Calcium 4-[(5-chloro-4-methyl-2-sulphonatophenyl)azo]-3-hydroxy-2-naphthoate

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

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

GLP compliance:

yes

Specific details on test material used for the study:

- Storage condition of test material: at room teperature at about 20 °C, away from direct sunlight

Analytical monitoring:

no

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Preparation of inoculum for exposure: inoculum was washed twice with tap water by centrifugation and the supernantant liquid phase was decanted
- Initial biomass concentration: 3 g/L

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Test temperature:

20 °C

pH:

7.6 - 8.5

Dissolved oxygen:

8.1 - 9.1

Nominal and measured concentrations:

Nominal test concentrations: control, 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test media: 51 mg test substance, 16 mL synthetic wastewater, 200 mL activated sludge, 284 mL tap water
- Test vessel: glass beakers, 200 mL
- No. of vessels per concentration: 1
- No. of vessels per control: 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: tap water, synthetic wastewater
- Intervals of water quality measurement: pH and oxygen content

EFFECT PARAMETERS MEASURED: oxygen consumption

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

other: NOEC (EC15)

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Results with reference substance (positive control):

3-h EC50 = 14 mg/L

Validity criteria fulfilled:

yes

Conclusions:

The inhibition of the degradation activity of activated sludge is not anticipated when introduced to biological treatment plants in appropriate low concentrations.

Description of key information

The inhibition of the degradation activity of activated sludge is not anticipated when introduced to biological treatment plants in appropriate low concentrations.

Additional information

Changes in the respiration rate of activated sludge when exposed to the substance were investigated in a OECD 209 guideline study (RCC Ltd, 2007). The respiration of domestic activated sludge was monitored for 3 hours. The sludge bacteria were not affected by the substance. A NOEC of >= 100 mg/L was determined from this study.