Benzene, 1,1'-oxybis[methyl-, sulfonated, ammonium salts

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

20-21 June 1988

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Further details on test item are lacking.

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

1984

Qualifier:

according to guideline

Guideline:

other: "Proposed Method for the Determination of the Biodegradability of Surfactants used in Synthetic Detergents" (OECD Technical Report of June 11, 1976).

Version / remarks:

June 11, 1976

GLP compliance:

no

Specific details on test material used for the study:

Storage: At room temperature, in the dark

Details on sampling:

After 180 minutes of aeration, the first sample was taken for oxygen measurement over a period of up to 10 minutes. Thereafter, in 15 minutes intervals,
the rest of the samples were submitted to measurement of oxygen concentration.

Vehicle:

no

Details on test solutions:

- Test substance: 500 mg/l in distilled water
- Controls: 3,5-Dichlorophenol. 0.5 g in 10 ml 1N NaOH, dilurte to 30 ml with distilled water, neutralized with 1N H2SO4 and diluted to 1 L. Final pH: 7.9. Final concentration 500mg/l

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: domestic waste-water treatment plant (ARA, Sissach/Switzerland)
- Preparation of inoculum for exposure: The sludge was coarse sieved, centrifuged, the supernatant liquid phase decanted, the solid material resuspended in tap water and again centrifuged. This procedure was repeated further 2 times. A volume of of this washed sludge suspension corresponding to 4.0 g dry material was made up with Soerensen buffer (pH 7) to 1 L. To that mixture 50 ml OECD recommended synthetic sewage feed were added. Thereafter, the sludge was incubated overnigth at 20-25 °C under aereation.
- Initial biomass concentration: 4.0 g dry weight/l

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

180 min

pH:

7.8

Nominal and measured concentrations:

Nominal: 10 and 100 mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel: glass-flasks (>500 ml)
- Fill volume: 500 ml
- Aeration: 0.7 l/min
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2
- No. of vessels per positive control (replicates): 1
- Sludge concentration (weight of dry solids per volume): 4.0 g/l
OTHER TEST CONDITIONS
- Adjustment of pH: No
TEST CONCENTRATIONS
- Test concentrations: 10 and 100 mg/l

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol, 3.2, 10 and 50 mg/l

Key result

Duration:

180 min

Dose descriptor:

IC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

- Blank controls oxygen uptake rate: 0.36 +/- 0.02 mg O2/l min

Results with reference substance (positive control):

- Results with reference substance valid? yes IC50 should be 5-30 mg/l
- Relevant effect levels: IC 50: 8 mg/l

Chemical	Concentration (mg/l)	Oxygen consumption (mg O2/l min)	Inhibiton (%)
Control	0	0.34
Control	0	0.37
3,5-dichlorophenol	50	0.03	91.6
3,5-dichlorophenol	10	0.18	49.3
3,5-dichlorophenol	3.2	0.25	29.6
Test item	100	0.39	-9.9
Test item	10	0.38	-7.0

Validity criteria fulfilled:

yes

Conclusions:

The tests are regarded to be valid since the variance between the control samples was 5.6 %. Furthermore, it was shown that the inhibitory effect of 3,5-dichlorophenol was with 8 mg/l wlthin the range of the IC 50-value of 5 to 30 mg/l. The test item showed, under the same conditions, an IC 50-value of >=100 mg/l .
In conclusion, the test item was found to be non-toxic to waste-water bacteria.

Executive summary:

The inhìbitory effect of the test item on aerobic waste-water bacteria was investigated in a respiration test.

The test article showed no inhibition (-9.9 %) of the respiration rate up to a concentration of 100 mg/l.

The IC 50 was determined to be:

IC 50:>100 mg/l.

In conclusion, the test item was found to be non-toxic to waste-water bacteria.

The IC 50 for dichlorophenol tested under the same conditions was about 8 mg/l.

Description of key information

The tests are regarded to be valid since the variance between the control samples was 5.6 %. Furthermore, it was shown that the inhibitory effect of 3,5-dichlorophenol was with 8 mg/l wlthin the range of the IC 50-value of 5 to 30 mg/l. The test item showed, under the same conditions, an IC 50-value of  >=100 mg/l .

In conclusion, the test item was found to be non-toxic to waste-water bacteria.

Key value for chemical safety assessment

EC50 for microorganisms:

100 mg/L