Isooctyl 3-mercaptopropionate

Toxicity to microorganisms

Administrative data

Endpoint:

toxicity to microorganisms, other

Remarks:

biodegradation test, toxicity control

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Isooctyl 3-mercaptopropionate

EC Number:

250-157-6

EC Name:

Isooctyl 3-mercaptopropionate

Cas Number:

30374-01-7

Molecular formula:

C11H22O2S

IUPAC Name:

2-methylheptyl 3-sulfanylpropanoate

Details on test material:

- Name of test material (as cited in study report): Isooctyl 3-mercaptopropionate (IOMP)
- Substance type: clear colourless liquid
- Physical state: liquid
- Analytical purity: no data
- Lot/batch No.: 0000020703
- Storage condition of test material: room temperature over silica gel in the dark

Test organisms

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): from aeration stage of the Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK, obtained 5 Nov 2007
- Method of cultivation: continuous aeration, approx. 21°C, in lab
- Storage length: 1 day
- Preparation of inoculum for exposure: activated sewage sludge sample was washed three times by settlement and resuspension in culture medium to remove any excessive amounts of DOC
- Concentration of sludge: suspended solid concentration was equal to 2.6 g/L prior to use; determination: 100 mL of washed activated sludge were filtered by suction through preweighed GF/A filter paper using a Buchner funnel. Filtration was then continued for further 3 min after rinsing the funnel three successive times with 10 mL of deionised reverse osmosis water. Filter paper was dired in an oven at approx. 105°C for at least 1 hour and allowed to cool before weighing. Process was repeated until a constant weight was attained.

Study design

Test type:

static

Water media type:

freshwater

Total exposure duration:

28 d

Results and discussion

Effect concentrations

Duration:

14 d

Dose descriptor:

IC10

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks on result:

other: toxicity control in ready biodegradation test

Applicant's summary and conclusion

Conclusions:

The toxicity control attained 82% degradation after 14 days and 84% degradation after 28 days thereby confirming that the test material was not toxic to the sewage treatment micro-organisms used in the test.

Executive summary:

A study was performed to assess the ready biodegradability of the test material iOMP in an aerobic aqueous medium on accordance with OECD TG 301 B.

The test material, at a concentration of 10 mg Carbon/l, was exposed to activated sewage sludge micro-organisms with culture medium in sealed culture vessels in the dark at approximately 21°C for 28 days.
The degradation of the test material was assessed by the determination of carbon dioxide produced. Control solutions with inoculum and the standard material, sodium benzoate, together with a toxicity control were used for validation purposes.

For the purposes of the test a toxicity control, containing the test material and sodium benzoate, was prepared in order to assess any toxic effect of the test material on the sewage sludge microorganisms used in the test.
An amount of test material (49.5 mg) was dispersed in approximately 400 ml of culture medium and subjected to high shear mixing at approximately 7500 rpm for approximately 15 minutes prior to dispersal in inoculated culture medium. An aliquot (51.4 ml) of the sodium benzoate stock solution was also added to the test vessel and the volume adjusted to 3 litres to give a final concentration of 16.5 mg test material/l plus 17.1 mg sodium benzoate/l, equivalent to a total of 20 mg carbon/l.

The test material attained 55% degradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No 301B.

The toxicity control attained 82% degradation after 14 days and 84% degradation after 28 days thereby confirming that the test material was not toxic to the sewage treatment micro-organisms used in the test.