1,1'-{(phenylmethanediyl)bis[(3-substituted benzene-4,1-diyl)diazene-2,1-diyl{1-[3-(dimethylamino)propyl]-2-hydroxy-4-methyl-6-oxo-1,6-dihydropyridine-5,3-diyl}]}dipyridinium chloride lactate salts

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:

February 04-March 05, 2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well documented study compliant with TG guideline and conducted under GLP in recognized contract research organization.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

ISO DIS 9439 (Ultimate Aerobic Biodegradability - Method by Analysis of Released Carbon Dioxide)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Reference

Name:

Unnamed

Type:

Constituent

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: municipal sewage treatment plant: 'Waterschap de Maaskant', 's-Hertogenbosch, The Netherland
- Method of cultivation / Preparation of inoculum for exposure: The freshly obtained sludge was kept under continuous aeration until further treatment. The concentration of suspended solids was 4.0 g/l in the concentrated sludge (information obtained from the municipal sewage treatment plant). Before use, the sludge was allowed to settle (34 minutes) and the liquid was decanted for use as inoculum.

Duration of test (contact time):

29 d

Initial test substance concentration

Initial conc.:

12 mg/L

Based on:

other: Total organic carbon (TOC)

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: synthetic mineral medium according to guideline, prepared using tap-water purified by reverse osmosis (Milli-RO) and subsequently passed over activated carbon and ion-exchange cartridges (Milli-Q) (Millipore Corp., Bedford, Mass., USA). Preparation of mineral medium
- Test temperature: 21.5-22.5 °C
- pH: test start: 7.6 (adjusted with 1 N HCl); test end (day 28): 7.5-7.8
- pH adjusted: yes
- Aeration of dilution water: Synthetic air (CO2 < 1 ppm) passed through a bottle, containing 0.5 - 1 litre 0.0125 M Ba(OH)2 solution at ca. 30-100 ml/min
- Suspended solids concentration: 10 ml/l (supernatant from activated sludge with 4g SS/l; see Details on inoculum)
- Continuous darkness: yes (all-glass brown coloured bottles)

TEST SYSTEM
- Culturing apparatus: all-glass brown coloured bottles
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: aeration with synthetic air (30-100 ml/min)
- Test performed in open system: no
- Details of trap for CO2: carbon dioxide was trapped in barium hydroxide and measured by titration as described in the guidelines

SAMPLING
- Sampling frequency:
- inoculum blank and test suspension: Day 2, 5, 7, 9, 13, 14, 19, 23, 27, and 29
- positive and toxicity control: Day 2, 5, 7, 9, 13, and 14

CONTROL AND BLANK SYSTEM
- Inoculum blank: inoculum (2 bottles)
- Toxicity control: test substance, sodium acetate and inoculum (1 bottle)

Reference substance

Reference substance:

acetic acid, sodium salt

Results and discussion

% Degradation

Parameter:

% degradation (CO2 evolution)

Value:

5

Sampling time:

29 d

BOD5 / COD results

Results with reference substance:

The reference substance sodium acetate was degraded by 61% within 14 days of exposure.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

Criteria of OECD Guideline 301B: Biodeg. of the ref. substance >60% within 14 days. Diff. of duplicate values for %-deg. <20. Total CO2 release in the blank at the end of the test <40 mg/l. IC of the test substance at the beginning of the test <5% of TC.

Interpretation of results:

under test conditions no biodegradation observed