3-methylbutyl isovalerate

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:

2008-12-09 to 2009-05-18

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1992

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

2008

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

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 (e.g. location, sampling depth, contamination history, procedure): wastewater treatment plant of Geneva (Peney-Dessous), sampled on day of test start
- Pretreatment: washed with mineral medium and centrifugated three times, kept aerobic
- Concentration of sludge: 30 mg dw/L in test medium

Duration of test (contact time):

29 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral medium according to OECD 301F
- Test temperature: 22°C
- pH: 7.6
- pH adjusted: yes
- Suspended solids concentration: 1.53 g dw/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: Oxitop Control System

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Toxicity control: yes

Reference substance:

benzoic acid, sodium salt

Remarks:

analytical purity >99.0%

Preliminary study:

yes

Key result

Parameter:

% degradation (O2 consumption)

Value:

70

Sampling time:

28 d

Details on results:

The test substance showed no inhibitory effects on the microorganisms at the test concentration of 100 mg/L as estimated in the toxicity control.

Results with reference substance:

Degradability of sodium benzoate obtained from O2 consumption was 86% after 28 d. Therefore, the study is valid.

Biodegradation, mean [%] after n days
	1	2	12	21	28	29
Test substance* (mean of 2 values)	6	11	47	67	70	70
Reference substance (mean of 2 values)*	67	75	80	83	86	88

*Blank value considered

BOD, mean in [mg/O2/L] after n days
	1	2	12	21	28	29
Test substance* (mean of 2 values)	15.8	27.5	123.0	173.4	180.9	181.4
Reference substance* (mean of 2 values)	111.1	124.2	133.8	138.3	143.4	146.4
Toxicity control (mean of 2 values)	126.1	167.4	235.9	283.3	324.6	327.1

*Blank value considered

Validity criteria fulfilled:

yes

Interpretation of results:

other: biodegradable

Conclusions:

The biodegradation of the test item was determined in a GLP study according to OECD 301 F. Within the test period of 28 days, a degradation of 70 % was determined for the test substance. Furthermore, at the test concentration of 100 mg/L, no inhibitory effects on microorganisms from the test substance were observed as determined in the toxicity control. Given the 10 day window criteria is not fullfilled (11% biodegradation on day 2 and 47 % degradation on day 12), the substance is not readily biodegradable according to OECD criteria.

Description of key information

The biodegradation of test item was determined in two GLP studies according to OECD 301 F and OECD 301 D.

Key study: Within the test period of 28 days, a degradation of 70 % was determined for the test substance. In addition, at the test concentration of 100 mg/L, no inhibitory effects on the microorganisms from the test substance were observed as estimated in the toxicity control. Given the 10 day window criteria is not fullfilled (11% biodegradation on day 2 and 47 % degradation on day 12), the substance is not readily biodegradable according to OECD criteria.

Supporting study: Within the test period of 28 days a degradation of 24% was determined for the test substance. No inhibitory effects on microorganisms at the tested concentration of 2.9. mg/L reference substance and 2.7 mg/L test substance were observed due to a degradation of 49 % in 28 days measured as O2 consumption. According to OECD criteria the substance is not readily biodegradable.

 

Based on the study results and according to the criteria given in the ECHA Guidance (Guidance on the Application of the CLP Criteria) from 2015, the test substance can be considered for classification as not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable but failing 10-day window