Sulfonic acids, C14-18-alkane hydroxy and C12-20-alkapolyene and C14-18-alkene and C12-20-alkene hydroxy, sodium salts

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:

29 August 2017 - 22 November 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

The activated sewage sludge sample was washed twice by settlement and re-suspension in mineral medium to remove any excessive amounts of dissolved organic carbon (DOC) that may have been present. The washed sample was then maintained on continuous aeration in the laboratory at a temperature of approximately 21 ºC and used on the day of collection. Determination of the suspended solids level of the activated sewage sludge was carried out by filtering a sample (100 mL) of the washed activated sewage sludge by suction through pre-weighed GF/A filter paper using a Buchner funnel. Filtration was then continued for a further 3 minutes after rinsing the filter three successive times with 10 mL of deionized reverse osmosis water. The filter paper was then dried in an oven at approximately 105 ºC for at least 1-Hour and allowed to cool before weighing. This process was repeated until a constant weight was attained. The suspended solids concentration was equal to 2.4 g/L prior to use.

Initial conc.:

ca. 10 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Test temperature: between 22 °C and 24 °C
- pH: 7.4 ± 0.2
- pH adjusted: yes
- Aeration of dilution water: CO2-free air bubbled through the solution at a rate of 30 to 100 mL/min per vessel
- Suspended solids concentration: 30 mg suspended solids (ss)/L
- Continuous darkness: yes


TEST SYSTEM
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: CO2-free air bubbled through the solution at a rate of 30 to 100 mL/min per vessel
- Measuring equipment: TOC analyser
- Test performed in open system: No
- Details of trap for CO2: The CO2 produced by degradation was collected in two 500 mL Dreschel bottles containing 350 mL of 0.05 M NaOH. The CO2 absorbing solutions were prepared using purified water.


SAMPLING
- Sampling frequency: Days 0, 2, 6, 8, 10, 14, 21, 28 and 29
- Sampling method: Samples (2 mL) were taken from the first CO2 absorber vessels on Days 0, 2, 6, 8, 10, 14, 21, 28 and 29. The second absorber vessels were sampled on Days 0 and 29.
- Sample storage before analysis: not applicable

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

Reference substance:

benzoic acid, sodium salt

Preliminary study:

The results obtained from the samples taken for DOC analysis from the preliminary investigational work indicated that the test item did not adsorb to filter matrices or to activated sewage sludge. Therefore, for the purpose of the study, the samples taken for DOC analysis were filtered to remove the suspended solids present without the loss of any test item.

Test performance:

The total CO2 evolution in the inoculum control vessels on Day 28 was 39.06 mg/L and therefore satisfied the validation criterion given in the OECD Test Guidelines.

Key result

Parameter:

% degradation (CO2 evolution)

Value:

ca. 110

Sampling time:

28 d

Details on results:

Biodegradation values in excess of 100% were considered to be due to an increase in the numbers of viable micro-organisms in the test item vessels as a result of the readily biodegradable nature of the test item. This effect occurs due to the micro-organisms utilizing the test item as a carbon source for cellular growth resulting in a greater number of viable micro-organisms in these vessels when compared to the control vessels. The increased number of micro-organisms in these vessels gave rise to increased respiration rates and hence background CO2 evolution was greater than in the control vessels. This increase in background CO2 evolution resulted in biodegradation rates in excess of 100%.

Results with reference substance:

Sodium benzoate attained 74% biodegradation after 14 days and 102% biodegradation after 28 days thereby confirming the suitability of the inoculum and test conditions. Biodegradation values in excess of 100% were considered to be due to sampling/analytical variation.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test item attained 110% biodegradation after 28 days and satisfied the 10-Day window validation criterion, whereby 60% biodegradation must be attained within 10 days of the biodegradation exceeding 10%.
The test item can therefore be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301B.

Description of key information

A ready biodegradability screening test was conducted (Envigo Research Limited, 2018) to assess the potential for Sulfonic acids, C14-18-alkane hydroxy and C12-20-alkapolyene and C14-18-alkene and C12-20-alkene hydroxy, sodium salts to be degradaed by microorganisms over a 28 -day period. The study was performed according to OECD Guidelines for Testing of Chemicals (1992) No. 301B, "Ready Biodegradability; CO2 Evolution Test" referenced as Method C.4-C of Commission Regulation (EC) No. 440/2008 and US EPA Fate, Transport, and Transformation Test Guidelines OCSPP 835.3110 (Paragraph (m)), and in compliance with GLP.

Sulfonic acids, C14-18-alkane hydroxy and C12-20-alkapolyene and C14-18-alkene and C12-20-alkene hydroxy, sodium salts attained 110% biodegradation after 28 days and satisfied the 10-Day window validation criterion and so C14-18-alkane hydroxy and C12-20-alkapolyene and C14-18-alkene and C12-20-alkene hydroxy, sodium salts was concluded not to be readily biodegradable under the test conditions.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The test item attained 110% biodegradation after 28 days and satisfied the 10-Day window validation criterion. The test item can therefore be considered to be readily biodegradable

Biodegradation values in excess of 100% were considered to be due to an increase in the numbers of viable micro-organisms in the test item vessels as a result of the readily biodegradable nature of the test item. This effect occurs due to the micro-organisms utilizing the test item as a carbon source for cellular growth resulting in a greater number of viable micro-organisms in these vessels when compared to the control vessels. The increased number of micro-organisms in these vessels gave rise to increased respiration rates and hence background CO2 evolution was greater than in the control vessels. This increase in background CO2 evolution resulted in biodegradation rates in excess of 100%.