Sodium 1-amino-9,10-dihydro-9,10-dioxo-4-[(2,2,4-trimethylcyclohexyl)amino]anthracene-2-sulphonate

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:

From April 06th to September 27th, 1989

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

adopted April 4, 1984

Deviations:

yes

Remarks:

less concentrations were run

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

The test was run with aerobic activated sludge from a domestlc waste-water treatment plant (ARA, Sissach/Switzerland).

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

pH:

Control: 7.7- 7.8 (start)
Test vessels: 7.7 (start)

Nominal and measured concentrations:

Nominal 10 and 100 mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel: glass-flask (> 500 ml).
- Aeration: flasks were aerated with 0.2 l/minute instead of 0.5 l/minute to prevent foam development.
- No. of vessels per concentration: 1 replicate.
- No. of vessels per control: 2 replicates.
- No. of vessels per positive control: 1 replicate.

MEASUREMENTS
After 180 ninutes of aeration, the flrst sample was taken for oxygen measurement over a period of 10 minutes. Thereafter, in 15 minutes intervals, the rest of the samples were submitted to measurement of oxygen concentration.
Sampling was started wlth the control 1; thereafter, the oxygen consumptlin of the positive control, the test article samples and of control 2 was determined.

DETERMINATION OF OXYGEN CONCENTRATION
Oxygen consumption was measured over a period of 10 minutes. During measurement, the sample was not aerated but continuously stirred on a magnetic stirrer.

EFFECT PARAMETERS MEASURED
The inhibitory effect of the test article on the respiration rate (oxygen consumption per minute) is expressed as percentage of the mean of the two control respiration rates.

VALIDITY OF THE TEST
The tests are validated by testing a known standard, i.e. 3,5-dichlorophenol. The IC50 value should be in the range of about 5 - 30 mg/l.
Furthernore, the variation between the two control samples (start, end) should not be greater than 15 %.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol sodium salt (conc. 3.2, 10 and 50 mg/l)

Duration:

3 h

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:

Due to aeration of the test medium wlth test article, a foamy solution was obtained, where mainly the foam was coloured. Under these conditions the respiration rate of the sludge was moderately inhibited (37.3 %) at the highest concentration of 100 mg/l.

Results with reference substance (positive control):

The respiration rate was slightly inhibited (12.4 %) at a concentration of 3.2 mg/l. The IC50 was found to be about 8.3 mg/l after 3 hours of exposure.

Influence of test item and reference substance on the oxygen consumption of activated sludge, after 3 hours of exposure

Concentration (mg/l)	Oxygen consumption (mgO2/l/min)	Inhibition (%)	Starting pH
Control	0.94	--	7.7
Control	1.07	--	7.8
Mean± s	1.01± 0.07
Test item 100	0.63	37.3	7.7
Test item 10	0.92	8.5	7.7
Reference substance 50	0.09	91.0	7.7
Reference substance 10	0.25	75.1	7.7
Reference substance 3.2	0.88	12.4	7.7

Conclusions:

IC50 (3h) > 100 mg/l (nominal)

Executive summary:

Acute toxicity to waste-water bacteria was investigated following the OECD 209 testing guideline. The method deternines the respiration rate (oxygen consumption) of an aerobic actlvated sludge fed with an excess but standard amount of biodegradable food as compared to the respiration rate obtained in an activated sludge run under identical conditions but containing the test chemical.

The nominal test concentrations applied were 10 and 100 mg/l.

Due to aeration of the test medium wlth test article, a foamy solution was obtained, where mainly the foam was coloured. Under these conditions the respiration rate of the sludge was moderately inhibited (37.3 %) at the highest concentration of 100 mg/l.

Conclusion

IC50 (3h) > 100 mg/l (nominal)

Description of key information

IC50 (3h) > 100 mg/l (nominal)

Additional information

Acute toxicity to waste-water bacteria was investigated following the OECD 209 testing guideline. Due to aeration of the test medium wlth test article, a foamy solution was obtained, where mainly the foam was coloured. Under the tested conditions, the respiration rate of the sludge was moderately inhibited (37.3 %) at the highest concentration of 100 mg/l.