1,3,5-triisopropylbenzene

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:

Jan 21 to Jun 26, 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: HJ/f 153-2004, The guidelines for the testing of chemicals [S]. Beijing: SEPA, 2004

Qualifier:

equivalent or similar to guideline

Guideline:

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

Version / remarks:

1992

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

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

Qualifier:

equivalent or similar to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

GLP compliance:

yes

Remarks:

According to the guidelines of chemical testing good laboratory practices in China

Specific details on test material used for the study:

Test substance H6362
Lot No: 6F11027000
Purity 96%
Expiry: 2 years
Appearance: Clear high boiling odorless liquid
Storage conditions: Keep container tightly closed. Store away from heat and light.

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic, non-adapted

Details on inoculum:

Samples of secondary effluent were obtained as the test inoculum from a sewage plant treating predominantly domestic sewage (Nanjing Chengdong Sewage Treatment Plant).

On the day of the test, the test inoculum was prepared by filtering the sample of sewage effluent through a coarse filter, (discarding the first 200 mL) and collecting the remaining filtrates. This inoculum was maintained under aerobic conditions in hte test area unitl use. The inoculum was not pre-conditioned at test temperature and was not pre-adapted to the test item. The test solutions were prepared in an inorganic mineral medium, inoculated with a small number of micro-organisms from a mixed population.

Duration of test (contact time):

ca. 28 d

Initial conc.:

ca. 2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of test medium: inorganic mineral medium
- Test temperature: 20°C
- pH: 6.68-7.03
- pH adjusted: no
- Aeration of dilution water: Dilution medium prepared by adding 1 mL each of the 4 stock solutions, prepared in pre-aerated deionized water to each litre of deionised water
- Suspended solids concentration: Not specified
- Continuous darkness: yes
- Other:

TEST SYSTEM
- Culturing apparatus: BOD-bottle
- Number of culture flasks/concentration: 4 groups (inoculum control, test group, procedure control, toxicity control): 4 bottles for toxicity control; 20 bottles for each of inoculum control, test group, and reference control
- Method used to create aerobic conditions: Laboratory supply of oil-free compressed air. BOD bottles aerated with hose which reached down to the bottom of the bottle
- Measuring equipment: Analytical balance, dissolved oxygen (DO) meter, pH meter
- Test performed in closed system: Yes, the BOD bottles were fully filled (total volume: 300 mL)
- Other: Test inoculum prepared by fiiltering sample of sewage effluent through coarse filter (first 200 mL discarded) and collecting remaining filtrates

SAMPLING
- Sampling frequency: DO measured made at 0, 2, 5, 7, 11, 14, 18, 21, 25 and 28 days (except for toxicity control - DO, pH, and temp taken at the start and after 14 days)
- Sampling method: DO meter
- Sample storage before analysis: Not specified

CONTROL AND BLANK SYSTEM
- Inoculum blank: contained inoculum only; O2 consumption reached 1.02 mg O2/L after 14d of incubation. Met the test criteria of <1.5 mg O2/L
- Procedure control: contained reference substance and inoculum; biodegradation of reference substance reached 91.6% w/in 14d. Met the test criteria of achieving 60% w/in 14d
- Toxicity control: contained test substance, reference substance, and inoculum. Degradation was 70.3% after 14d. Met the test criteria of no less than 25% in 14d.


STATISTICAL METHODS: Theoretical oxygen demand, oxygen consumption, and % biodegradability calculated

Reference substance:

benzoic acid, sodium salt

Remarks:

sodium benzoate

Key result

Parameter:

% degradation (O2 consumption)

Value:

ca. 73.3

Sampling time:

28 d

Remarks on result:

other: average value

Parameter:

% degradation (O2 consumption)

Value:

69.65

Sampling time:

25 d

Remarks on result:

other: average value

Parameter:

% degradation (O2 consumption)

Value:

68.6

Sampling time:

21 d

Remarks on result:

other: average value

Parameter:

% degradation (O2 consumption)

Value:

66

Sampling time:

18 d

Remarks on result:

other: average value

Parameter:

% degradation (O2 consumption)

Value:

64.6

Sampling time:

14 d

Remarks on result:

other: average value

Parameter:

% degradation (O2 consumption)

Value:

60.7

Sampling time:

11 d

Remarks on result:

other: average value

Parameter:

% degradation (O2 consumption)

Value:

56.2

Sampling time:

7 d

Remarks on result:

other: average value

Parameter:

% degradation (O2 consumption)

Value:

47.2

Sampling time:

5 d

Remarks on result:

other: average value

Parameter:

% degradation (O2 consumption)

Value:

5.32

Sampling time:

2 d

Remarks on result:

other: average value

Details on results:

The results showed that the average biodegradation rate of H6362 was 73.3% after 28-days and about 64% at 10-d window, based on the calculation of ThOD(NO3).

Results with reference substance:

The biodegradation of the reference substance achieved 91.6 % within 14 days.

The test is valid because the biodegradation of the reference substance achieved 91.6 % within 14 days, meeting the test criteria of achieving 60% within 14 days. Oxygen consumption in inoculated blanks was 1.02 mg O2/L after 14 days of incubation, meeting the test criteria of less than 1.5 mg O2/L. Degradation in the toxicity control was 70.3% after 14 days, meeting the test criteria of no less than 25% in 14 days. The result indicated that the test substance was not toxic to the inoculum. Additionally, the lowest level of dissolved oxygen in test substance group was 2.99 mg O2/L, which did not fall below 0.5 mg O2/L and the difference of biodegradation of the test item in the two replicates was less than 20%. Thus, all validity criteria listed in Section 4.4 were met. Therefore the test is considered valid.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The study results showed that under the valid conditions, the average biodegradation rate of the test item was 73.3% after 28-days and about 64 % at the 10-d window. It would therefore be considered readily biodegradable, as it achieved the 10-d pass level (60% ThOD) stated in the OECD 301 Method.

Executive summary:

The study results showed that under the valid conditions, the average biodegradation rate of the test item was 73.3% after 28-days and about 64% at the 10-d window. It would therefore be considered readily biodegradable, as it achieved the 10-day pass level (60% ThOD) stated in the OECD 301 Method.

Description of key information

The results showed that the average biodegradation rate of H6362 (test substance) was 73.3% after 28-days and about 64% at 10-day window, based on the calculation of ThOD(NO3).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The REACH Guidance on Information Requirements Chapter R.7b indicates that a pass level of 60% theoretical oxygen demand (ThOD; TG 301 C, TG 301 D and TG 301 F) obtained within 28 days, may be regarded as evidence of ready biodegradability. Therefore, the substance can be considered as readily biodegradable.