2-ethylhexyl 3-mercaptopropionate

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:

1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

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

Deviations:

not specified

GLP compliance:

not specified

Specific details on test material used for the study:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic, non-adapted

Details on inoculum:

Sewage from STP Taunusstein-Bleidenstadt (Batch 29.10.96)

Duration of test (contact time):

28 d

Initial conc.:

44.29 mg/L

Based on:

ThCO2

Remarks:

Exp. 1

Initial conc.:

20 mg/L

Based on:

test mat.

Remarks:

Exp. 1

Initial conc.:

73.71 mg/L

Based on:

DOC

Remarks:

Exp. 2

Initial conc.:

34.29 mg/L

Based on:

test mat.

Remarks:

Exp. 2

Parameter followed for biodegradation estimation:

CO2 evolution

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (CO2 evolution)

Value:

70

St. dev.:

1.41

Sampling time:

29 d

Validity criteria fulfilled:

not specified

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

Based on 70% biodegradation within 29 days, EHMP is readily biodegradable, but the 10-day window was failed. However, with ≥70% biodegradation, EHMP is considered easily biodegradable, according to the definition of Directive 93/21/EEC (18th ATP).

Executive summary:

The biodegradation of EHMP was investigated over a 28-day period in a CO2 Evolution Test according to OECD guideline 301 B. The test medium was inoculated with non-adapted activated sludge from a sewage treatment plant mainly fed with municipal wastewater. The rate of degradation was monitored by measuring the carbon dioxide produced over the 28-d period.

The percentage CO2 production was calculated in relation to the theoretical CO2 (ThCO2) of the test item. The biodegradation was calculated for each titration time.

 

The degradation at the end of the observation period was >60%, however, the 10 day window criterion was not fulfilled. Therefore, EHMP was not readily biodegradable in this study.

 

Description of key information

Based on 70% biodegradation in a CO₂ evolution test, EHMP is readily biodegradable, but the 10-day window was failed. However, with ≥70% biodegradation, EHMP is considered easily biodegradable, according to the definition of Directive 93/21/EEC (18th ATP).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable but failing 10-day window

Type of water:

freshwater