Acetic acid, oxo-, sodium salt, reaction products with ethylenediamine and phenol, iron sodium salts

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:

2009-11-20 to 2010-01-08

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:

no

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

- Name of test material (as cited in study report): Acetic acid,oxo-,sodium salt (FeNaEDDHA)
- Physical state: Solid, red, dark
- Analytical purity: 100 % (UVCB)
- Lot/batch No.: 09226BR8
- Expiration date of the lot/batch: 07 Mar 2012
- Storage condition of test material: Ambient at room temperature under light exclusion

Analytical monitoring:

not required

Details on sampling:

Not Applicable

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Test item: 2.0 g of the test item was added to about 800 mL of demineralized water and stirred at room temperature until the test item was completely dissolved. After that the pH-value was measured (measured value = 8.4) and adjusted to 7.1 with 1 M sulfuric acid solution. The stock solution was made up to 1L with demineralized water. The stock solution appeared red brown and dissolved.

- Controls: Reference item:
0.5 g of the reference item was added to about 800 mL of demineralized water and stirred at room temperature until the reference item was completely dissolved. The pH value of the stock solution was measured and adjusted to 7.3 with 1 M sodium hydroxide solution. Following this the stock solution was made up to 1L with demineralized water. The stock solution appeared dissolved and yellowish.

Test organisms (species):

activated sludge of a predominantly industrial sewage, de-adapted

Details on inoculum:

- Preparation of inoculum for exposure: The activated sludge suspension was sieved with a fine woven mesh (mesh size about 1 mm). This suspension was pre-aerated over night at room temperature. At the next day the sludge suspension was washed with tap water one time. After that the suspension was adjusted to 7.5 g/L dry matter.
- Initial biomass concentration: An aliquot of this suspension was added to the test vessels to obtain a sludge concentration of 1.5 g/L dry substance.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

Not Applicable

Test temperature:

20 +/- 2 °C

pH:

7.15

Salinity:

Not Applicable

Nominal and measured concentrations:

Nominal: Test item concentrations: 1000, 500, 250, 125, 62.5 mg/L

Reference item: 3,5 dichlorophenol
Tested concentrations: 100, 10, 1 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer-vessel (nominal volume 250 mL)
- Aeration: yes
- No. of vessels per concentration (replicates): 1 (5 concentrations)
- No. of vessels per control (replicates): 3
- No. of vessels per vehicle control (replicates): 2


OTHER TEST CONDITIONS
- Adjustment of pH: not required


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Oxygen consumption

TEST CONCENTRATIONS
- Test concentrations: 1000, 500, 250, 125, 62.5 mg/L (nominal)

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

450 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: Not Applicable

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: Not Applicable

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: Not Applicable

Details on results:

see Table below at "Any other information on results incl tables"

Results with reference substance (positive control):

see Table below at "Any other information on results incl tables"

Reported statistics and error estimates:

In order to calculate the inhibition effects of the test item at a particular concentration, the respiration rate was expressed as percentage of the mean of the 2 control respiration rates.
The degree of inhibition (EC10 and EC20) of the test item was evaluated by Probit analysis according to Finney. The values were given with an accuray of 2 significant digits.
The degree of inhibition (EC20; EC50 and EC80) of the reference item was evaluated by Probit
analysis according to Finney.

Measured data of oxygen content of the test assays at the begin and end of the evaluation time:

Assay identification	BC1	BC2	RS1	RS2	RS3	TS1	TS2	TS3	TS4	TS5
O2-concencentration Start [mg/L]	8.0	8.0	8.4	8.7	9.1	8.2	8.3	8.5	7.8	7.6
O2 -concentration after 6 minutes [mg/L]	7.0	7.0	7.5	8.2	8.9	7.5	7.5	7.5	6.5	6.0
O2consumption rate [mg/L in 6 min]	1.0	1.0	0.9	0.5	0.2	0.7	0.8	1.0	1.3	1.6
O2-consumption rate [mg/Lxh]	10	10	9	5	2	7	8	10	13	16
Specific O2-consumption rate [mg O2/gxh]	7	7	6	3	1	5	5	7	9	11
RS/TSconcentrations[mg/L]	-		1	10	100	1000	500	250	125	62.4
Calculation of inhibition respiration[%]	-	-	10	50	80	30	20	0	-30	-60

Legend: TS = test item, RS = reference item, BC = blank control

Validity criteria fulfilled:

yes

Conclusions:

In conclusion the 3 hours EC10 value for Acetic acid, oxo-, sodium salt in the Activated Sludge Respiration Inhibition Test was 450 mg/L. The EC50 was > 1000 mg/L.

Executive summary:

The Inhibition of Oxygen Consumption of microbial-inoculum by Acetic acid, oxo-, sodium salt (FeNaEDDHA), compared to the blank was determined according to the OECD Guideline for Testing of Chemicals (1984) No 209 "Activated Sludge, Respiration Inhibition Test" and Commission Regulation (EC) No 440/2008 Part C.11:Biodegradation - Activated Sludge Respiration Inhibition.

Activated sludge from the municipal wastewater treatment plant was exposed to an aqueous solution of the test material at nominal concentrations of 1000, 500, 250, 125, 62.5 mg/L for a period of 3 hours at a temperature of approximately 20 +/- 2 degree C with the addition of a synthetic medium as a respiratory substrate. The rate of respiration was determined after 3 hours contact time and compared to data for the control and a reference material, 3,5-dichlorophenol.

In conclusion the 3 hours EC10 value for the test substance FeNaEDDHA in the Activated Sludge Respiration Inhibition Test was 450 mg/L. The EC50 was greater than 1000 mg/L.

Description of key information

EC10(3h) = 450 mg/L for respiration inhibition of activated sludge (OECD 209)

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

450 mg/L

Additional information

In a guideline study the inhibition of oxygen consumption of activated sludge by the test substance FeNaEDDHA was determined according to OECD guideline 209. The 3h-EC10 value for the test substance FeNaEDDHA in the activated sludge respiration inhibition test was 450 mg/L. The 3h-EC50 was greater than 1000 mg/L.