7-amino-4-hydroxy-3-[[4-[(4-sulphophenyl)azo]phenyl]azo]naphthalene-2-sulphonic acid, compound with 2,2',2''-nitrilotriethanol (1:2)

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:

2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Qualifier:

according to guideline

Guideline:

other: Real Decreto 363/1995 (BOE núm. 133 de Junio de 1995

GLP compliance:

no

Vehicle:

no

Details on test solutions:

Taking into account the value of 90% of active material, the tests will be carried out with the 100% active material of the test material.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: Urban Water Treatment Plant in Manresa (Spain)
- Preparation of inoculum for exposure: The dry weight of the activated sludge from the urban sewage treatment plant (7.2 g /L) is calculated and suspended in water to a concentration of 4 g/L of suspended matter, so that when added 200 ml of these suspended sludge yields a final concentration of 1.6 g / L.
- Initial biomass concentration: Concentration of activated sludge (solids in suspension per liter): 1.6 g / L

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20 ± 2 ºC

pH:

7-8

Dissolved oxygen:

see tables

Nominal and measured concentrations:

10 mg/L, 32 mg/L, 100 mg/L, 320 mg/L and 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: beaker
- Material, size, headspace, fill volume: 500 mL
- Aeration: continuos, approximate flow of 1 liter / minute
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2
- Sludge concentration (weight of dry solids per volume): 1.6 g/L
- Nutrients provided for bacteria: synthetic residual water
- Nitrification inhibitor used (delete if not applicable): not specified
- Biomass loading rate:
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Composición Agua residual sintética (OCDE 209): Peptone 16 g; Meat extract 11 g; Urea 3 g; NaCl 0,7 g; CaCl2 2H2O 0,4 g; MgSO4 7H2O 0,2 g; K2HPO4 2,8 g diluted to 1000 mL with deionized water.
- Particulate matter: --
OTHER TEST CONDITIONS
- Adjustment of pH: not specified
- Photoperiod: not specified
- Light intensity: not specified
- Details on termination of incubation: not specified
EFFECT PARAMETERS MEASURED (with observation intervals if applicable): respiration inhibition

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

338 mg/L

Nominal / measured:

estimated

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Results with reference substance (positive control):

- Results with reference substance valid? yes, in the interval beteen 5mg/L and 30 mg/L, accepted range specified in the guideline OCDE 209
- Relevant effect levels: CE50 h = 14 mg/L

Table 1. pH values at the beginning of the study

concentration	control	10	32	100	320	1000	control
pH	7.36	7.36	7.36	7.35	7.29	7.17	7.36

Table 2. Oxygen measurements (mg/L) during the respiration inhibition test. Values were collected at 1 minute intervals

conc. mg/L	mg O2/L in the time interval (minutes)
--	0	1	2	3	4	5	6	7	8	9	10
control	6.26	5.89	5.52	5.19	4.84	4.46	4.09	3.68	3.24	2.91	2.64
10	6.28	5.91	5.51	5.09	4.69	4.28	3.89	3.50	3.08	3.69	2.29
32	6.32	5.98	5.62	5.26	4.89	4.53	4.15	3.75	3.35	3.01	2.78
100	6.29	5.98	3.66	5.36	5.03	4.71	4.42	4.09	3.79	3.48	3.15
320	6.33	6.14	5.94	5.73	5.52	5.32	5.13	4.92	4.71	4.52	4.31
1000	6.28	6.22	6.15	6.08	5.99	5.93	5.85	5.78	5.70	5.64	5.56
control	6.28	5.91	5.53	5.21	4.83	4.42	4.05	3.65	3.19	2.88	2.59

Table 3. Respiration rate (mg L-1 h-1) obtained at each of the concentrations and controls

	control	10	32	100	320	1000	control
respiration rate mg/L.h	21.72	23.94	21.24	18.84	12.12	4.32	22.14

Table 4. % respiration inhibition (3h)

Conc. (mg/L)	% respiration inhibition (3h)
control	0
10	0
32	3
100	14
320	45
1000	80

Validity criteria fulfilled:

yes

Conclusions:

The result obtained in this study indicates that the test substance has a EC50(3h) of 338 mg/L.

Executive summary:

The study of bacterial inhibition in activated sludge of the test substance was carried out, following the OECD Guideline 209 (1984) and Royal Decree 363/1995 (BOE No. 133 of June 1995).
This method is used to evaluate the effect of the test substance on microorganisms by measuring the respiration rate under certain conditions and in the presence of different concentrations of the substance
Activated sludge from an urban sewage treatment plant has been subjected to the dye at the test concentrations: 10, 32, 100, 320 and 1000 mg / L of active substance. The total duration of the test was 3 hours.
The result obtained in this study indicates that the test substance presents a value of EC50 (3h) equal to 338 mg / L of active material.

Description of key information

The toxicity to aquatic microorganisms is determined by means of one test conducted on the substance Direct Red 254 TEA salt (CAS 64683-40 -5) according to OECD Guideline 209 that results on one EC50 338 mg/L value.

Based on the EC value obtained and considering the existing information, the substance is not harmful to microorganisms.

Key value for chemical safety assessment

EC50 for microorganisms:

338 mg/L