Sodium [[α,α'-(ethylenediimino)bis[2-hydroxybenzene-1-acetato]](4-)]ferrate(1-)

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 - 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:

Details on properties of test surrogate or analogue material (migrated information):
No surrogate or analogue material was used.

Analytical monitoring:

not required

Details on sampling:

Not applicable.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Test substance: 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 1 L with demineralized water. The stock solution appeared red brown and dissolved.

- 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 1 L with demineralized water. The stock solution appeared dissolved and yellowish.

Test organisms (species):

activated sludge

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.
- Source: municipal wastewater treatment plant of Mannheim, Germany; from the aeration tank of the plant

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

No post exposure observation period described.

Hardness:

Not applicable.

Test temperature:

20 +/- 2 °C

pH:

7.15

Dissolved oxygen:

No details available.

Salinity:

Not applicable.

Nominal and measured concentrations:

Test substance: 1000, 500, 250, 125 and 62.5 mg/L (nominal)
Reference substance: 1, 10 and 100 mg/L (nominal)

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

TEST PROCEDURE:
Aliquots of the stock solutions with test- or reference item were pipetted into test vessels and made up with demineralized water to a volume of 150 mL. After that 8 mL synthetic medium were given to the test vessel. To prepare the blank control assays, 150 mL of demineralized water and 8 mL synthetic medium were given to the blank control test vessels. The pH-values were measured in all test vessels. An adjustment was not necessary. 42 mL demineralized water were added to each test vessel. After addition of 50 mL of the inoculum suspension (dry weight 7.5 g/L) the incubation was started by aeration of the test vessels with pressure air. The vessels for the blank control assays were prepared according to the same procedure without addition of test- or reference item. After 180 minutes incubation the mixtures in the test vessels were placed subsequently into a closed oxygen measuring cell. A chart recorder recorded the oxygen respiration rates. The oxygen consumption of the blank control BC1 was measured first. The oxygen consumption of the reference item assays (RS) and the test item assays was measured in the sequence RS1, RS2, RS3; TS1, TS2, TS3, TS4 and TS5.
The oxygen consumption of the blank control BC2 was measured at last.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

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

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

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

Details on results:

No further details are available.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: up to 80 % inhibition occurred

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 accuracy of 2 significant digits.
The degree of inhibition (EC20; EC50 and EC80) of the reference item was also 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

Remarks:

Validity criteria of the applied guideline were fulfilled.

Conclusions:

The study is regarded as a valid guideline study conducted under certificated GLP compliance. According to the reported EC50 value (> 1000 mg/L, nominal) the test substance is not acutely toxic towards aquatic microorganisms.

Executive summary:

The toxicity of Acetic acid, oxo-, sodium salt, reaction products with ethylenediamine and phenol, iron sodium salts (CAS 84539-55-9) towards freshwater microorganisms was investigated in accordance to OECD Guideline 209 / EU Method C11 (BASF SE, 2009). Activated sludge was collected from the aeration tank at a municipal wastewater treatment. Aliquots of the stock solutions with test- or reference substance were pipetted into test vessels and made up with demineralized water to a volume of 150 mL. After that 8 mL synthetic medium were given to the test vessel. To prepare the blank control assays 150 mL of demineralized water and 8 mL synthetic medium were given to the blank control test vessels. The pH-values were measured in all test vessels. An adjustment was not necessary. 42 mL demineralized water were added to each test vessel. After addition of 50 mL of the inoculum suspension (dry weight 7.5 g/L) the incubation was started by aeration of the test vessels with pressure air. The vessels for the blank control assays were prepared according to the same procedure without addition of test- or reference item. After 180 minutes incubation the mixtures in the test vessels were placed subsequently into a closed oxygen measuring cell. As results, an EC50(3h) and EC80(3h) > 1000 mg/L and an EC10(3h): 450 mg/L is reported.

Description of key information

EC10 (3h): 450 mg/L, EC50 (3h) > 1000 mg/L [OECD 209; activated sludge; read-across substance: Fe(Na)EDDHA]

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

450 mg/L

Additional information

Toxicological effects towards aquatic microorganisms of o-o-EDDHA (CAS16455-61-1) was not investigated experimentally. Read across to the structurally similar substance Fe(Na)EDDHA (CAS 84539-55-9) was performed to fulfill this relevant endpoint under REACH (for further details, please refer to the separate read-across statement).

The toxicity of Fe(Na)EDDHA (CAS 84539-55-9) towards freshwater microorganisms was investigated in accordance to OECD Guideline 209 / EU Method C11 (BASF SE, 2009). Activated sludge was collected from the aeration tank at a municipal waste water treatment. Aliquots of the stock solutions with test- or reference substance were pipetted into test vessels and made up with demineralized water to a volume of 150 mL. After that 8 mL synthetic medium were given to the test vessel. To prepare the blank control assays 150 mL of demineralized water and 8 mL synthetic medium were given to the blank control test vessels. The pH-values were measured in all test vessels. An adjustment was not necessary. 42 mL demineralized water were added to each test vessel. After addition of 50 mL of the inoculum suspension (dry weight 7.5 g/L) the incubation was started by aeration of the test vessels with pressure air. The vessels for the blank control assays were prepared according to the same procedure without addition of test- or reference item. After 180 minutes incubation the mixtures in the test vessels were placed subsequently into a closed oxygen measuring cell. As results, an EC50(3h) and EC80(3h) > 1000 mg/L and an EC10(3h): 450 mg/L is reported.