7-methyl-3-methyleneocta-1,6-diene

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:

2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Well described GLP study acording to OECD 301D guideline and giving reliable information on myrcene biodegradability.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

ammonium chloride was omitted from the medium to prevent oxygen consumption due to nitrification/ activated sludge instead of effluent/ extract/mixture was used as inoculum

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): wastewater treatment plant Nieuwgraaf in Duiven, The Netherlands
- Pretreatment: the activated sludge was pre-conditionned to reduce the endogeous respiration rates. 400 mg dry weight/L of activated sludge was aerated for one week.

Duration of test (contact time):

28 d

Initial conc.:

2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: per liter of deionized water: 8.5mg KH2PO4, 21.75mg K2HPO4, 33.3mg Na2HPO4.2H2O, 22.5mg MgSO4.7H2O, 27.5mg CaCl2, 0.25mg FECl3.6H2O
- Additional substrate: silica gel
- Test temperature: within the prescribed temperature range of 22 to 24°C
- pH: 6.8 (control, control with silica), 6.9 (test)
- pH adjusted: no
- Continuous darkness: yes

TEST SYSTEM
- Number of culture flasks/concentration: 10 bottles containing only inoculum, 10 bottles containing inoculum and silica gel, 10 bottles containing inoculum and silica gel dosed with test substance, 6 bottles containing sodium acetate and inoculum
- Measuring equipment: an oxygen electrode (WTW TrioXmatic EO 200) and meter (WTW OXI 530) to electrochemically determine the dissolved oxygen concentrations, a Knick 765 calimatic pHmeter to measure pH, a sensor connected to a data logger to measure and record the temperature
- Test performed in closed vessels due to significant volatility of test substance

SAMPLING
- Sampling frequency: weekly
- Sampling method: Two duplicate bottles of all series were withdrawn for analyses of the dissolved oxygen concentration at day 7, 14, 21, and 28.
- Sample storage before analysis: the bottles were closed and incubated in the dark

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: no inhibition of the biodegradation due to the "high" initial concentration of the test substance is expected

Reference substance:

acetic acid, sodium salt

Test performance:

The validity of the test is demonstrated by an endogenous respiration of 1.0 mg/L at day 28. Sodium acetate was degraded 83% of its ThOD after 28 days. The validity of the test is also shown by oxygen concentrations >0.5 mg/L in all bottles during the test period.

Key result

Parameter:

% degradation (O2 consumption)

Value:

76

Sampling time:

28 d

Details on results:

The pass level of 60% was reached after approximately 10 days upon achieving 10% biodegradation. Myrcene therefore fulfilled the 14-day time window (10-day for other OECD 301 tests) criterion for ready biodegradable compounds. The 14-day window is considered acceptable for the Closed Bottle test because the number of bottles to evaluate the 10-day window causes the test to become too unwieldy (OECD, 1992).

Results with reference substance:

See Tables in "any other information on results incl. tables section :
Table 1: Dissolved oxygen concentrations (mg/L) in the closed bottles.
Table 2: Oxygen consumption (mg/L) and the percentages biodegradation of the test substance, Myrcene (BOD/ThOD) and sodium acetate (BOD/ThOD) in the Closed Bottle test.

Table 1: Dissolved oxygen concentrations (mg/L) in the closed bottles.

Time (days)	Oxygen concentration (mg/L)
	Ocs	Ot	Oc	Oa
0	8.6	8.6	8.6	8.6
	8.6	8.6	8.6	8.6
Mean	8.6	8.6	8.6	8.6
7	7.8	4.9	8.0	3.9
	8.0	5.3	7.9	3.9
Mean	7.9	5.1	8.0	3.9
14	7.8	3.5	7.7	3.4
	7.6	3.3	7.8	3.2
Mean	7.7	3.4	7.7	3.3
21	7.7	2.8	7.8
	7.6	2.9	7.6
Mean	7.7	2.9	7.7
28	7.6	2.6	7.5
	7.6	2.6	7.6
Mean	7.6	2.6	7.6

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

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

Oc Mineral nutrient solution with only inoculum.

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

 

Table 2: Oxygen consumption (mg/L) and the percentages biodegradation of the test substance, Myrcene (BOD/ThOD) and sodium acetate (BOD/ThOD) in the Closed Bottle test.

 

Time (days)	Oxygen consumption (mg/L)		Biodegradation (%)
	Test substance	Acetate	Test substance	Acetate
0	0.0	0.0	0	0
7	2.8	4.1	42	76
14	4.3	4.5	65	83
21	4.8		73
28	5.0		76

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Myrcene was readily biodegradable in a study conducted according to guideline OECD 301 D (biodegradation: 76% in 28 days).

Executive summary:

A ready biodegradability study in closed bottles was conducted with substance myrcene according to guideline OECD 301 D.

The test item was introduced in closed bottles with preconditionned activated sludge (origin: wastewater treatment plant Nieuwgraaf in Duiven, NL). The closed bottles were incubated for 28 days at 23°C ± 1°C in the activated sludge and the oxygen consumption during this period was measured.

The BOD values were related to Theorical oxygen demand (ThOD) and percentage biodegradability in water was estimated.

Reference substance was Sodium acetate.

Oxygen consumption after 28 days of incubation was 5 mg O₂/L test substance.

% BOD of ThOD after 28 days of incubation was 76%.

The test substance did not inhibit bacterial respiration at the tested concentration. Abiotic degradation was not recorded.

Therefore, it is considered that the test substance is readily biodegradable according to the criteria of guideline OECD 301D.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2007

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

documentation insufficient for assessment

Remarks:

Study conducted according to OECD Guideline 301 C but with deviations: no detail on material and methods

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Deviations:

yes

Remarks:

no detail on material and methods

Principles of method if other than guideline:

Not applicable

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

Concentration of activated sludge : 30 ppm

Duration of test (contact time):

14 d

Initial conc.:

100 other: ppm

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Parameter:

% degradation (O2 consumption)

Value:

>= 90 - <= 95

Sampling time:

28 d

Details on results:

- Indirect analysis (BOD): 86%
- Direct analysis (TOC): 87%
- Direct analysis (GC): 99%

None

Validity criteria fulfilled:

not specified

Interpretation of results:

readily biodegradable

Conclusions:

Under the test conditions, myrcene was readily biodegradable.

Executive summary:

In a ready biodegradation study performed according to OECD Guideline 301 C, myrcene was tested at concentrations of 100 ppm and the inoculum was activated sludge (30 ppm). The degradation of the test material was assessed by the determination of the oxygen consumption.

At the test concentration of 100 ppm, 86% of degradation (biochemical oxygen demand) was reached in 14 days.

 

Therefore, myrcene was readily biodegradable.

 

Description of key information

Myrcene was found to be readily biodegradable in a GLP study conducted according to the criteria of the OECD 301 D guideline.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

A test was carried out according to OECD 301D Ready biodegradability in closed bottles.

The test substance was incubated for 28 days at 23°C ± 1°C in closed bottles with preconditioned activated sludge and the oxygen consumption during this period was measured. % BOD of ThOD after 28 days of incubation was 76%.

In a ready biodegradation study performed according to OECD Guideline 301 C, myrcene was tested at concentrations of 100 ppm and the inoculum was activated sludge (30 ppm). The degradation of the test material was assessed by the determination of the oxygen consumption.

At a concentration of 100 ppm, 86% of degradation (biochemical oxygen demand) was reached in 14 days.

Therefore the test substance is readily biodegradable according to the criteria of the OECD 301 guideline.