Reaction mass of 5-[(Disubstituted-dihydrocarbopolycyclyl)diazenyl]-6-hydroxy-4-methyl-2-substituted-1-propyl-1,2-dihydropyridine-3-carbonitrile and 1-Butyl-5-[(disubstituted-dihydrocarbopolycyclyl)diazenyl]-6-hydroxy-4-methyl-2-substituted-1,2-dihydropyridine-3-carbonitrile

Biodegradation in water: screening tests

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Administrative data

Endpoint:

biodegradation in water: screening test, other

Remarks:

inherent biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2006

Report date:

2006

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II))

Deviations:

yes

Remarks:

Activated sludge from only one source was used. - The test water according to OECD Guideline for Testing of Chemicals No. 301 F, Ready Biodegradability: Manometric Respirometry Test, 1992 was used. - Only the biological oxygen demand (BOD) was monitored.

Principles of method if other than guideline:

None

GLP compliance:

yes (incl. QA statement)

Test material

Reference

Name:

Unnamed

Type:

Constituent

Test material form:

solid

Details on test material:

Batch: P2/05 UL
Appearance: light orange crystalline powder
Expiration date: 31.05.2011
Storage: at room temperature

Specific details on test material used for the study:

None

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

The study was performed with aerobic activated sludge from a wastewater treatment plant (ARA Ergolz II, Füllinsdorf, Switzerland) treating predominantly domestic wastewater. The sludge was washed twice with tap water by centrifugation and the supernatant liquid phase was decanted. A homogenized aliquot of the final sludge suspension was weighed, thereafter dried and the ratio of wet to dry weight was calculated.
Based on this ratio, calculated amounts of wet sludge were suspended in test water to obtain a concentration equivalent to 4 g dry material per liter (±10%). During holding, the sludge was aerated at room temperature until use. Prior to use, the sludge was diluted with test water to a concentration of about 1 g dry material per liter. Based on the determined dry weight of this diluted activated sludge, defined amounts of activated sludge were added to test water to obtain a final concentration of 100 mg dry material per liter.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

30 mg/L

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

The test item was weighed by means of an analytical balance and transferred to the test flask with test water. No emulsifiers or solvents were used but ultrasound dispersion was employed for 15 minutes to obtain a suspension of the test item as homogeneous as possible.

Apparatus:
The test flasks (500-mL Erlenmeyer flasks, labeled with all necessary information to ensure unmistakable identification) were incubated under continuous stirring in a SAPROMAT D12 (Voith GmbH, Heidenheim, Germany). Oxygen consumption was recorded manually by taking a daily reading at least on each working day.

Principle:
Electro-chemical analysis process:
The biodégradation process consumes the dissolved oxygen in the liquid and generates CO2. The CO2 is adsorbed by soda lime and the total pressure decreases in the airtight test flasks. The pressure drop is detected and converted into an electrical signal by means of an electrode type manometer. The consumed oxygen is replaced by electrolytically generated oxygen from a copper sulfate solution.

Test duration: 28 days

Light conditions: Darkness

Test temperature: 22 °C, maintained with a built-in thermostat and checked once per week.

pH: Prior to test start, the pH was measured in each test flask before the addition of the activated sludge inoculum. At the end of incubation, the pH was measured again in each test flask.

Reference substance

Reference substance:

other: sodium benzoate

Results and discussion

Preliminary study:

None

Test performance:

The test item had no inhibitory effect on activated sludge microorganisms at the test concentration of 100 mg/L and no degradation of the test item occurred in the abiotic control as determined in the ready biodegradability study for the test item (RCC Study No. A21510).

% Degradation

Key result

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Remarks on result:

other: FAT 41039/A was found not to be biodegradable

Details on results:

The percent biodégradation of the test item was calculated based on the chemical oxygen demand (COD) of 1.98 mg 02/mg test item.
The biochemical oxygen demand (BOD) of the test item FAT 41039/A in the test media was in the normal range found for the inoculum controls throughout the study period of 28 days.

BOD5 / COD results

Results with reference substance:

The percent biodégradation of the reference item sodium benzoate was calculated based on the theoretical oxygen demand of 1.67 mg 02/mg.
In the procedure controls, the reference item (sodium benzoate) was degraded by an average extent of 74% and 84% by exposure days 7 and 14, respectively, thus confirming the suitability of the activated sludge. At the end of the test (Day 28), the reference item was degraded by an average extent of 89%.

Any other information on results incl. tables

None

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not inherently biodegradable

Conclusions:

FAT 41039/A was found not to be biodegradable under the conditions of the test within 28 days.

Executive summary:

The test item FAT 41039/A was investigated for its inherent biodegradability in a manometric respirometry test over 28 days based on the OECD Guideline for Testing of Chemicals No. 302 C (1981).

The biochemical oxygen demand (BOD) of the test item FAT 41039/A in the test media was in the normal range found for the inoculum controls.

In the procedure controls, the reference item (sodium benzoate) was degraded by an average extent of 74% and 84% by exposure days 7 and 14, respectively, thus confirming the suitability of the activated sludge. At the end of the test (Day 28), the reference item was degraded by an average extent of 89%.

Thus, FAT 41039/A was found not to be biodegradable under the conditions of the test within 28 days.