REAKTIVE GELB F 97494

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:

From October 17, 2001 to November 14, 2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

Type: mixed population of aquatic microorganisms (activated sludge)
Origin: aeration tank of a waste water plant treating predominantly domestic sewage (Kläranlage Odenthal)
Date of collection: October 15, 2001
Pretreatment: none
Concentration of inoculums: 30 mg/L SS

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

PRETREATMENT OF THE TEST SUBSTANCE
25 mg test substance was weighed out on aluminium foil. This substance inclusive of the aluminium foil was added to the test vessels to give a test concentration of 100 mg/L test substance.

EXPOSURE CONDITIONS
Test volume: 250 mL
Test apparatus: Voith Sapromat
Type of system: closed
Mixing: one magnetic stirrer per test vessel
Incubation time: 28 d
Incubation temperature: 20±1°C

CHEMICAL ANALYSIS
Nitrate-N/Nitrite-N method: Determination of nitrite nitrogen and nitrate nitrogen and the sum of both by flow analysis (CFA and FIA) and spectrometric detection. The nitrate and nitrite concentration at 0 h was determined from a flask with test substance. Therefore an additional determination of nitrate and nitrite of the blank inoculum was not necessary.
Standard: EN ISO 13395
Test apparatus: Continuous Flow Analyser SKALAR SAN Plus System

Reference substance:

benzoic acid, sodium salt

Remarks:

99% pure

Test performance:

The used concentrations of the test substance did not show toxic effects to bacteria.

Parameter:

other: Biochemical oxygen demand

Value:

8

Sampling time:

28 d

Remarks on result:

other: The consumption of oxygen was determined by measuring the quantity of oxygen (produced electrolytically) required to maintain constant gas volume in the respirometer flask.

Details on results:

pH of the test vessel: 7.5

Degradation of test substance:
2% degradation after 2 d
4% degradation after 6 d
5% degradation after 8 d
8% degradation after 12 d
8% degradation after 14 d
8% degradation after 16 d
9% degradation after 20 d
11% degradation after 22 d
13% degradation after 26 d
8% degradation after 28 d

Results with reference substance:

Degradation of reference substance:
56% degradation after 2 d
76% degradation after 6 d
82% degradation after 8 d
89% degradation after 12 d
90% degradation after 14 d
91% degradation after 16 d
92% degradation after 20 d
93% degradation after 22 d
94% degradation after 26 d
94% degradation after 28 d

All validity criteria of the test method were met:

 

-The reference compound reached the level for ready biodegradability by Day 14.

-No toxicity of the test substance was observed in the toxicity control group.

-The difference of extremes of replicate values of the removal of test chemical at the end of the test was less than 20%.

-The oxygen uptake of the inoculums blank was ≤60 mg/L.

-The pH was within the range of 6.5- 8.5 in the test vessels at the end of the test (applicable in case where degradation is less than 60%).

Validity criteria fulfilled:

yes

Interpretation of results:

other: not readily biodegradable

Conclusions:

Under the study conditions, the test substance was considered to be 'not readily biodegradable' in the closed bottle test, with 8% biodegradation at 28 d.

Executive summary:

A study was conducted to assess the ready biodegradability of the test substance according to the EU Method C.4 -D (which is in most parts equivalent to OECD Guideline 301 F), in compliance with GLP.

100 mg/L of the test substance was inoculated in triplicates with non-adapted activated sludge in a closed flask at a constant temperature (20 ± 1 °C) for up to 28 d. Degradation was assessed by the determination of Biochemical Oxygen Demand (BOD) on Days 2, 6, 8, 12, 14, 16, 20, 22, 26 and 28. A toxicity test and a control solution containing the reference substance benzoic acid, sodium salt (100 mg/L) together with inoculum were used for validation purposes. The test substance degraded 2, 4, 5, 8, 8, 8, 9, 11, 13 and 8% on Days 2, 6, 8, 12, 14, 16, 20, 22, 26 and 28, respectively. No toxicity of the test substance was observed in the toxicity control. The reference compound showed 90% degradation at Day 14.

Hence, under the study conditions, the test substance was considered to be ‘not readily biodegradable’.

Description of key information

Under the study conditions, the test substance was considered to be 'not readily biodegradable' in the closed bottle test, with 8% biodegradation at 28 d.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater

Additional information

A study was conducted to assess the ready biodegradability of the test substance according to the EU Method C.4 -D (which is in most parts equivalent to OECD Guideline 301 F), in compliance with GLP. 100 mg/L of the test substance was inoculated in triplicates withnon-adapted activated sludge ina closed flask at a constant temperature (20 ± 1 °C) for up to28 d. Degradation was assessed by the determination of Biochemical Oxygen Demand (BOD) on Days 2, 6, 8, 12, 14, 16, 20, 22, 26 and 28. A toxicity test and a control solution containing the reference substance benzoic acid, sodium salt (100 mg/L) together with inoculum were used for validation purposes. The test substance degraded 2, 4, 5, 8, 8, 8, 9, 11, 13 and 8% on Days 2, 6, 8, 12, 14, 16, 20, 22, 26 and 28, respectively. No toxicity of the test substance was observed in the toxicity control. The reference compound showed 90% degradation at Day 14. Hence, under the study conditions, the test substance was considered to be ‘not readily biodegradable’.