4-isopropyl-1-methylcyclohexene

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

The study was conducted between 30 July 2015 and 25 November 2015.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

4-isopropyl-1-methylcyclohexene

EC Number:

226-841-5

EC Name:

4-isopropyl-1-methylcyclohexene

Cas Number:

5502-88-5

Molecular formula:

C10H18

IUPAC Name:

1-methyl-4-(propan-2-yl)cyclohex-1-ene

impurity 1

Reference substance name:

rel-(1R,4R)-1-isopropyl-4-methylcyclohexane

Cas Number:

1678-82-6

Molecular formula:

C10H20

IUPAC Name:

rel-(1R,4R)-1-isopropyl-4-methylcyclohexane

impurity 2

Reference substance name:

rel-(1S,4S)-1-isopropyl-4-methylcyclohexane

Cas Number:

6069-98-3

Molecular formula:

C10H20

IUPAC Name:

rel-(1S,4S)-1-isopropyl-4-methylcyclohexane

Test material form:

liquid

Specific details on test material used for the study:

Lot No.: VE00370265
Aspect: colourless to pale yellow liquid
Purity: 83.3% (major peak)

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic, non-adapted

Details on inoculum:

Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic 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.

Duration of test (contact time):

62 d

Initial test substance concentration

Initial conc.:

30 mg/L

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

% Degradation 1

Key result

Parameter:

% degradation (O2 consumption)

Value:

35

Sampling time:

28 d

Remarks on result:

other: test concentration of 30 mg/L

% Degradation 2

Parameter:

% degradation (O2 consumption)

Value:

54

Sampling time:

62 d

Remarks on result:

other: test concentration of 30 mg/L

Any other information on results incl. tables

RESULTS

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.

Calculated % biodegradation curves and detailed in the table below:

O₂uptake (mg O₂/L, adjusted to nominal concentrations):

	Days:		7	14	21	28	35	42	62
O2 uptake of sludge (inoculum blank)	3	B1	17.0	21.3	23.4	25.6	25.6	25.6	27.7
	4	B2	16.9	21.2	21.2	25.4	27.5	27.5	27.5
	mean	B	17.0	21.3	22.3	25.5	26.6	26.6	27.6
O2 uptake of Test Subst. + sludge	5	C1	27.5	46.5	54.9	63.5	69.8	76.2	84.6
	6	C2	27.4	40.2	48.6	57.1	63.4	69.7	80.4
O2 uptake of Test Substance		C1-B	10.6	25.3	32.6	38.0	43.2	49.6	57.0
		C2-B	10.5	18.9	26.3	31.6	36.9	43.2	52.8
% biodegradation of test substance		D1	10	25	32	38	43	49	57
		D2	10	19	26	31	37	43	52
	mean	D	10	22	29	35	40	46	54

Calculations:

B1, B2, C1, C2, A1, A2, E1: experimental O₂uptake values

B = (B1 + B2)I2

D1 = 100 * (C1- B) /ThOD * [S]

D2 = 100 * (C2- B) /ThOD * [S]

D = (D1 + D2)/2

[S] : Initial test substance concentration (mg/L)

 

Degradation of sodium benzoate exceeded 40% after 7 days and 65% after 14 days: the activity of the inoculum was thus verified (validity criterion).

The repeatability validity criterion (not more than 20% difference between replicates) is fulfilled for the flasks containing test substance. Therefore, the test is considered valid.

 

COMMENTS AND CONCLUSIONS

The Ready Biodegradability of Menthene, -1, Para was determined by the Monometric Respirometry Test.

Menthene, -1, Para undergoes 35% biodegradation after 28 days (54% after 62 days) in the test conditions.

Menthene, -1, Para 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.

Thus, Menthene, -1, Para should be regarded as not readily biodegradable according to this test.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

Menthene, -1, Para undergoes 35% biodegradation after 28 days (54% after 62 days) in the test conditions.
Menthene, -1, Para did not significantly 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.
Thus, Menthene, -1, Para should be regarded as not readily biodegradable according to this test.

Executive summary:

The Ready Biodegradability of Menthene, -1, Para was determined by the Monometric Respirometry Test according to OECD Guideline for the Testing of Chemicals No. 301F, Paris, 1992.

Menthene, -1, Para undergoes 35% biodegradation after 28 days (54% after 62 days) in the test conditions.

Menthene, -1, Para did not significantly 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.

Thus, Menthene, -1, Para should be regarded as not readily biodegradable according to this test.