Myrac Aldehyde

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:

1 December 2009 to 30 December 2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

although minor deviations from guideline are reported (see 'Any other information on materials and methods'), these are not considered to have affected the overall reliability of the test.

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Version / remarks:

Version 1992

Deviations:

yes

Remarks:

see 'Any other information on materials and methods incl. tables'.

Qualifier:

according to guideline

Guideline:

EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)

Version / remarks:

Version 1992

Deviations:

yes

Remarks:

see 'Any other information on materials and methods incl. tables'.

Qualifier:

according to guideline

Guideline:

ISO 10707 Water quality - Evaluation in an aqueous medium of the "ultimate" aerobic biodegradability of organic compounds - Method by analysis of biochemical oxygen demand (closed bottle test)

Version / remarks:

Version 1994

Deviations:

yes

Remarks:

see 'Any other information on materials and methods incl. tables'.

GLP compliance:

yes (incl. QA statement)

Remarks:

Food and Consumer Product Safety Authority (VWA). Prinses Beatrixlaan 2, 2595 AL Den Haag. Postbus 19506, 2500 CM Den Haag, The Netherlands (d.d. 19 March 2008).

Specific details on test material used for the study:

- Solubility in water: 49 mg/L
- Test material storage: At ambient temperature in the dark

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source: Secondary activated sludge (25-11-2009) was obtained from the wastewater treatment plant Nieuwgraaf in Duiven, The Netherlands. This plant is an activated sludge plant treating predominantly domestic wastewater.
- Pre-conditioning: The activated sludge was pre-conditioned to reduce the endogenous respiration rates. To this end, 400 mg Dry Weight (DW)/L of activated sludge was aerated for one week. The sludge was diluted in the BOD bottles.

Duration of test (contact time):

28 d

Initial conc.:

ca. 2 mg/L

Based on:

test mat.

Initial conc.:

ca. 5.8 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: The nutrient medium of the Closed Bottle test contained per liter of deionized water: 8.5 mg KH2P04, 21.75 mg K2HP04, 33.3 mg Na2HP04·2H2O, 22.5 mg MgS04·7H2O, 27.5 mg CaCl2, 0.25 mg FeCl3·6H2O. Ammonium chloride was omitted from the medium to prevent nitrification.
- Test concentrations: Administration of myrac aldehyde was accomplished by dosing 0.03 g of myrac aldehyde on 10 g of silica gel in a 50-ml serum flask. Only part of the top layer of the silica gel was brought into contact with the fragrance substance. The serum flask was closed with a screw top with alumiminium foil and the content was mixed vigorously. Subsequently 0.2 g of silica gel dosed with myrac aldehyde was added to the test bottles. The resulting concentration of test substance in the bottles is ~2.0 mg/L. Next the bottles were filled with nutrient medium with inoculum and closed. Each of the prepared solutions was dispensed into the respective group of BOD bottles so that all bottles were completely filled without air bubbles.
- Reference substance: Sodium acetate was added to the bottles at a concentration of 6.7 mg/L (5.36 mg/L based on ThOD). For preparations of reference solutions a stock solution of 1.0 g/L was used.
- Test bottles: The test was performed in 0.30 L BOD (biological oxygen demand) bottles with glass stoppers. Use was made of 10 bottles containing only inoculum, 10 bottles containing inoculum and silica gel, 10 bottles containing inoculum and silica gel dosed with test substance test substance and silica gel, and 6 bottles containing sodium acetate and inoculum.
- Toxicity control: Inhibition of the degradation of a well-degradable compound, e.g. sodium acetate by the test substance in the Closed Bottle test was not determined because possible toxicity of myrac aldehyde to microorganisms degrading acetate is not relevant. Inhibition of the endogenous respiration of the inoculum by the test substance was not detected. Therefore, no inhibition of the biodegradation due to the "high" initial concentration of the test substance is expected.
- Sampling: The zero time bottles were immediately analyzed for dissolved oxygen using an oxygen electrode. The remaining bottles were closed and incubated in the dark. Two duplicate bottles of all series were withdrawn for analyses of the dissolved oxygen concentration at day 7, 14, 21, and 28.
- Temperature: The temperature was measured and recorded with a sensor connected to a data logger. Temperatures were within the prescribed temperature range of 22 to 24°C.
- pH: The pH was measured using a Knick 765 calimatic pH meter (Elektronische Messgerate GmbH, Berlin, Germany). The pH of the media was 7.0 at the start of the test. The pH of the medium at day 28 was 6.9.

Reference substance:

acetic acid, sodium salt

Remarks:

6.7 mg/L based on test mat., 5.36 mg/L based on ThOD

Key result

Parameter:

% degradation (O2 consumption)

Value:

71

Sampling time:

28 d

Details on results:

The pass level of 60% was not reached within 10 days upon achieving 10% biodegradation. Myrac aldehyde therefore only fulfilled one criterion for ready biodegradable compounds i.e. a biodegradation percentage in excess of 60 within 28 days. The reason for failing the 10-day window is the composition of myrac aldehyde. Myrac aldehyde is a mixture of two isomers 3-and 4-( 4-methyl-3-penten-1-yl)-3-cyclohexene-1-carbaldehyde. One isomer is present at ~70% and the other at ~30%. The degradation curve is therefore the sum of two growth curves. The 10-day time window criterion was developed on the assumption that a single compound is degraded according to a "standard" growth curve in ready biodegradability tests. The time-window should therefore be ignored as a pass fail criterion for myrac aldehyde. Myrac aldehyde is therefore classified as readily biodegradable only based on the biodegradation percentage of 71 % at day 28.

Table: Dissolved oxvqen concentrations (mg/L) in the closed bottles

Time (days)	Oxygen concentration (mg/L)
	Ocs	Ot	Oc	Oa
0	8.7	8.7	8.7	8.7
	8.7	8.7	8.7	8.7
Mean (M)	8.7	8.7	8.7	8.7
7	7.8	7.5	7.8	3.6
	7.9	7.6	7.8	3.6
Mean (M)	7.9	7.6	7.8	3.6
14	7.4	4.5	7.4	2.9
	7.5	4.2	7.4	2.8
Mean (M)	7.5	4.4	7.4	2.9
21	7.4	4.1	7.3	-
	7.3	4.2	7.3	-
Mean (M)	7.4	4.2	7.3	-
28	7.4	3.3	7.3	-
	7.4	2.9	7.3	-
Mean (M)	7.4	3.1	7.3	-

Ocs: Mineral nutrient solution without test material but with inoculum and silica gel.

Ot: Mineral nutrient solution with test material (ca. 2.0 mg/L), silica gel, and inoculum.

Oc: Mineral nutrient solution with only inoculum.

Oa: Mineral nutrient solution with sodium acetate (ca. 6.7 mg/L) and with inoculum.

 

Table: Oxygen consumption (mg/L) and the percentages biodegradation of the test substance, myrac aldehyde (BOD/ThOD) and sodium acetate (BOD/ThOD) in the Closed Bottle test.

Time (days)	Oxyqen consumption (mq/L)		Biodegradation (%)
	Test substance	Acetate	Test substance	Acetate
0	0.0	0.0	0	0
7	0.3	4.2	5	78
14	3.0	4.5	52	83
21	3.1	-	53	-
28	4.1	-	71	-

 

Validity criteria fulfilled:

yes

Remarks:

see 'Any other information on materials and methods incl. tables'.

Interpretation of results:

readily biodegradable

Conclusions:

The substance is readily biodegradable under the conditions of the test.

Executive summary:

The biodegradation potential of 3-CYCLOHEXENE-1-CARBOXALDEHYDE MULTICONSTITUENT was examined in a study according to OECD TG 301D (Closed Bottle test) and in compliance with GLP criteria.

In this study 2 mg/L test substance (ca. 5.8 mg/L based on ThOD) was inoculated for 28 days under aerobic conditions and in the dark with secondary activated sludge obtained from a municipal wastewater treatment plant treating predominantly domestic wastewater. Two duplicate bottles of all series were withdrawn for analyses of the dissolved oxygen concentration at day 0 and after 7, 14, 21, and 28 exposure and the cumulative percentages biodegradation calculated from the oxygen depletion ratio BOD/ThOD. Minor deviations from the guideline included omitting ammonium chloride from the medium to prevent oxygen consumption due to nitrification and use of secondary activated sludge as inoculum instead of an effluent/extract/mixture. Also, the pH was 7.0 at the start of the test instead of the recommended pH of 7.4 ± 0.2. None of these deviations are however considered to have affected the overall reliability or outcome of the test. All validity criteria were met.  

After the 28-day incubation period the substance was biodegraded 71%. The 10-day window criterion was not met. The reason for failing the 10-day window is that the test substance is a mixture of two isomers present at 70% and 30%, respectively. The degradation curve is therefore the sum of two growth curves whereas the 10-day time window criterion was developed on the assumption that a single compound is degraded according to a ‘standard’ growth curve in ready biodegradability tests. The time-window may therefore be ignored as pass/fail criterion and the substance should be classified as readily biodegradable based on the biodegradation percentage of 71% at day 28 alone.

Description of key information

The biodegradation potential of 3 -CYCLOHEXENE-1 -CARBOXALDEHYDE MULTICONSTITUENT was examined in a study according to OECD TG 301D (Closed Bottle test) and in compliance with GLP criteria.

In this study 2 mg/L test substance (ca. 5.8 mg/L based on ThOD) was inoculated for 28 days under aerobic conditions and in the dark with secondary activated sludge obtained from a municipal wastewater treatment plant treating predominantly domestic wastewater. Two duplicate bottles of all series were withdrawn for analyses of the dissolved oxygen concentration at day 0 and after 7, 14, 21, and 28 exposure and the cumulative percentages biodegradation calculated from the oxygen depletion ratio BOD/ThOD. Minor deviations from the guideline included omitting ammonium chloride from the medium to prevent oxygen consumption due to nitrification and use of secondary activated sludge as inoculum instead of an effluent/extract/mixture. Also, the pH was 7.0 at the start of the test instead of the recommended pH of 7.4 ± 0.2. None of these deviations are however considered to have affected the overall reliability or outcome of the test. All validity criteria were met.  

After the 28-day incubation period the substance was biodegraded 71%. The 10-day window criterion was not met. The reason for failing the 10-day window is that the test substance is a mixture of two isomers present at 70% and 30%, respectively. The degradation curve is therefore the sum of two growth curves whereas the 10-day time window criterion was developed on the assumption that a single compound is degraded according to a ‘standard’ growth curve in ready biodegradability tests. The time-window may therefore be ignored as pass/fail criterion and Myrac aldehyde be classified as readily biodegradable based on the biodegradation percentage of 71% at day 28 alone.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater