Reaction mass of Cobaltate(2-), [2-[[[4-hydroxy-3-[[2-oxo-1-[(phenylamino)carbonyl]propyl]azo]phenyl]sulfonyl]amino]benzoato(3-)][2-[[2-hydroxy-5-[(phenylamino)sulfonyl]phenyl]azo]-3-oxo-N-phenylbutanamidato(2-)]-, disodium and Cobaltate(3-), bis[2-[[[4-hydroxy-3-[[2-oxo-1-[(phenylamino)carbonyl]propyl]azo]phenyl]sulfonyl]amino]benzoato(3-)]-, trisodium and sodium bis[2-[[2-hydroxy-5-[(phenylamino)sulphonyl]phenyl]azo]-3-oxo-N-phenylbutyramidato(2-)]cobaltate(1-)

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

From October the 03rd to November the 26th, 1985

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

4 April 1984

GLP compliance:

yes

Details on test solutions:

The test solutions were prepared by adding the test material directly to the test water.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Source: ARA Birsig, Therwil, Switzerland.
- Treatment: the sludge is centrifuged and washed three times with drinking water; then suspended in water with a solids content of 4 g/l and after the addition of 20 ml synthetic sewage aerated overnight at 20 °C.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20 ± 2 °C

Nominal and measured concentrations:

100, 180, 320., 560, 1000 mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel: 1000 ml glass beaker with 500 ml test solution.
- Aeration: air flow 0.5 to 1 l/min
- No. of vessels per concentration: 1 replicate.
- No. of vessels per control: 2 replicates.
- Sludge concentration: 1.6 g/l.

TEST MEDIUM / WATER PARAMETERS
- Preparation of dilution water:
carbon filtered drinking water with a total hardness of about 180 mg CaCO3/l and pH 7.6 to 8.0.

MEASURING APPARATUS
500 ml flat bottomed flask, totally filled with test solution.

EFFECT PARAMETERS MEASURED
The percentage inhibition of respiration was plotted against concentration on logarithmic probability paper. The EC50, EC20 and EC50 were calculated with normal statistical procedures (Regression line).

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

115.9 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

EC20 (3h): 30.3 mg/l (estimated, nominal conc.)
EC80 (3h): 443.6 mg/l (estimated, nominal conc.)

Results with reference substance (positive control):

EC50 (3h): 7.3 mg/l

Rate of respiration inhibition

Nominal conc. (mg/l)	Oxygen consumption (mg O2/l/min)	% inhibition
Control 1	0.789
Control 2	0.806
Mean controls	0.797	-
100	0.458	42.5
180	0.304	61.8
320	0.169	78.8
560	0.131	83.6
1000	0.081	89.8

Calculation of the regression line

y (% inhibition)	Probits	x (conc. mg/l)	log x
42.5	4.8109	100	2
61.8	5.3002	180	2.2553
78.8	5.7995	320	2.5051
83.6	5.9782	560	2.7482
89.8	6.2702	1000	3

Conclusions:

EC50 (3h): 116 mg/l (estimated, nominal conc.)

Executive summary:

The test material was tested in accordance with the OECD Guideline 209 to investigate the potential toxicity to microorganisms (Activated Sludge, Respiration Inhibition Test). The nominal concentrations were used: 100, 180, 320., 560, 1000 mg/l.

The percentage inhibition of respiration was plotted against concentration on logarithmic probability paper. The EC50, EC20 and EC50 were calculated with normal statistical procedures (Regression line).

The EC20 (3h) was estimated to be 30.3 mg/l, while the EC80 (3h) was estimated to be 443.6 mg/l.

Conclusion

EC50 (3h): 116 mg/l (estimated, nominal conc.)

Description of key information

EC50 (3h): 116 mg/l (estimated, nominal conc.)

Key value for chemical safety assessment

EC50 for microorganisms:

116 mg/L

Additional information

The test material was tested in accordance with the OECD Guideline 209 to investigate the potential toxicity to microorganisms (Activated Sludge, Respiration Inhibition Test). The nominal concentrations were used: 100, 180, 320., 560, 1000 mg/l. The percentage inhibition of respiration was plotted against concentration on logarithmic probability paper. The EC50, EC20 and EC50 were calculated with normal statistical procedures (Regression line).

The EC20 (3h) was estimated to be 30.3 mg/l, while the EC80 (3h) was estimated to be 443.6 mg/l. The EC50 (3h) vales was estimated to be 116 mg/l.