diethyl 1-(2,4-dichlorophenyl)-5-methyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylate

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:

28 Jun - 09 Aug 1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Municipal sewage treatment plant at Frankfurt-Sindlingen
- Type of inoculum : Centrifuged sediment from activated sludge was washed, centrifuged again and re-suspended
- Pre-conditioning : Aeration for 7 days in order to use up the carbon in the activated sludge

Duration of test (contact time):

42 d

Initial conc.:

28.1 - 32.5 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium:
Amount used : 3.3 ml/L activated sludge suspension with 8 g/L of the centrifuged sediment. The suspension contained 6.3 g/L dry matter, equivalent to 21 mg/L dry matter in the final volume of the test batch
State of acclimatisation : not acclimatised to the test substance or reference substance


TEST SYSTEM
- Reaction vessels: 5-1 glass flasks with magnetic stirrers into which CO2-free air was conducted. The outgoing air was conducted via three traps each filled with 100 ml 0.0125 m Ba(OH)2 to collect the CO2 produced.
- Number of culture flasks/concentration: 2
- Sampling: 25 ml samples from the CO2 traps for titration
- Analyses: titration of the unused barium hydroxide, calculation of the trapped CO2 and calculation of the amount of carbon released from the test material per test vessel.


SAMPLING
- Sampling frequency: on days 3, 7, 10, 14, 17, 21, 24, 28, 35, 41 and 42

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2
- Abiotic sterile control: no
- Toxicity control: no
- Other: reference substance, 2

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (CO2 evolution)

Value:

0.8

Sampling time:

21 d

Parameter:

% degradation (CO2 evolution)

Value:

0.2

Sampling time:

28 d

Parameter:

% degradation (CO2 evolution)

Value:

2.5

Sampling time:

42 d

Results with reference substance:

84% degradation after 17 d

Findings:

The release of carbon dioxide remained below 20% of the theoretical maximum at the end of the total test period of 42 days.Therefore no significant biodegradation was observed as for most pesticides.

 

Conclusion:

Testing of Hoe 107892 in the modified Sturm test showed that this substance is not readily biodegradable

in accordance with the definition given in the OECD Guidelines for the Testing of Chemicals. Significant

biodegradation was not observed. The release of CO2 remained below 20% of the theoretical maximum during the prolonged test period of 42 days.

Description of key information

The substance is not readily biodegradable according to OECD criteria.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater

Additional information

The ready biodegradability of the substance was tested in a GLP guideline study following OECD guideline 301B. Domestic, activated sludge (non-adapted) was used as incoculum. A degradation rate of 0.2% was determined after 28 days. The test period was prolonged to 42 days. At the end of the test period a degradation rate of 2.5% was reported.

Based on the results of the available test the substance is considered not readily biodegradable according to OECD criteria.