Reaction mass of methyl 2-methylbenzene-1-sulfonate and methyl toluene-4-sulphonate

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Type: mixed population of aquatic microorganisms
- Origin: secondary effluent of a wastewater treatment plant treating predominantly domestic sewage (Wupper area water authority, WWTP Odenthal)
- Date of collection: 2017-07-24
- Pre-treatment: separation of coarse particles by filtration, aeration of the resulting inoculum for 1 day

Duration of test (contact time):

28 d

Initial conc.:

5 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Pre-treatment of the test item
- 5.8 mg of the test item were weighed out and added to the test flasks, filled with ca. 300 mL of mineral medium
- inoculum was added
- flasks volume was made up to 1.16 L with mineral medium
- flasks were closed free from air bubbles with glass stoppers.
- initial concentration of test item: 5.0 mg/L (5.8 mg/1.16 L)

Pre-treatment of the reference compound
Reference compound name: sodium benzoate (Acros Organics)
- 500.2 mg sodium benzoate were added to 0.5 litres of deionised water and stirred for 24 hours on a magnetic stirrer
- 3.4 mL of the stock solution were given to the test flasks and filled with ca. 300 mL of mineral medium
- inoculum was added
- flasks volume was made up to 1.16 L with mineral medium
- flasks were closed free from air bubbles with glass stoppers.
- Concentration of stock solution: 1 g/L
- pH value of the stock solution: 7.4
- initial concentration reference compound: 2.9 mg/L (3.4 mg/1.16 L)

Pre-treatment of the toxicity control
- 5.8 mg of the test item were weighed and added to the test flasks, filled with ca. 300 mL of mineral medium
- 3.4 mL of the reference compound stock solution was added
- inoculum was added
- flasks volume was made up to 1.16 L with mineral medium
- the flasks were closed free from air bubbles with glass stoppers.
- initial concentration of test item: 5.0 mg/L (5.8 mg/1.16 L)
- initial concentration reference compound: 2.9 mg/L (3.4 mg/1.16 L)

Exposure conditions
- Test volume: 1.16 L
- Incubation time: 28 days
- Incubation temperature: 22 ± 2 °C

Reference substance:

benzoic acid, sodium salt

Remarks:

Acros Organics, purity 99.9 %, batch no. A0357641

Key result

Parameter:

% degradation (O2 consumption)

Value:

48

Sampling time:

28 d

Details on results:

15 % degradation after 7 d
36 % degradation after 14 d
51 % degradation after 21 d

Results with reference substance:

The reference compound sodium benzoate showed 81 % degradation after 14 days.

Validity criteria fulfilled:

yes

Remarks:

oxygen depletion in blank control <= 1.5 mg dissolved O2/L after 28 d; reference compound ≥ 60 % for ready biodegradability in 14 d; toxicity control > 25 % degradation in 14 d

Interpretation of results:

not readily biodegradable

Conclusions:

Within 28 days, a degradation of 48 % was determined for the test substance. Thus, it is considered to be not readily biodegradable.

Executive summary:

A study was performed to assess the ready biodegradability in accordance with the Council Regulation (EC) 440/2008 Method C.4-E “Closed Bottle Test” (2008). This test method is in all essential parts identical with OECD Guideline 301 D (adopted July 1992). The test substance was inoculated with secondary effluent to result in completely filled, closed flasks and incubated under aerobic conditions in the dark at 22 +- 2 °C for 28 days. During this period, the biodegradation was followed by analysis of dissolved oxygen. The amount of oxygen taken up by the test chemical, corrected for uptake by the blank inoculum run in parallel, was expressed as a percentage of theoretical oxygen demand (ThOD). Flasks with reference control, inoculum blank and toxicity control were run in parallel.

A degradation of 48 % was determined after 28 d. Therefore, the test substance is considered to be “Not Readily Biodegradable“.

The reference compound sodium benzoate showed 81 % degradation after 14 days.

Description of key information

A study was performed to assess the ready biodegradability in accordance with the Council Regulation (EC) 440/2008 Method C.4-E “Closed Bottle Test” (2008), which is in all essential parts identical with OECD Guideline 301 D (adopted July 1992).The test substance was inoculated and incubated under aerobic conditions in the dark at 22 +- 2 °C for 28 days. During this period, the biodegradation was followed by analysis of dissolved oxygen. Flasks with reference control, inoculum blank and toxicity control were run in parallel.

A degradation of 48 % was determined after 28 d. Therefore, the test substance is considered to be “Not Readily Biodegradable“.

The reference compound sodium benzoate showed 81 % degradation after 14 days.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed