1,2,4-trichlorobenzene

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:

not given

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Deviations:

yes

Remarks:

duration was only 2 weeks

GLP compliance:

not specified

Specific details on test material used for the study:

- Name of test material (as cited in study report): 1,2,4-Trichlorobenzene
- Physical state: liquid (M.P. 17°C; B.P. 210°C)
- Analytical purity: not given
- Impurities (identity and concentrations): not given

Oxygen conditions:

aerobic

Inoculum or test system:

other: mixed inocolum

Details on inoculum:

Sludge sampling sites and time:
- in March, June, September, and December, sludge was sampled
- at the following 10 places in Japan: 1. Fukogawa city sewage plant, 2. Fukashiba industry sewage plant, 3. Nakahama city sewage plant, 4. Ochiai city sewage plant, 5. Kitakami river, 6. Shinano river, 7. Yoshino river, 8. Lake Biwa, 9. Hiroshima bay, 10. Dookai bay
- So a mixture of city and industry sewage and river, lake and sea surface water and soil was tested.

Sampling method:
1. City sewage: Returned sludge from sewage plants was taken.
2. Rivers, lake and sea: Surface water and surface soil which were in contact with atmosphere were collected.

Method of cultivation - Mixing of fresh and old activated sludge:
5 L of the filtrate of the supernatant of old activated sludge was mixed with 500 mL of the filtrate of the supernatant of new sludge and cultured at pH 7.0 ± 1.0 under sufficient aeration using prefiltered open air.

Method of cultivation - Culture:
About 30 minutes after ceasing aeration to the sludge mixture, supernatant corresponding to about 1/3 of the whole volume was removed. Then the equal volume of dechlorinated water was added to the remaining portion and aerated again, followed by addition of synthetic sewage at a concentration of 0.1% (w/v). This procedure was repeated once every day. The culturing was carried out at 25 ± 2 °C.

Method of cultivation - Control:
During the cultivation, appearance of the supernatant, precipitability, formation of flock, pH, dissolved oxygen concentration in the solution and temperature were checked and necessary adjustments were made, Microflora in the activated sludge was microscopically observed and sludge with no abnormal symptom was used for the test.

Inspection of activity:
Activity of the sludge was insepected to use reference substance. And the relation between new and old activated sludge was taken account.

Adaptation:
There is no specific statement about the adaptation of the used microorganisms but the sampling sides and culture conditions suggest not adapted microorganisms.

Concentration of sludge:
30 mg/L

Duration of test (contact time):

2 wk

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Test performed in open system: no => taking into account the volatile character of 1,2,4-TCB

Preparation of basal culture medium (sludge):
- Suspended solids concentration: determined according to Method Japanese Industrial Standards (JIS) K 0102-1986-14.1
- Composition of basal culture medium: 3 mL each of four stock solutions, as described in JIS K 0102-1986-21, are diluted to 1000 mL with purified water
- pH of basal culture medium: 7.0
- pH adjusted: yes

Test system:
- Abiotic sterile control: 300 ml purified water + 30 mg test substance
- Test solution: 300 ml basal culture medium (sludge) + 30 mg test substance
- Reference: 300 ml basal culture medium (sludge) + 30 mg aniline
- Inoculum blank: 300 ml sludge

Test instruments and conditions:
- Culturing apparatus: Closed system oxygen consumption measuring apparatus (Coulometer: Ohkura Electric Co., Ltd.)
- Vessel size: 300 mL in volume
- absorbent for evolving carbon dioxide: Soda lime No .l (extra pure reagent, Wako Pure Chemical Industries, Ltd.).
- stirring method: test solution was stirred by a magnetic stirrer
- cultivating temperature: 25 ± 1°C
- reference substance: aniline

Analysis after termination of the test:
- TOC
- test substance
- pH

Parameter followed for biodegradation estimation:
- oxygen consumption

Reference substance:

aniline

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

2 wk

Validity criteria fulfilled:

not specified

Interpretation of results:

under test conditions no biodegradation observed

Executive summary:

MITI (1992)

 

The ready biodegradability was studied with a method corresponding to the OECD TG 301C, Modified MITI (I) test. The test concentration was 100 mg/l and activated sludge concentration 30 mg/l. In the aerobic study, the degradation measured as Biochemical Oxygen Demand (BOD) was 0% after 14 days. However, the high concentration of 1,2,4-TCB employed in the test may have resulted in toxicity to the microorganisms (EU RAR, 2003). Anyhow the result of this study is valid due to an high EC50 value of 500 mg/l in the only performed OECD-guideline study on toxicity to activated sludge (Yoshioka et al., 1986).

Description of key information

Biodegradation in watrer: screening tests

The ready biodegradability was studied with a method corresponding to the OECD TG 301C, Modified MITI (I) test (1992). The test concentration was 100 mg/l and activated sludge concentration 30 mg/l. In the aerobic study, the degradation measured as Biochemical Oxygen Demand (BOD) was 0% after 14 days. However, the high concentration of 1,2,4-TCB employed in the test may have resulted in toxicity to the microorganisms (EU RAR, 2003). Anyhow the result of this study is valid due to an high EC50 value of 500 mg/l in the only performed OECD-guideline study on toxicity to activated sludge (Yoshioka et al., 1986).

 

 

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater