Reaction mass of mixed xylenes and sulphur monochloride

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:

18th August 2015 - 16th September 2015

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Batch 46000058
- Purity test date: Not applicable; substance is a UVCB

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: Due to the low water solubility of the test item, the test item was dissolved in an auxillary solvent prior to adsorption onto filter paper. High shear mixing was then used to break up the filter paper containing the test item. This method is used to evenly distribute the test item through the test medium and increases the surface area of the test item thereby increasing any potential biodegradation.

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Duration of test (contact time):

ca. 28 d

Initial conc.:

ca. 14.7 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: As recommended by the OECD Guideline.
- Solubilising agent (type and concentration if used): Dissolution of the test item in acetone dispensed onto filter paper and evaporated to dryness. The filter paper was dispersed into the mineral medium using high shear mixing prior to the addition to the innoculated mineral medium.
- Test temperature: 22 - 24 oC
- pH: 7.8
- pH adjusted: yes to 7.6
- CEC (meq/100 g):
- Aeration of dilution water: Yes using CO2 free air.
- Continuous darkness: yes
- Suspended solids in inoculum: 3.6 g/L prior to use.


TEST SYSTEM
- Number of culture flasks/concentration: 1
- Method used to create aerobic conditions: Purge with CO2 free air.
- Details of trap for CO2 and volatile organics if used: Two 500ml Dreschel bottles containing 350mls of 0.05M NaOH.

SAMPLING
- Sampling frequency: Days 0, 2, 6, 8, 10, 14, 21, 28 and 29 for the first CO2 absorber. Days 0 and 29 for the second CO2 absorber.
- Sample storage before analysis: Samples analyzed by IC were not stored but analysed immediately.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes including filter paper
- Toxicity control: Yes including filter paper
- Test Item plus reference item including filter paper

STATISTICAL METHODS:
Student's t-test

Reference substance:

benzoic acid, sodium salt

Preliminary study:

Not appliacable

Key result

Parameter:

% degradation (CO2 evolution)

Value:

ca. 0

Sampling time:

28 d

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test item obtained 0% biodegradation after 28 days and cannot be considered readily biodegradable under the conditions of OECD Guideline No. 301B.

Executive summary:

The test item, reaction mass of mixed xylenes and sulphur monochloride (Batch 4600058) was tested for ready biodegradability in a GLP study using the CO₂Evolution Test as per OECD Guideline no. 301B. The test item was tested at the concentration of 14.7 mg/L (equivalent to 10 mg of TOC/L) along with procedural and toxicity controls. The CO₂ released was measured on the 2nd, 6th, 8th, 10th, 14th, 21st, 28th and 29th day after the initiation of the test. There was 74% degradation of the procedural control during the treatment period and 45 % degradation of the toxicity control. The test fulfilled all the validity criteria.

Based on the criteria for readily biodegradability (60% of biodegradation over 28 days within a 10 day period), the test item was considered as not readily biodegradable, as 0% degradation was achieved during the test period.

Description of key information

One key study is available performed in accordance with GLP and OECD Guideline 301B. The results show that no degradation was obtained over the 28 day period of the study.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed