegradation of reference substance

	Days		5	7	14	21	28	38
O2 uptake of sludge (inoculum blank)	3	B1	8.4	10.5	14.7	16.8	16.8	21.0
	4	B2	8.6	10.7	15.0	17.1	17.1	23.6
	Mean	B	8.5	10.6	14.9	17.0	17.0	22.3
O2 uptake of Test substance + Sludge	19	A1	122.0	135.0	158.0	164.0	169.0	173.0
	20	A2	117.0	132.0	151.0	162.0	166.0	168.0
O2 uptake of Test substance		A1-B	113.5	124.4	143.2	147.1	152.1	150.7
		A2-B	108.5	121.4	136.2	145.1	149.1	145.7
% biodegradation of Test substance		D1	68	75	86	88	91	90
		D2	65	73	82	87	89	87
	Mean	D	67	74	84	88	90	89

 

B1, B2, C1, C2, A1, A2, E1: experimental O₂uptake values

B=(B1+B2)/2

D1 =100*(A1-B)/ThOD * (s)

D2 =100*(A2-B)/ThOD * (s)

D=(D1+D2)/2

[S]: initial reference substance concentration (mg/l)

ThOD = 1.67 mg O₂/mg

 

Degradation of sodium benzoate exceeded 40% after 7 days and 65% after 14 days: the activity of the inoculum was thus verified (validity criterion).

The repeatability validity criterion (not more than 20% difference between replicates) is fulfilled for the flasks containing test substance. Therefore, the test is considered valid.

An optional toxicity control as suggested by OECD guideline 301 F was not performed. The validity of the study is not adversely affected.

A first test performed from March 22, 2013 to April 22, 2013 had to be repeated as the biodegradation rate observed on the two replicate flasks was different by more than 20% at test end (59% and 3%, on day 31, respectively). Only the results of the second, valid test, performed from May 06, 2013 to June 13, 2013 are reported in detail here.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Test item undergoes 89% biodegradation after 28 days in the test conditions. The 10-day window criterion is also fulfilled (10% biodegradation on day 2 and 75% on day 12). Test item did not inhibit the intrinsic respiration of the inoculum at the test concentration and was therefore considered to be non-toxic to the inoculum at the test concentration. Thus, test item should be regarded as readily biodegradable according to this test.

Executive summary:

The Ready Biodegradability of test item was determined by the Manometric Respirometry Test as per OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test); EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test) and EPA OPPTS 835.3210 (Inherent Biodegradability: Modified SCAS Test).

 

Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage (Bois-de-Bay, Satigny, Switzerland).

 

Test substance samples (13.10 mg, corresponding to 30.0 mg/I in 437 ml of test medium) are weighed in small aluminium boats and added directly to the test flasks of the Oxitop. For reference substance samples 43.70 mg (corresponding to 100.0 mg/I in 437 ml of test medium) are weighed in small aluminium boats and added directly to the test flasks of the Oxitop.

Flasks are filled with 432 ml of mineral medium. Samples of test or reference substance are added. Then 5.00 ml of suspended sludge diluted to a concentration of 2.62 g/I dry matter is added. Except when the test substance has an acid or alkaline character, the pH of each flask is not measured but assumed to be the same as the mineral medium, in order not to remove any floating undissolved test substance from the test medium by dipping a glass electrode in it. Neutral test substances, even sodium benzoate, were shown not to affect the pH of the medium by more than 0.1 pH unit. Two sodium hydroxide pellets are placed in the quivers on top of the bottle, and the flasks are closed tightly with the measuring heads. The flasks are allowed to equilibrate to the test temperature. The measurement is started by programming the measuring unit of the Oxitop test flasks, and the test flasks are placed in the temperature-controlled cupboard of the Oxitop system. After temperature equilibration, the controller of the instrument starts the data acquisition (time zero of the experiment).

Everyday the oxygen consumption of each flask is recorded and correct temperature and stirring are checked. At the end of the test period (normally 28 days), the pH of each flask is measured again.

 

Test item undergoes 89% biodegradation after 28 days in the test conditions. The 10-day window criterion is also fulfilled (10% biodegradation on day 2 and 75% on day 12). Test item did not inhibit the intrinsic respiration of the inoculum at the test concentration and was therefore considered to be non-toxic to the inoculum at the test concentration.

Thus, test item should be regarded as readily biodegradable according to this test.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater