1,1-dimethoxycyclododecane

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:

01 Mar - 28 Mar 1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: laboratory culture
- Laboratory culture: yes; activated sludge from a laboratory culture. Wastewater from a domestic sewage treatment plant was used for the culture. Activated sludge for the study was taken on 29 Feb 1996.

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: according to guideline
- Test temperature: 20 ± 1 °C
- Suspended solids concentration: 30 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Number of culture flasks/concentration: 3
- Measuring equipment: respirometer recording O2 consumption

SAMPLING
- Sampling method: direct measurement from respirometer

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 3 bottles
- Abiotic sterile control: no
- Toxicity control: yes, 2 bottles
- Other: reference substance: yes, 3 bottles

Reference substance:

aniline

Parameter:

% degradation (O2 consumption)

Value:

71

Sampling time:

28 d

Remarks on result:

other: Mean of three replicates

Details on results:

71% degradation was observed after 28 d. Since the 10-day window was not met, the substance is not readily biodegradable according to the OECD criteria.

Results with reference substance:

77% (mean) after 28 d, 60% pass level was reached.

Table 1: Degradation of the test substance

		Day of sampling
	Replicate	4	6	8	12	14	18	20	22	26	28
Corrected BOD [mg O2/L]	1	1	1	3	70	92	124	137	149	177	182
	2	8	8	17	83	104	131	143	152	176	186
	3	2	8	21	94	134	168	180	191	218	231
% degradation	1	0	0	1	25	33	44	49	53	63	65
	2	3	3	6	30	37	47	51	54	63	66
	3	1	3	8	34	48	60	64	68	78	82
% degradation (mean)	-	1	2	5	30	39	50	55	58	68	71

Conclusion in the test report is not correct. In the test report the substance is considered to be "readily biodegradable". However, the 10-day window was not considered for this final conclusion.

The toxicity control attained 43% degradation after 14 d indicating that the test substance is not inhibitory to the inoculum.

Validity criteria fulfilled:

yes

Interpretation of results:

other: biodegradable, but failing the 10-day window

Conclusions:

The test substance is biodegradable, but failing the 10-day window. Moreover, the inoculum is not inhibitory to the inoculum as the toxicity control attained 43% degradation within 14 d.

Description of key information

The substance cannot be considered as readily biodegradable, because the 10-day window was not passed (71% after 28 d; O2 consumption; EU Method C.4-D)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable but failing 10-day window

Additional information

One experimental study is available investigating the ready biodegradability of the test substance. The study was performed according to the EU Method C.4-D. Activated sludge from a municipal sewage treatment plant was used as inoculum. 71% degradation of the test substance was recorded based on O2 consumption after 28 d. Since the 10-day window was not met the test substance is considered to be not readily biodegradable. The toxicity control (containing both, reference substance and test substance) attained 43% after 14 d. Thus, the test substance is not considered to be inhibitory to the inoculum.