1,3,3-trimethyl-N-(2-methylpropylidene)-5-[(2-methylpropylidene)amino]cyclohexanemethylamine

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:

2011-05-19 to 2011-06-17

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): A fresh sample of activated sludge from the aeration basin of a municipal sewage treatment plant (Moers, Germany) was collected and aerated until usage.
- Storage condition/length: The inoculum was not fed during the aeration period. The duration of the aeration period was 1 day.
- Preparation of inoculum for exposure: After determination of the suspended solids (dry weight) a sample containing approx.
1875 mg suspended solids was filtered by means of a water jet pump through a filter paper (Whatman GmbH, black ribbon 589(1)). The sludge was washed twice with mineral medium. Afterwards, it was suspended in 250 mL mineral medium and stirred until it was homogeneous.
- Concentration of sludge: 4 mL of this suspension were used to inoculate 1 litre of mineral medium. This amount of inoculum corresponded to 30 mg/L suspended solids.

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
- Composition of medium: mineral medium according to OECD 301
- Test temperature: 22 ± 1 °C
- pH: 7.69 - 8.41
- pH adjusted: no
- Suspended solids concentration: 30 mg/L

TEST SYSTEM
- Culturing apparatus: Sensomat system (Liebherr, Aqualytic, Langen)
- Number of culture flasks/concentration: 3
- Measuring equipment: Sensomat system (Liebherr, Aqualytic, Langen)
- Details of trap for CO2 and volatile organics if used: Before test vessels were closed a CO2 trap consisting of a sodium hydroxide pellet was assembled in the vessel’s head space.

SAMPLING
- Sampling frequency: 360 times during the 28 day experimental period
- Sampling method: measurement of pressure decrease

CONTROL AND BLANK SYSTEM
- Inoculum blank: 3 vessels
- Abiotic sterile control: 2 vessels
- Toxicity control: 2 vessels
- Other: 2 vessels with reference substance, 3 vessels with test substance

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

34

Sampling time:

28 d

Details on results:

At the end of the test period a biodegradation rate of 34 % of the ThODNH4 was measured for the test substance.
Because the biodegradation rate was < 60 % of the ThODNH4 after 28 days,
the test substance cannot be considered to be readily biodegradable under test conditions.
The test substance showed no toxicity towards microorganisms of the activated sludge, because 54 % degradation was recorded within 14 days in the toxicity control preparations containing both the test substance and the positive control substance in the same concentrations.

Results with reference substance:

As reference substance (procedure control) sodium benzoate in a concentration of 100 mg/L was used. After 14 days the reference substance was sufficiently degraded to 88 % of the ThODNH4, thus confirming the suitability of the used activated sludge inoculum and fulfilling the validity criteria mentioned in the relevant test guideline. The reference substance was degraded to 91 % of the ThODNH4 after 28 days.

Oxygen consumption and degradation rates

	oxygen consumption [mg/L]					degradation rates [%]
ThODNH4		287.3	166.7	287.3	454
time (days)	mean value blank control	mean value 100 mg/L abiotic control	mean value 100 mg/L sodium benzoate	mean value 100 mg/L test substance	mean value 100 mg/L * toxicity control	100 mg/L abiotic control	100 mg/L sodium benzoate	100 mg/L test substance	100 mg/L * toxicity control
0	0.0	0.0	0.0	0.0	0.0	0	0	0	0
1	0.1	-3.1	42.9	15.0	45.3	-1	26	5	10
2	2.1	-2.0	70.4	46.4	80.8	-1	41	15	17
3	3.7	-2.0	111.0	64.8	110.0	-1	64	21	23
4	4.9	-2.0	124.0	75.0	163.0	-1	71	24	35
5	6.1	-2.0	133.0	81.9	181.0	-1	76	26	39
6	7.1	-2.0	138.5	88.7	198.5	-1	79	28	42
7	8.0	-2.0	143.0	94.8	218.5	-1	81	30	46
8	8.9	-2.0	146.0	98.8	231.0	-1	82	31	49
9	9.7	-2.0	148.0	102.7	239.0	-1	83	32	50
10	10.7	-2.0	151.5	105.7	245.5	-1	84	33	52
11	11.3	-2.0	154.0	108.0	252.0	-1	86	34	53
12	12.3	-2.0	157.0	110.0	255.5	-1	87	34	54
13	12.8	-2.0	158.0	110.7	257.0	-1	87	34	54
14	13.6	-2.0	159.5	112.0	258.5	-1	88	34	54
15	14.0	-3.1	162.0	112.3	260.5	-1	89	34	54
16	14.7	-3.1	163.0	113.0	260.5	-1	89	34	54
17	15.2	-2.0	164.0	113.7	260.5	-1	89	34	54
18	15.6	-3.1	165.0	113.0	263.5	-1	90	34	55
19	16.4	-2.0	165.5	115.0	262.0	-1	89	34	54
20	16.5	-1.0	166.5	115.0	263.5	0	90	34	54
21	16.8	-2.0	167.5	115.0	263.5	-1	90	34	54
22	17.3	-2.0	168.5	115.7	265.0	-1	91	34	55
23	17.6	-1.0	169.0	116.3	265.0	0	91	34	54
24	17.9	-1.0	169.5	115.7	265.0	0	91	34	54
25	18.3	-1.0	170.0	117.0	265.0	0	91	34	54
26	18.3	0.0	170.5	116.3	265.0	0	91	34	54
27	18.7	1.1	171.0	117.7	265.0	0	91	34	54
28	18.8	2.1	171.0	117.7	266.5	1	91	34	55

* each with test substance and reference substance

Validity criteria fulfilled:

yes

Interpretation of results:

other: not readily biodegradable, but moderate biodegradation was observed

Conclusions:

Because the biodegradation rate was < 60 % of the ThODNH4 after 28 days, the test substance cannot be considered to be readily biodegradable under test conditions. However, moderate biodegradation was observed (34% within 28 days)

Executive summary:

The test substance 1,3,3-trimethyl-N-(2-methylpropylidene)-5-[(2-methylpropylidene)amino]cyclohexanemethylamine was tested in a manometric respirometry test according to the OECD Guideline for Testing of Chemicals, No. 301 F for 28 days to determine whether the test substance is readily biodegradable. At the end of the test period a biodegradation rate of 34 % of the ThOD_NH4was measured. Because the biodegradation rate was < 60 % of the ThOD_NH4 after 28 days, the test substance cannot be considered to be readily biodegradable under test conditions. As reference substance (procedure control) sodium benzoate in a concentration of 100 mg/L was used. After 14 days the reference substance was sufficiently degraded to 88 % of the ThOD_NH4, thus confirming the suitability of the used activated sludge inoculum and fulfilling the validity criteria mentioned in the relevant test guideline. The reference substance was degraded to 91 % of the ThOD_NH4 after 28 days.

Description of key information

The test substance  was tested in a manometric respirometry test according to the OECD Guideline for Testing of Chemicals, No. 301 F for 28 days to determine whether the test substance is readily biodegradable. At the end of the test period a biodegradation rate of 34 % of the ThODNH4 was measured. Because the biodegradation rate was < 60 % of the ThODNH4 after 28 days, the test substance cannot be considered to be readily biodegradable under test conditions. However, the present study indicates that moderate biodegradation presumably will occur in the environment.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

Although 1,3,3-trimethyl-N-(2-methylpropylidene)-5-[(2-methylpropylidene)amino]cyclohexanemethylamine has to be considered as not readily biodegradable a significant degradation potential could be observed (34% in 28 days).