Benzothiazole

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP - Guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

(2008)

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

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

Version / remarks:

(1992)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Benzothiazole

EC Number:

202-396-2

EC Name:

Benzothiazole

Cas Number:

95-16-9

Molecular formula:

C7H5NS

IUPAC Name:

benzothiazole

Details on test material:

- Name of test material (as cited in study report): Benzothiazol (BT Crude Quality)
- Analytical purity: 97.0 %
- Lot/batch No.: tank B 134

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum: aeration tank of a wastewater plant treating predominantly domestic sewage (Wupper area water authority, STP Odenthal)

- Preparation of inoculum for exposure:
=> the sludge was washed twice by adding mineral medium and centrifuging for 10 min at 2000 rpm and 20 °C and decanting off the supernatant
=> 1.348 g of the wet sludge was dried in order to calculate the amount of wet sludge to achieve a concentration of activated sludge of 3 g/L (dry weight) suspended solids
=> the calculated amount of sludge was first dissolved in mineral medium and then filled up to a defined end volume

- Storage conditions: room temperature, continuous shaking with aeration

- Storage length: max. 3 days

- Concentration of sludge: 30 mg/l

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Remarks:

(reported as BOD)

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral medium was prepared from stock solutions of 1) Mineral salt solution, 2) Magnesium sulphate solution, 3) Calcium chloride solution and 4) Iron (III) chloride solution
- preparation of medium: 10 mL of the mineral salt solution were mixed with 800 mL deionised water. Then 1 mL each of the magnesium sulphate-, calcium chloride- and the iron (III) chloride solution were added and filled up to 1 litre with deionised water.
- Test temperature: 22 ± 1 °C
- pH: 7.2 - 7.9 (at the end of the test)
- pH adjusted: no
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: OxiTop System (WTW) => closed respirometer flasks
- Mixing: 1 magnetic stirrer per test vessel
- Testvolume: 250 ml
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: consumed oxygen was replaced by electrolysis (maintaining a constant gas volume in the respirometer flasks)
- Details of trap for CO2: solution of potassium hydroxide


SAMPLING
- Sampling frequency: daily measurements of oxygen consumption


CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 2x (inocolum without test substance)
- Abiotic sterile control: no
- Toxicity control: yes, 1x (test substance and reference compound mixed)

Reference substance

Reference substance:

other: sodium benzoate (Fluka-BioChemika), Purity: 100 %, test concentration: 100 mg/l

Results and discussion

% Degradation

% Degradation 1

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

7 d

% Degradation 2

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

14 d

% Degradation 3

Parameter:

% degradation (O2 consumption)

Value:

58.4

Sampling time:

21 d

% Degradation 4

Parameter:

% degradation (O2 consumption)

Value:

74.3

Sampling time:

28 d

Details on results:

Toxicity control: The used concentrations of the test item did not show toxic effects to bacteria.
Oxygen uptake by nitrification: No nitrification was observed in the flasks with test item.
Degradation of reference compound: The reference compound reached the level for ready biodegradability within 14 days (BOD = 85%).

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Executive summary:

Lanxess, 2009:

A study was performed to assess the ready biodegradability of Benzothiazol (BT Crude Qualität).

The study was conducted in accordance with the Council Regulation (EC) No 440/2008, Method C.4-D "Manometric Respirometry Test" (2008). This test method is in all essential parts identical with OECD Guideline 301 F (adopted July 1992).

A solution of Benzothiazol (BT Crude Qualität) in a mineral medium was inoculated and incubated for 28 d under aerobic conditions. During this period, degradation was followed by BOD determinations.

Benzothiazol (BT Crude Qualität) showed:

0 % degradation after 7 days

0 % degradation after 14 days

58 % degradation after 21 days

74 % degradation after 28 days

Therefore, Benzothiazol (BT Crude Qualität) is considered to be "Readily Biodegradable".

The reference compound sodium benzoate showed 85 % degradation after 14 days.