4-(1-methoxy-1-methylethyl)-1-methylcyclohexene

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:

From 18 June 2010 to 19 July 2010.

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)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

- Substance name: Orange Flower Ether
- CAS number: 14576-08-0

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

Fresh activated sludge from a biological waste water treatment plant treating predominantly dornestic sewage (Bois-de-Bay, Satigny, Switzerland) was used. 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. The dry weight of suspended solids is determined by taking two 50 mL samples of the homogenised sludge, evaporating water on a steam bath, drying in an oven at 105 - 110 °C for two hours and weighing the residue. The dry weight of suspended solid was 5.23 g/L and diluted to 1.0 g/L for dosage.

Duration of test (contact time):

31 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

MINERAL MEDIUM
Prepared by mixing 50 mL of sofution 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.
- Solution A: 8.5 g/L KH2PO4, 21.75 g/L K2HPO4, 33.4 g/L Na2HPO4·2H20 and 0.5 g/L NH4Cl.
- Solution B: 27.5 g/L CaCl2
- Solution C: 22.5 g/L MgSO4·7H2O
- Solution D: 0.25 g/L FeCl3·6H2O and one drop of HCl per litre.

PREPARATION OF TEST SOLUTIONS
To obtain a concentration of 30 mg/L (dry weight) in 100/101 mL of test medium, 3.00 mL of diluted sludge is needed (inoculum). To obtain a concentration of 30 mg/L (dry weight) in 200 mL of test medium, 6.00 mL of diluted sludge is needed (inoculum).

PREPARATION OF TEST FLASKS
Test substance samples (10.0 mg, corresponding to 100 mg/L in 100 mL of test medium) are weighed in small aluminium boats and added directly to the test flasks of the Oxitop, whereas reference the substance (sodium benzoate) is added as 1.00 mL of a 10.0 g/L solution in mineral medium, to give a total volume of 101 mL. Flasks are filled with 97 mL of mineral medium (flasks containing sludge only: 194 mL). Samples of test or reference substance are added. Then suspended sludge diluted to a concentration of 1.0 g/L 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). The initial pH is set at 7.6. The test temperature is 22°C.

PERFORMANCE OF THE TEST
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.

APPARATUS
The respirometer used during this study is an Oxitop Control System, made by Wissenschaftlich-Technische Werkstätten (WTW), Weilheim, Germany.

Reference substance:

benzoic acid, sodium salt

Remarks:

100 mg/L

Test performance:

- Degradation of sodium benzoate exceeded 40 % after 7 days and 65 % after 14 days: the activity of the inoculum was thus verified (validity criterion).
- Not more than 20% difference between replicates (validity criterion ).
- Orange Flower Ether 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.

Key result

Parameter:

% degradation (O2 consumption)

Value:

76

Sampling time:

28 d

Remarks on result:

other: The substance is considered readily biodegradable because > 70% is degraded within 28-days, despite the 10-day window criterion is not fulfilled (13 % biodegradation on day 9 and 59 % on day 19).

Results with reference substance:

40 % after 7 days and 65 % after 14 days

Biodegradability

Test Flask	#	Days
		8	9	14	19	21	28	31
O2 uptake of sludge (inoculum blank)	1a	22.7	22.7	28.9	33.0	35.1	39.2	41.3
	2a	22.7	24.8	31.0	37.1	37.1	43.3	47.5
	Mean	22.7	23.8	30.0	35.1	36.1	41.3	44.4
O2 uptake of test substance + sludge	17a	37.7	53.9	150.9	198.8	215.8	252.8	263.8
	18a	48.5	70.1	167.1	221.2	237.2	280.2	286.2
O2 uptake of test substance		15.0	30.1	120.9	163.8	179.7	211.5	219.4
		25.8	46.4	137.2	186.1	201.1	239.0	241.8
% biodegradation of test substance		5	10	41	56	61	72	74
		9	16	47	63	68	81	82
	mean	7	13	44	59	65	76	78

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.

Validity criteria fulfilled:

yes

Remarks:

See 'Test performance'.

Interpretation of results:

readily biodegradable

Conclusions:

The substance is readily biodegradable.

Executive summary:

The biodegradation potential of the substance in water was determined in a screening study according to OECD TG 301F (Manometric Respirometry) and in compliance with GLP criteria (Givaudan, 2010). In this study 100 mg/L test substance was inoculated with activated sludge from a municipal wastewater treatment plant for 31 days under aerobic conditions. During the incubation period the biological oxygen demand (BOD) was measured and biodegradation expressed as percentage of the theoretical uptake (ThOD). Orange Flower Ether 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. The substance was biodegraded 76 % after 28 days in the test conditions. The 10-day window criterion was not fulfilled (13 % biodegradation on day 9 and 59 % on day 19). In view of the substance being degraded for > 70% (76%) and it contains more than one constituents the10-day window does not need to be met (CLP 4.1.2.9.5 consolidated version of Feb 2016: 4.1.2.9.5 at ii) c; ii), respectively). Based on these findings the substance is assessed as readily biodegradable.

Description of key information

The biodegradation potential of the substance in water was determined in a screening study according to OECD TG 301F. Under the conditions of the test the substance was readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

The biodegradation potential of the substance in water was determined in a screening study according to OECD TG 301F (Manometric Respirometry) and in compliance with GLP criteria (Givaudan, 2010). In this study 100 mg/L test substance was inoculated with activated sludge from a municipal wastewater treatment plant for 31 days under aerobic conditions. During the incubation period the biological oxygen demand (BOD) was measured and biodegradation expressed as percentage of the theoretical uptake (ThOD). Orange Flower Ether 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. The substance was biodegraded 76 % after 28 days in the test conditions. The 10-day window criterion was not fulfilled (13 % biodegradation on day 9 and 59 % on day 19). In view of the substance being degraded for > 70% (76%) and it contains more than one constituents the10-day window does not need to be met (CLP 4.1.2.9.5 consolidated version of Feb 2016: 4.1.2.9.5 at ii) c; ii), respectively). Based on these findings the substance is assessed as readily biodegradable.