1-phenylazo-2-naphthol

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

Justification for type of information:

Data is from experimental report.

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))

Principles of method if other than guideline:

This test specifies a method for assessing the inhibitory effect of a test substance on the oxygen consumption rate of aerobic micro-organisms (activated sludge) after short-term exposure (30 or 180 min). The test results are reported as effective concentrations which indicate a respiration inhibition of 20, 50, and 80 % (EC20,EC50, EC80) compared to a control assay without test substance . The EC20 is regarded as a limit value for possible toxic effects in wastewater treatment plants . The test concentration in biodegradation tests should not exceed the EC20.
The EC-values are based on added nominal concentrations and not on analytically determined values . The nominal concentrations which indicate a respiration inhibition of 20, 50 and 80 % can be taken from the graph of the inhibition curve .

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

- Name of test material: 1-phenylazo-2-naphthol (Sudan Orange 220)
- Molecular formula: C16 H12 N2 O
- Molecular weight: 248.284 g/mol
- Smiles notation: c12c(\N=N\c3ccccc3)c(ccc1cccc2)O
- InChl: 1S/C16H12N2O/c19-15-11-10-12-6-4-5-9-14(12)16(15)18-17-13-7-2-1-3-8-13/h1-11,19H/b18-17+
- Substance type: Organic
- Physical state: Solid

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 02-0103

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: ambient (RT)
- Stability under test conditions: The stability of the test substance under storage conditions over the test period was guaranteed by the sponsor, and the sponsor holds this responsibility .
- Instability against: temperature above 110 degC

OTHER SPECIFICS:
The identity of the test substance was confirmed by IR-spectroscopy.

Analytical monitoring:

no

Details on sampling:

Preparation of the stock solution of the test substance : none

Vehicle:

yes

Remarks:

deionized water

Details on test solutions:

The test substance was added in the required amount to the test vessel with about 180 ml deionized water.The mixture was stirred for 22 ± 2 hours to obtain an optimal solution . Then synthetic medium was added the pH-value was adjusted to 7,5 ± 0,5, the inoculum was added and the test started .

Test organisms (species):

activated sludge

Details on inoculum:

- Preparation of inoculum for exposure:The inoculum was washed, brought to a concentration of 5 g/I dry substance and aerated during the night . 50 mi were added to a total volume of 250 ml to obtain a concentration of 1 g/I dry substance in the test .

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

180 min

Hardness:

No data

Test temperature:

20 ± 2 'C

pH:

7.7

Dissolved oxygen:

> 6.5 mg/I

Salinity:

No data

Conductivity:

No data

Nominal and measured concentrations:

1,10,100,1000 mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer-vessel (nominal volume 250 ml)
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 250 ml
- Aeration: > 2,5 mg/I

- Biomass loading rate: 8 ml/vessel 100-fold concentrated OECD medium

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

180 min

Dose descriptor:

other: EC20

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Inhibition of Oxygen Consumption

Key result

Duration:

180 min

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Inhibition of Oxygen Consumption

Key result

Duration:

180 min

Dose descriptor:

other: EC80

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Inhibition of Oxygen Consumption

Details on results:

The EC20 in the activated sludge respiration inhibition test is >100 mg/l . Disturbances in the biodegradation process of activated sludge are not to be expected if the test substance is correctly introduced into adapted wastewater treatment plants at low concentrations .

EFFECTIVE CONCENTRATIONS EC VALUES:

Reference substance (RS)

After 180 minutes incubation time

	EC20 mg/l	EC50 mg/l	EC80 mg/l	Highest concentration tested (mg/1 )
Reference substance	about 1.6	about 6	about 75	100

 

Validity criteria fulfilled:

yes

Remarks:

Deviation of blank controls < 15 %:yes and EC50 of 3,5-dichlorophenol in the range of 5-30 mg/I:yes

Conclusions:

The Inhibition of Oxygen Consumption by Activated Sludge in the Activated Sludge Respiration Inhibition Test according to OECD Guideline 209 was determined for 1-phenylazo-2-naphthol (Sudan Orange 220). Based on the experiment the EC20, EC50 and EC80 was reported as >1000 mg/L in a 180 min. of exposure period on the basis of inhibition of oxygen consumption effect.

Executive summary:

The Inhibition of Oxygen Consumption by Activated Sludge in the Activated Sludge Respiration Inhibition Test according to OECD Guideline 209 was determined for 1-phenylazo-2-naphthol (Sudan Orange 220).

This test specifies a method for assessing the inhibitory effect of a test substance on the oxygen consumption rate of aerobic micro-organisms (activated sludge) after short-term exposure (30 or 180 min). The test results are reported as effective concentrations which indicate a respiration inhibition of 20, 50, and 80 % (EC20,EC50, EC80) compared to a control assay without test substance . The EC20 is regarded as a limit value for possible toxic effects in wastewater treatment plants . The test concentration in biodegradation tests should not exceed the EC20.The EC-values are based on added nominal concentrations and not on analytically determined values . The nominal concentrations which indicate a respiration inhibition of 20, 50 and 80 % can be taken from the graph of the inhibition curve .

The EC20 in the activated sludge respiration inhibition test is >100 mg/l . Disturbances in the biodegradation process of activated sludge are not to be expected if the test substance is correctly introduced into adapted wastewater treatment plants at low concentrations .

Thus, based on the experiment the EC20, EC50 and EC80 was reported as >1000 mg/L in a 180 min. of exposure period on the basis of inhibition of oxygen consumption effect.

Description of key information

The Inhibition of Oxygen Consumption by Activated Sludge in the Activated Sludge Respiration Inhibition Test according to OECD Guideline 209 was determined for 1-phenylazo-2-naphthol (Sudan Orange 220). Based on the experiment the EC20, EC50 and EC80 was reported as >1000 mg/L in a 180 min. of exposure period on the basis of inhibition of oxygen consumption effect.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

Additional information

The Inhibition of Oxygen Consumption by Activated Sludge in the Activated Sludge Respiration Inhibition Test according to OECD Guideline 209 was determined for 1-phenylazo-2-naphthol (Sudan Orange 220).

This test specifies a method for assessing the inhibitory effect of a test substance on the oxygen consumption rate of aerobic micro-organisms (activated sludge) after short-term exposure (30 or 180 min). The test results are reported as effective concentrations which indicate a respiration inhibition of 20, 50, and 80 % (EC20,EC50, EC80) compared to a control assay without test substance . The EC20 is regarded as a limit value for possible toxic effects in wastewater treatment plants . The test concentration in biodegradation tests should not exceed the EC20.The EC-values are based on added nominal concentrations and not on analytically determined values . The nominal concentrations which indicate a respiration inhibition of 20, 50 and 80 % can be taken from the graph of the inhibition curve.

The EC20 in the activated sludge respiration inhibition test is >100 mg/l . Disturbances in the biodegradation process of activated sludge are not to be expected if the test substance is correctly introduced into adapted wastewater treatment plants at low concentrations.

Thus, based on the experiment the EC20, EC50 and EC80 was reported as >1000 mg/L in a 180 min. of exposure period on the basis of inhibition of oxygen consumption effect.