Myrcenyl acetate

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:

1999-11-18 to 1999-12-17

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

GLP compliance:

yes

Oxygen conditions:

not specified

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage (City of Geneva, Aire) was used.
- Preparation of inoculum for exposure: 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.
- Determination of the dry weight of suspended solids: 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 oC for two hours and weighing the residue.
- Dry weight of suspended solids: 3.289 g/L

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Water used during this study is deionised water containing less than 10 mg/L dissolved organic carbon.
- Composition of medium: Stock solutions of mineral components (solution A, B, C, D) were prepared according to the guideline. 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: 22 oC
- pH: 7.4 (at initiation)
- Activated sludge: to obtain a concentration of 30 mg/L (dry weight) in a 250 mL flask, 2.28 mL of sludge (dry weight of suspended solids: 3.289 g/L) is needed (inoculum).

TEST SYSTEM
- Culturing apparatus: Respirometer, SAPROMAT D12, made by J. M. VOITH GmbH, Heidenheim, Germany.
- Number of culture flasks/concentration: 2/test suspension, 2/procedure control, 2/inoculum blank, 2/toxicity control
- Measuring equipment: SAPROMAT meter
- Details of trap for CO2 if used: about 2 g soda lime is placed in an attachment of the stopper of 250-mL flasks.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: Yes, the toxicity of the test chemical for the inoculum is checked. Therefore, a pair of flasks of the volumetric respirometer are filled with mineral medium + test chemical (100 mg/L) + reference substance (100 mg/L) + inoculum and their respirations are recorded as for the other flasks. If they are lower than those of the flasks containing mineral medium + referenc substance (100 mg/L) + incoculum, the test chemical can be assumed to be inhibitory to the inoculum used.

RESULTS
Oxygen uptakes, as read on the SAPROMAT meters, are corrected:
- by deducting the basic oxygen uptake of sludge
- proportionally to account for the small differences between actual and nominal concentrations of test and reference substances
Means of identical flasks were used to obtain the different results and curves.

Reference substance:

other: Sodium Benzoate (Purity: min. 99.0%)

Remarks:

Test concentration: 100 mg/L

Test performance:

Final pH values are all surprisingly high (7.93 -9.36). This suggests more a misfunctioning of the pH meter than an unusual behaviour of the test solutions. The test results were not affected.

Key result

Parameter:

% degradation (O2 consumption)

Value:

79

Sampling time:

28 d

Remarks on result:

other: Biodegradation starts on day 3 and reaches 61% at the end of the 10-day window (days 3 to 13).

Details on results:

The test substance undergoes 79% biodegradation after 28 days in the test conditions. Biodegradation starts on day 3 and reaches 61% at the end of the 10-day window (days 3 to 13), just meeting the 10-day window. Thus the test substance should be regarded as readily biodegradable according to this test.

Results with reference substance:

Degradation of sodium benzoate exceeds 40% after 7 days and 65% after 14 days, the activity of the inoculum is thus verified and the test is considered as valid.

Biological Oxygen Demand (BOD, mg O2/L, adjusted to nominal concentrations):

		Days:	3	7	13	14	21	28
BOD Sludge	1rst flask	B1	6.0	16.0	16.0	17.0	19.0	21.0
	2nd flask	B2	6.0	16.0	16.0	18.0	21.0	21.0
	mean	B	6.0	16.0	16.0	17.5	20.0	21.0
BOD Test substance	1rst flask	C1	63.2	129.4	180.8	182.8	207.7	240.1
	2nd flask	C2	59.9	116.2	168.2	174.1	189.6	214.6
	1rst fl. Corr.	C1-B	57.2	113.4	164.8	165.3	187.7	219.1
	2nd fl. Corr.	C2-B	53.9	100.2	152.2	156.6	169.6	193.6
% Degr.	1rst flask	D1	22	43	63	63	72	84
	2nd flask	D2	21	38	58	60	65	74
	mean	D	21	41	61	62	68	79

The curves obtained with the reference substance alone and with the test substance + reference substance show no toxic effect of the test substance to the micro-organisms at the test concentration.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The substance is biodegraded by 79% after 28 days in the manometric respirometry test (OECD TG 301F). Biodegradation starts on day 3 and reaches 61% at the end of the 10-day window (days 3 to 13), just meeting the 10-day window criteria. Thus the substance should be classified as readily biodegradable according to this test.

Executive summary:

Ready biodegradability of the test substance is tested in the Manometric Respirometry Test, according to OECD 301F and in accordance with GLP. Fresh activated sludge form a biological waste water treatment plant treating predominantly domestic sewage (City of Geneva, Aïre) was used. Test substance was tested at 100 mg/L in 250 mL test flasks of the SAPROMAT respirometer, filled with 250 mL of mineral medium. A volume of suspended sludge is added, 2.28 mL sludge (dry weight of suspended solids is 3.289 g/L) is needed, corresponding to a concentration of 30 mg/L (dry weight). About 2 g of soda lime is placed in an attachment of the stopper, the flasks are closed and placed in the water bath. The test substance undergoes 79% biodegradation after 28 days in the test conditions. Biodegradation starts on day 3 and reaches 61% at the end of the 10-day window, just meeting the 10-day window criteria. Thus the test substance should be classified as readily biodegradable according to this test. Degradation of reference substance, Sodium Benzoate, exceeds 40% after 7 days and 65% after 14 days: the activity of the inoculum is thus verified and the test is considered as valid. No toxic effect of the test substance to the micro-organisms was observed at test concentration.

Description of key information

Ready biodegradability of the test substance is tested in the Manometric Respirometry Test, according to OECD 301F and in accordance with GLP. Fresh activated sludge form a biological waste water treatment plant treating predominantly domestic sewage (City of Geneva, Aïre) was used. Test substance was tested at 100 mg/L in 250 mL test flasks of the SAPROMAT respirometer, filled with 250 mL of mineral medium. A volume of suspended sludge is added, 2.28 mL sludge (dry weight of suspended solids is 3.289 g/L) is needed, corresponding to a concentration of 30 mg/L (dry weight). About 2 g of soda lime is placed in an attachment of the stopper, the flasks are closed and placed in the water bath. The test substance undergoes 79% biodegradation after 28 days in the test conditions. Biodegradation starts on day 3 and reaches 61% at the end of the 10-day window, just meeting the 10-day window criteria. Thus the test substance should be classified as readily biodegradable according to this test. Degradation of reference substance, Sodium Benzoate, exceeds 40% after 7 days and 65% after 14 days: the activity of the inoculum is thus verified and the test is considered as valid. No toxic effect of the test substance to the micro-organisms was observed at test concentration.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable