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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Well-documented OECD 301F GLP guideline study on the registered substance itself without deviations
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
OECD Guidelines for Testing of Chemicals (1992) No. 301F "Ready Biodegradability; Manometric Respirometry Test”
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Version / remarks:
Method C.4-D of Commission Regulation (EC) No. 440/2008
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 835.3110 (Ready Biodegradability)
Version / remarks:
US EPA Fate, Transport, and Transformation Test Guidelines OCSPP 835.3110 (Paragraph (q))
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
The Department of Health of the Government of the United Kingdom
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): A mixed population of sewage treatment micro-organisms was obtained on 7 December 2015 from the final effluent stage of the Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK, which treats predominantly domestic sewage.
- Preparation of inoculum for exposure: The sample of effluent was filtered through coarse filter paper (first approximate 200 mL discarded) and maintained on aeration in a temperature controlled room at 21 ± 1 ºC prior to use.
Duration of test (contact time):
28 d
Initial conc.:
25 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: The mineral medium used in this study was that recommended in the OECD Guidelines.
- Test temperature: 22 to 23 ºC
- pH: 7.5 (day 0) - 7.9 (max. at day 28)
- pH adjusted: no
- Continuous darkness: no, test was conducted in diffuse light

TEST SYSTEM
- Culturing apparatus: 500 mL bottles, The system consists of a sample flask sealed by a sensor head/CO2 trap immersed in a temperature controlled water bath. The samples were stirred for the duration of the test with a magnetically coupled stirrer.
- Number of culture flasks/concentration:
a) Three replicate bottles containing inoculated mineral medium to act as the inoculum control.
b) Two replicate bottles containing inoculated mineral medium and the reference item, aniline, at a concentration of 100 mg/L.
c) Three replicate bottles containing inoculated mineral medium and the test item at a concentration of 25 mg/L.
d) Two replicate bottles containing inoculated mineral medium, the reference item, aniline, at a concentration of 100 mg/L and the test item at a concentration of 25 mg/L to act as toxicity control vessels.
- Measuring equipment: Hach HQ40d Flexi handheld meter / CES Multi-Channel Aerobic Respirometer

SAMPLING
- Sampling frequency: BOD determined daily

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Toxicity control: yes
Reference substance:
aniline
Remarks:
Purity: 99.99 %, by Fisher Scientific, 100 mg/l
Preliminary study:
Results obtained from the Toxicity to Activated Sludge in a Respiration Inhibition Test showed 47% inhibition at the test concentration of 100 mg/L. Therefore following the recommendations of the Test Guidelines the test item at a reduced concentration of 25 mg/L was selected for use in the study.
Parameter:
% degradation (O2 consumption)
Value:
10
Sampling time:
28 d
Details on results:
The test item attained 10% biodegradation after 28 days, calculated from the oxygen consumption values, and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301F.
Results with reference substance:
Aniline (procedure control) attained 70% biodegradation after 14 days and 79% biodegradation after 28 days thereby confirming the suitability of the inoculum and test conditions.
Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
The study was performed according to OECD TG301F and EU Method C.4-D (GLP) without deviations and therefore considered to be of the highest quality (reliability Klimisch 1). The validity criteria of the test system are fulfilled. Within 28 days, a degradation of 10% was determined for the test substance via O2 consumption. Therefore, the test item is considered to be not readily biodegradable.
Executive summary:

The study was performed to assess the ready biodegradability of the test item (CAS 4016-14-2) in an aerobic aqueous media. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (1992) No. 301F, “Ready Biodegradability; Manometric Respirometry Test” referenced as method C.4-D of Commission Regulation (EC) No. 440/2008 and US EPA Fate, Transport, and Transformation Test Guidelines OCSPP 835.3110 (Paragraph (q)).

 

Results obtained from the Toxicity to Activated Sludge in a Respiration Inhibition Test showed 47% inhibition at the test concentration of 100 mg/L. Therefore following the recommendations of the Test Guidelines, the test item at a reduced concentration of 25 mg/L was exposed to sewage treatment micro-organisms with mineral medium in sealed culture vessels in diffuse light at temperatures between 22 and 23 ºC for 28 days.

The biodegradation of the test item was assessed by the measurement of daily oxygen consumption values on Days 0 to 28. Control solutions with inoculum and the reference item, aniline, together with a toxicity control were used for validation purposes.

 

The test item attained 10% biodegradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301F.

Description of key information

Biodegradation in water: screening tests: Not readily biodegradable: 10% (BOD) on 28 days (OECD 301F / EU method C.4 D)

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

There is a valid, Klimisch 1 OECD 301F (GLP) study on the registered substance itself available. It is hence considered as sufficiently reliable to cover this endpoint. The test item attained 10% biodegradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301F.

The tonnage-driven data requirements under REACH are fully met, no data gaps were identified and no additional testing needs to be performed, as there is no indication given that the available data is not reliable or suitable for further risk assessment. CAS 4016-14-2 needs consequently be regarded as not readily biodegradable.