Reaction mass of Cobaltate(3-), bis[2-[[[3-[2-[1-[[(2-chlorophenyl)amino]carbonyl]-2-(oxo-κO)propyl]diazenyl-κN1]-4-(hydroxy-κO)phenyl]sulfonyl]amino]benzoato(3-)]-, sodium (1:3) and tetrasodium bis[2-[[[3-[[1-[(2-chloroanilino)carbonyl]-2-oxopropyl]azo]-4-hydroxyphenyl]sulphonyl]amino]benzoato(3-)]cobaltate(4-)

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:

1993

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

yes

Remarks:

deionised water instead of distilled water for the stock solution, - Preparation of the inocu higher sludge weight after the washing procedure (Sludge concentrations in the test according to the guidelines), - 4 instead of 5 test concentrations.

Qualifier:

equivalent or similar to guideline

Guideline:

other: EG Method Nr. L 133/118 "Belebtschlamm: Prüfung der Atmungshemmung" (Ausgabe: 30.05.1988)

GLP compliance:

yes

Specific details on test material used for the study:

Code number: 92368/A
EN/Batch: PLN 13
Purity: ca. 80 %
Appearance: solid
Solubility: miscible
Storage: room temperature
Expiration date: 03/98

Analytical monitoring:

not specified

Details on sampling:

no data

Vehicle:

no

Details on test solutions:

no data

Test organisms (species):

activated sludge

Details on inoculum:

- Source: Activated sludge of a communal sewage treatment plant (ARA-Birsig Therwil).
- Pretreatment: 3 times washing with tap water and addition of synthetic sewage (1 d before the main test).
- Initial biomass concentration: 1560 mg/L.

Test type:

not specified

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

no data

Hardness:

no data

Test temperature:

20.5 °C

pH:

7.2 before the test beginning

Dissolved oxygen:

no data

Salinity:

no data

Nominal and measured concentrations:

no data

Details on test conditions:

- Test concentrations: 320, 100, 32 and 10 mg/L

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol (three reference substance concentrations 32, 10 and 3.2 mg/L)

Key result

Duration:

3 h

Dose descriptor:

IC50

Effect conc.:

> 320 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

- Results with reference substance valid? Yes.
- Relevant effect levels: The IC50 (3 h) of the reference substance 3,5-Dichlorophenol: 8.8 mg/L.

Reported statistics and error estimates:

no data

Table 1 presenting inhibition results for test substance

Test substance (mg/L)	pH after 3h	O2-consumption (in cm)	time (in cm)	mg O2 pro min/L	% of control	% inhibition
320	7.5	2.2	4.7	0.37	53.62	46.38
100	7.7	2.9	4.5	0.52	75.36	24.64
32	7.7	2.8	3.5	0.64	92.75	7.25
10	7.7	3.5	4.2	0.67	97.10	2.90

Table 2 presenting inhibition results for positive control

3,5 -Dichlorophenol (mg/L)	pH after 3h	O2-consumption (in cm)	time (in cm)	mg O2 pro min/L	% of control	% inhibition
32	7.9	0.7	4.5	0.12	17.39	82.61
10	7.8	1.9	4.8	0.32	46.38	53.62
3.2	7.8	3.2	4.7	0.54	78.26	7.25

Validity criteria fulfilled:

yes

Conclusions:

The IC50 of the test substance was determined to be >320 mg/L.

Executive summary:

A study was conducted to assess the inhibitory effect of the test substance (of ca. 80 % purity) on the oxygen consumption rate of aerobic microorganisms (activated sludge) according to OECD Guideline 209 in compliance with GLP. A mixture of activated sludge from the domestic sewage and a range of concentrations of the test substance or the reference substance were incubated for a period of 3 h with continuous aeration. Test substance and reference substance 3,5-dichlorophenol were tested at nominal concentrations of 320, 100, 32 and 10 mg/L and 32, 10 and 3.2 mg/L, respectively. The respiration rate of each test concentration was calculated as a percentage of the mean of the two control respiration rates. The results were plotted on a logarithmic (concentration against % inhibition) graph, where the IC50 was evaluated. The reference substance yielded an IC50 value of 8.8 mg/L, which is within the prescribed range by guideline. Hence the validity criteria of the guideline were fulfilled. 46.38, 24.64, 7.25 and 2.90 % inhibitions were seen with 320, 100, 32 and 10 mg/L test concentrations respectively. Based on these findings, the IC50 of the test substance was determined to be >320 mg/L.

Description of key information

The IC50 to the bacterial population was determined to be 300 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

300 mg/L

Additional information

In the study (1993) conducted to assess the inhibitory effect of the test substance (of ca. 80 % purity) on the oxygen consumption rate of aerobic microorganisms (activated sludge) according to OECD Guideline 209 in compliance with GLP, the IC50 of the test substance was determined to be >320.0 mg/L. In another study conducted with methodology similar to OECD 209, the IC50 of FAT 20049/E was found to be 300 mg/L. Outcomes of the other supporting studies are presented below:

FAT 20049/D - 21d IC50 : 200 mg/L, 3h IC50: >100 mg/L

FAT 20049/A - 21 IC50: >300 mg/L