[3R-(3α,3aβ,6α,7β,8aα)]-octahydro-6-methoxy-3,6,8,8-tetramethyl-1H-3a,7-methanoazulene

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:

to be filled

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: ISO 10707:1994. 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)

Deviations:

no

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

other: 1. Secondary activated sludge, domestic, non-adapted; 2. river water

Details on inoculum:

ACTIVATED SLUDGE
Secondary activated sludge was obtained from the wastewater treatment plant Nieuwgraaf in Duiven, The Netherlands. This plant is an activated sludge plant treating predominantly domestic wastewater. The activated sludge was preconditioned 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 (van Ginkel and Stroo, 1992).

RIVER WATER
River water was sampled from the Rhine near Heveadorp, The Netherlands. The nearest plant (Arnhem-Zuid) treating domestic wastewater biologically was 3 km upstream. The river water was aerated for 7 days before use to reduce the endogenous respiration. River water without particles was used as inoculum. The particles were removed by sedimentation.

Duration of test (contact time):

56 d

Initial conc.:

2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST BOTTLES
The test was performed in 0.3 L BOD (biological oxygen demand) bottles with glass stoppers.

STOCK SOLUTION
Administration of Cedryl Methyl Ether was accomplished by dosing 0.03 g of Cedryl Methyl Ether 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 test 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 Cedryl Methyl Ether was added to the test bottles. The resulting concentration of test substance in the bottles was 2.0 mg/L. Next the bottles were filled with nutrient medium with inoculum or river water and closed.

TEST PROCEDURES
Use was made of 3 bottles containing inoculum and silica gel, and 3 bottles containing inoculum and silica gel dosed with test substance. The concentration of the test substance in the bottles was 2.0 mg/L. Each of the prepared solutions was dispensed into the respective group of BOD bottles so that all bottles were completely filled without air bubbles. The bottles were immediately analyzed for dissolved oxygen using an oxygen electrode. The bottles with magnetic stirrer bars were subsequently closed. These bottles were incubated at 23±1°C in the dark. Oxygen concentrations at days 7, 14, 21, 28, 42 and 56 were measured using a special funnel. This funnel fitted exactly in the BOD bottle. Subsequently, the oxygen electrode was inserted in the BOD bottle to measure the oxygen concentration. The medium dissipated by the electrode was collected in the funnel. After withdrawal of the oxygen electrode the medium collected flowed back into the BOD bottle, followed by removal of the funnel and closing of the BOD bottle (van Ginkel and Stroo 1992).

TEST CONDITIONS
The pH of the media with activated was 7.0 at the start of the test. The pH of the medium at day 28 was 7.0 (control) and 7.1 (test). The pH of the river water with and without test substance at start and end of the test ranged from 7.8 to 8.6. Temperatures were within the prescribed temperature range of 22 to 24°C.

Reference substance:

acetic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

60

Sampling time:

28 d

Remarks on result:

other: when inoculated with river water

Key result

Parameter:

% degradation (O2 consumption)

Value:

53

Sampling time:

28 d

Remarks on result:

other: when inoculated with activated sludge

Details on results:

Using active sludge as inoculums Cedryl Methyl Ether was biodegraded 53 and 61% at day 28 and 56, respectively. The biodegradability of Cedryl Methyl Ether was slightly better with river water. With river water 60% was achieved at day 28. This biodegradation percentage at day 28 allows classification as readily biodegradable. The 14-day time window should not be applied because this substance probably contains different stereoisomers. The test result clearly demonstrates that Cedryl Methyl Ether is not persistent.

Table: Percentages biodegradation of Cedryl Methyl Ether (BOD/ThOD) in the Closed Bottle test.

Time (days)	Biodegradation (%)
	Activated sludge	River water
0	-	-
7	16	-2 (toxic)
14	34	38
21	48	49
28	53	60
42	58	66
56	61	-

Validity criteria fulfilled:

yes

Remarks:

See 'Any other information on materials and methods incl. tables',

Interpretation of results:

readily biodegradable

Conclusions:

The substance showed 60% biodegradation river water in an OECD TG 301D test.

Executive summary:

The ready biodegradability of Cedramber was investigated in a study conducted in accordance with OECD TG 301D (Closed Bottle Test). The concentration tested was 2 mg/l test substance. The biodegradability of the substance was with river water 60% at day 28. This biodegradation percentage at day 28 allows classification as readily biodegradable. The 14 -day time window should not be applied because this substance contains many small impurities. A slight inhibition of the endogenous respiration of the microorganisms present in river water at day 7 by the test substance was detected.

Description of key information

The ready biodegradability of Cedramber was investigated in a study conducted in accordance with OECD TG 301D (Closed Bottle Test). The concentration tested was 2 mg/l test substance. The biodegradability of the substance was with river water 60% at day 28. This biodegradation percentage at day 28 allows classification as readily biodegradable. The 14 -day time window should not be applied because this substance contains many small impurities. A slight inhibition of the endogenous respiration of the microorganisms present in river water at day 7 by the test substance was detected.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable