reaction mass of [(1R*,5S*)-3,3,5-trimethylcyclohexyl] acetate and [(1S*,5S*)-3,3,5-trimethylcyclohexyl] acetate

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:

16 Mar - 13 Apr 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)

GLP compliance:

yes (incl. QA statement)

Remarks:

Staatliches Gewerbeaufsichtsamt, Hildesheim, Germany

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Municipal sewage treatment plant, Hildesheim, Germany
- Initial cell/biomass concentration: 10E+5 - 10E+8 Colony Forming Units (CFU)/L
- Pretreatment: Activated sludge was washed twice with autoclaved tap water; settled sludge resuspended in mineral salt medium; maintained under aerobic condition by aeration for 4 hours; homogenized with a blender; supernatant decanted and maintained under aerobic conditions by aeration with CO2-free air for 2 days; 10 mL/L used to initiate inoculation

Duration of test (contact time):

28 d

Initial conc.:

20 mg/L

Based on:

test mat.

Initial conc.:

14.3 mg/L

Based on:

other: Carbon

Parameter followed for biodegradation estimation:

inorg. C analysis

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral salts medium according to guideline
- Test temperature: 21 - 23 °C, down to 20 °C for 18 h
- Continuous darkness: No, low light conditions

TEST SYSTEM
- Culturing apparatus: Headspace flasks / 120 mL; ratio headspace to liquid 1/2
- Number of culture flasks/concentration: 3 replicates (test end 5 replicates)
- Method used to create aerobic conditions: Shaker, 150 - 200 rpm
- Measuring equipment: Carbon analyser, Multi N/C 3000 (analysis according to DIN EN 1484)
- Test performed in closed vessels: yes (septum)
- Test performed in open system: no

SAMPLING
- Sampling frequency: Sampled on day 0, 2, 5, 7, 12, 14, 21, 28
- Sampling method: IC analysis
- Sample storage before analysis: Stored at 6 ± 2 °C

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 3 replicates (test end 5 replicates)
- Abiotic sterile control: no
- Toxicity control: yes, 3 replicates (test end 5 replicates)
- Functional control: yes, 3 replicates (test end 5 replicates)

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (CO2 evolution)

Value:

62

Sampling time:

28 d

Remarks on result:

other: 95% confidence interval (43 - 81%)

Details on results:

- 10% degr. reached after 3 days
- 62% degr. reached after 28 days

Results with reference substance:

Functional control (sodium benzoate): pass level (60% ) reached after 3 days (92% after 28 days)
Toxicity control: 57% degradation within 14 days (74% after 28 days)

Table 1: Degradation of the reference substance and in the toxicity control

Day	Reference substance [%]	Toxicity control [%]
2	54
5	76
7	80	53
12	86
14	90	57
21	87	61
28	92	74

 

Table 2: Degradation measurement test item (CO2 evolution and degradation rate):

Day	CO2-Production  [mg C/L]	Mean production NaOH corrected  [mg C/L]	Degr. [%]
0	3.30 3.16 3.14	0.76	-
2	5.07 5.02 5.22	2.50	9
5	7.22 7.24 6.33	3.74	15
7	7.10 6.92 6.87	3.75	14
12	8.51 8.34 8.18	4.30	17
14	6.85 8.92 5.70	5.11	24
21	10.89 12.95 9.56	8.80	47
28	10.42 14.47 14.25 14.40 10.30	11.04	62

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test substance was degraded to 62% after 28 d. Since the substance is a multi-constituent substance consisting of an isomeric mixture the 10-day window should not be applied and the substance is considered to be readily biodegradable.

Description of key information

Readily biodegradable: 62% degradation after 28 d (OECD 310)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

One experimental study is available investigating the biodegradability of the test substance. The study was performed according to the OECD 310 (GLP). Non-adapted, domestic activated sludge from a sewage treatment plant was used as inoculum. After 28 d a mean degradation of 62% was recorded based on CO2-evolution but the 10-day window was not met. Since the substance is an isomeric mixture, the 10-day window should no be applied for the assessment. Thus, the test substance is considered to be “readily biodegradable”. A toxicity control containing both, reference substance and test substance, did not indicate inhibitory effects to the inoculum (57% degradation after 14 d). All validity criteria of the study were met.