2-(octylthio)ethanol

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009-05-08 to 2009-09-04

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study performed according to OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test) and EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test) without deviations.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Ethanol, 2-(octylthio)-

IUPAC Name:

Ethanol, 2-(octylthio)-

Constituent 2

Reference substance name:

2-(octylthio)ethanol

EC Number:

222-598-4

EC Name:

2-(octylthio)ethanol

Cas Number:

3547-33-9

Molecular formula:

C10H22OS

IUPAC Name:

2-(octylsulfanyl)ethan-1-ol

Constituent 3

Reference substance name:

Hydroxyethyl octyl sulfide

IUPAC Name:

Hydroxyethyl octyl sulfide

Details on test material:

- Name of test material (as cited in study report): 2-hydroxyethyl-n-octyl sulfide
- Molecular formula (if other than submission substance): not applicable
- Molecular weight (if other than submission substance): not applicable
- Smiles notation (if other than submission substance): not applicable
- InChl (if other than submission substance): not applicable
- Structural formula attached as image file (if other than submission substance): not applicable
- Substance type: no data
- Physical state: liquid
- Analytical purity: 96%
- Impurities (identity and concentrations): no data
- Composition of test material, percentage of components: no data
- Isomers composition: no data
- Purity test date: not applicable
- Lot/batch No.: 90ATHEN02
- Expiration date of the lot/batch: no data
- Radiochemical purity (if radiolabelling): not applicable
- Specific activity (if radiolabelling): not applicable
- Locations of the label (if radiolabelling): not applicable
- Expiration date of radiochemical substance (if radiolabelling): not applicable
- Stability under test conditions: no data
- Storage condition of test material: ambient conditions in the dark
- Other: no data

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Activated sludge was collected from the Cambridge Wastewater Treatment Facility (Cambridge, MD), which treats predominantly residential wastes.
- Laboratory culture: no
- Method of cultivation: not applicable
- Storage conditions: aerated until use
- Storage length: no data
- Preparation of inoculum for exposure: The sludge was adjusted to approx. 1000 mg total suspended solids/L with mineral media.
- Pretreatment: no
- Concentration of sludge: adjusted to approx. 1000 mg TSS/L
- Initial cell/biomass concentration: no data
- Water filtered: yes
- Type and size of filter used, if any: 2 mm screen
- The results of the standard plate count and TSS measurement performed on the inoculum were 5.3 x 104 CFU/mL and 973 mg/L, respectively.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

10 mg/L

Based on:

other: TOC

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Remarks:

: inorganic C analysis of CO2 in trapping solution

Details on study design:

TEST CONDITIONS
- Composition of medium: The test medium was a modified biochemical oxygen demand (BOD) test dilution water and was prepared using high quality water. All chemicals and reagents used in the preparation of the test medium were reagent grade or better. The following was added to each test chamber: 1) 2470 mL of NANO® pure water; 2) 3 mL calcium chloride solution (2.75%), 3 mL of ferric chloride solution (0.025%), 3 mL of magnesium sulfate solution (2.25%), 30 mL of phosphate buffer (pH 7.4); and 3) a volume of the activated sludge inoculum.
- Additional substrate: none
- Solubilising agent (type and concentration if used): none
- Test temperature: 20 ± 1 deg C
- pH: 7.4
- pH adjusted: no data
- CEC (meq/100 g): no data
- Aeration of dilution water: All chambers were aerated with CO2 free air for approximately 24 hours at a rate of 50 to 100 mL per minute to purge the systems of CO2.
- Suspended solids concentration: approx. 30 mg/L
- Continuous darkness: no data
- Other: An additional set of gas washing bottles that were not connected to a chamber were maintained concurrently with the traps connected to the chambers. These bottles contained approximately 100 mL of 0.5 N KOH and the amount of CO2 detected in the KOH solution was subtracted from the CO2 in the blank control traps to determine the amount of CO2 produced by the inoculum in the blank control. Magnetic stir bars and stir plates were used to mix the contents of the test chambers.

TEST SYSTEM
- Culturing apparatus: 4-L bottles
- Number of culture flasks/concentration: 3
- Method used to create aerobic conditions: CO2 free air was supplied to the test chambers
- Method used to create anaerobic conditions: not applicable
- Measuring equipment: Evolved CO2 within the test chamber was trapped as K2CO3 in the KOH solution and the amount of inorganic carbon in the trapping solution was measured at various intervals during the study, using a Shimadzu Model TOC-VCSH carbon analyzer.
- Test performed in closed vessels due to significant volatility of test substance: no
- Test performed in open system: no
- Details of trap for CO2 and volatile organics if used: After the aeration period the flow of CO2-free air was stopped and three CO2 traps, each containing approximately 100 mL of 0.5 N KOH, were connected to the exit air lines of each chamber.
- Other: no data

SAMPLING
- Sampling frequency: Days 2, 5, 8, 12, 15, 19, 22 and 26 (and 1 day after the test had been terminated on Day 29)
- Sampling method: The CO2 trap nearest the test chamber was removed and analyzed for inorganic carbon. The two remaining traps were placed one position closer to the test chamber and a new trap was placed on the end of the series. On the 28th day of the test, an aliquot of the contents of each test chamber was removed and the pH determined. The contents of all chambers were then acidified by the addition of 3 mL of concentrated hydrochloric acid to drive off inorganic carbonate. All chambers were aerated overnight and then a sample from each test chamber was removed for dissolved organic carbon (DOC) analysis and the trapping solutions closest to the test chambers were analyzed for inorganic carbon. Due to the low water solubility of the test substance, the ratio of total carbon to inorganic carbon was not measured at the beginning of the test.
- Sterility check if applicable: no
- Sample storage before analysis: no data
- Other: no data

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes (tested in triplicate)
- Abiotic sterile control: none
- Toxicity control: none
- Other: Sodium benzoate was tested as a reference substance in triplicate at a nominal concentration of 10 mg C/L.

STATISTICAL METHODS:
- No statistical evaluations performed

Reference substance

Reference substance:

other: sodium benzoate

Results and discussion

Preliminary study:

None

Test performance:

- No testing parameters/conditions were determined to have any affect on the study results.

% Degradation

Parameter:

other: of theorectical CO2

Value:

99.8

St. dev.:

5.2

Sampling time:

28 d

Remarks on result:

other: The average final pH was 6.8.

Details on results:

- The control chambers evolved an average of 72.2 mg CO2 over the test period. This value has been corrected for the amount of CO2 in the trapping solution since potassium hydroxide solution, even when freshly prepared, contains carbonates.
- The viability of the inoculum and validity of the test were supported by the results of the reference substance, sodium benzoate, from which an average of 102.2% of theoretical CO2 was evolved. An average percent biodegradation of greater than 60% was achieved by Day 8, thereby fulfilling the criteria for a valid test by reaching the pass level by Day 14.

Any other information on results incl. tables

Cumulative Percent of Theoretical Carbon Dioxide Evolved
Date	Day	Rep. 1	Rep. 2	Rep. 3
29-May-09	2	-0.7	-0.6	0.9
01-Jun-09	5	-5.2	-2.8	1.3
04-Jun-09	8	11.0	11.2	15.5
08-Jun-09	12	46.3	49.5	62.5
11-Jun-09	15	67.7	70.7	90.3
15-Jun-09	19	84.7	88.3	91.1
18-Jun-09	22	86.2	93.6	91.4
22-Jun-09	26	89.8	102.0	97.7
25-Jun-09	29	93.9	103.9	101.7
Cumulative Average (N=3)			99.8
Std. Dev.			5.2

 

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

: the total CO2 evolution for the inoculum blank was < 40 g/L

Interpretation of results:

readily biodegradable

Conclusions:

The final mean percent biodegradation for 2-hydroxyethyl-N-octyl sulfide (CAS No.: 3547-33-9) was 99.8% at 28 days with >60% degradation reached within 10 days of acheiving 10% of ThCO2.; therefore, the test substance may be considered readily biodegradable.