Benzethonium chloride

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:

August - October 2001

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

TEST MATERIAL
- Identity: LZ1442.3, Benzethonium chloride
- Chemical name: Benzethonium chloride
- Appearance: White powder
- Storage conditions: Room temperature
- Stability under test conditions: stable for min. 3 years from manufacturing date
- Batch No.: OC0509
- Expiry date: 7 June2002
- Purity: Responsibility of sponsor
- Date received: 20 August 2001
- Safety precautions: Routine safety precautions (lab coat, gloves, safety glasses, face mask) for unknown materials were applied to assure personnel health and safety.

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic (adaptation not specified)

Details on inoculum:

A sample of activated sludge was collected from Eye sewage treatment works, which treats predominantly domestic waste. Aliquots (25 ml) of a homogenised sample were filtered through dried (approximately 105°C) and pre-weighed Whatman GFC filter papers. The filters were dried for
at least one hour, allowed to cool and re-weighed. The solids level in the sludge was determined and then an appropriate volume used to inoculate control and test vessels to give a final suspended solids concentration of 30 mg/1.

Duration of test (contact time):

28 d

Initial conc.:

5 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral salts medium
- Solubilising agent (type and concentration if used):
- Test temperature:none
- pH: The pH of all test and control mixtures was 7.6 at the start of the test and ranged between 7.4 and 7.5 at the end.
- pH adjusted: yes; and adjusted, as required, with 5N HCl to 7.4 ± 0.2. Each vessel was then fitted with a stopper holding an air inlet tube reaching approximately 10 cm, below the liquid surface and an air outlet just below the stopped:
- Suspended solids concentration: 30 mg/L
- Continuous darkness: no

TEST SYSTEM
- Culturing apparatus: 5 l amber glass bottles
- Number of culture flasks/concentration: six
- Test performed in closed vessels due to significant volatility of test substance: no
- Test performed in open system: yes
- Details of trap for CO2 and volatile organics if used: three Dreschel bottles in series, each containing 0.025N, nominal barium hydroxide (100 ml).

Reference substance:

benzoic acid, sodium salt

Remarks:

(AR grade, product number S/2441/53) was obtained from Fisher Scientific UK.

Preliminary study:

no pretest performed

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

2 d

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

9 d

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

21 d

Key result

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

28 d

Details on results:

There was no evidence of biodegradation (0% degradation) of Benzethoniumchloride by the end of the test on Day 29.

Remarks on result:

not measured/tested

Results with reference substance:

The results obtained for the degradation of sodium benzoate (70% of its TC02 after 7 days and 95%after 29 days) and for cumulative C02 production by the control mixtures (55.6 and 58.3 mgC02) fulfil the validity criteria for this test.

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

There was no evidence of biodegradation (0%) of Benzethoniumchloride by the end of the test on Day 29.

Executive summary:

The objective of this study was to assess the biotic degradability of Benzethoniumchloride. It was conducted in accordance with Procedure C.4-C "C02 Evolution test" of the Annex to Directive 92/69/EEC (OECD 301B). In order to allow an assessment of ready biodegradability using this test method, a test substance concentration of 5 mg as Carbon/l was employed. This level was lower than the guideline recommendation of 10- 20 mgC/l because Benzethoniumchloride was expected to have adversely affected the activity of the microbial inoculum at a higher concentration owing to its antimicrobial properties. The degradable reference substance sodium benzoate was also employed at 5 mgC/l in order to demonstrate that the precision of the assay had not been affected by the use of a lower test substance concentration.

There was no evidence of biodegradation of Benzethoniumchloride by the end of the test on Day 29. Sodium benzoate had been biodegraded by 70% after 7 days and 95% after 29 days in the absence of Benzethoniumchloride, and by 60% after 5 days in its presence which confirmed that the test item was not inhibitory to the activity of the microbial inoculum.

Description of key information

The biotic degradability test of Benzethoniumchloride was conducted in accordance with EU testing method C.4 -C "C02 Evolution test" and OECD no. 301B. There was no evidence of biodegradation of Benzethoniumchloride by the end of the test on Day 29. The test item was not inhibitory to the activity of the microbial inoculum.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

Source: GLP report