Hexaammonium wolframate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

2002-07-01 to 2002-07-02

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Well documented, scientifically sound study that was conducted in accordance with GLP and the Commission Directive 88/302/EEC. The test method was similar to OECD guideline 209. However, there were no details on the testing conditions. The reliability of this study for this substance tested is a K1, but in application of read-across to a different substance, ECHA's guidance specifies that the score can be a maximum of a K2.

Justification for type of information:

1. HYPOTHESIS FOR THE CATEGORY APPROACH: The hypothesis is that properties are likely to be similar or follow a similar pattern because of the presence of a common metal ion, in this case tungstate.
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES):
Source: Ammonium paratungstate
Target: Ammonium metatungstate
3. CATEGORY APPROACH JUSTIFICATION: See Annex 3 in CSR
4. DATA MATRIX: See Annex 3 in CSR

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Qualifier:

according to guideline

Guideline:

other: Commission Directive 88/302/EEC; Official Journal of the EC L133 Part C (1988)

Principles of method if other than guideline:

The method assesses the effect of a test substance on microorganisms by measuring the respiration rate under defined conditions in the presence of different concentrations of the test substance.

GLP compliance:

yes

Analytical monitoring:

no

Details on sampling:

- Concentrations: Test concentration of the activated sludge 360.0 mg/L suspended solids
- Sampling method: Direct weighing

Vehicle:

yes

Details on test solutions:

The test substance was added to about 130 mL deionized water and stirred overnight before testing (equilibration phase).

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Origin: aeration tank of waste water treatment plant treating predominantly domestic sewage (Wupper area water authority)
- Pretreatment: aeration of the activated sludge; daily feed with synthetic medium

Test type:

other: mixed population of aquatic organisms (activated sludge)

Water media type:

not specified

Limit test:

yes

Total exposure duration:

3 h

Remarks on exposure duration:

3 hours with permanent aeration

Post exposure observation period:

no data

Hardness:

no data

Test temperature:

20 +/- 2 °C

pH:

pH of the suspension before application: 7.1
7.4 - 7.6

Dissolved oxygen:

5.6 - 6.2

Salinity:

n/a

Nominal and measured concentrations:

Nominal concentrations: 100, 1000, 10000 mg/L

Details on test conditions:

no data

Reference substance (positive control):

yes

Remarks:

3.5-Dichlorophenol, mg/L

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

The test substance showed a 17.5% respiration inhibition of activated sludge at a test substance concentration of 10000 mg/L.

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels: See results below

Reported statistics and error estimates:

no data

Measured values of reference substance

	Test concentration (mg/L)	O2 start (mg O2/L)	O2 end (mg O2/L	Exposure time (min)	Temp. (C)	pH
Reference	5	6.4	4.8	4	20	7.7
substance	10	8.4	8.0	3	20	7.6
3.5 -Dichloro-phenol	20	9.0	8.7	3	20	7.6

Results for Reference Substance: 3.5 -Dichlorophenol

Test Concentration	Respiratory rate (mg/L.h)	Inhibition
5	24.0	25.0
10	8.0	75.0
20	6.0	81.3

Conclusions:

The method assessed the effect of a test substance on micoorganisms by measuring the respiration rate under defined conditions in the presence of different concentrations of the test substance. Ammoniumparawolframat-tetrahydrat showed 17.5% respiration inhibition of activated sludge at a testsubstance concentration of 10000 mg/L. The EC50 > 10000 mg/L.

Executive summary:

No microorganims toxicity data of sufficient quality were available specifically on ammonium metatungstate (target substance). However, microorganism toxicity data are available on ammonium paratungstate (source substance), which are used for read-across. Due to similar water solubility for the target substance compared to the source substance, the resulting read-across from the source substance to the target substance is appropriate to estimate of potential toxicity for this endpoint. For more details, refer to the read-across category approach description in the Category section of this IUCLID submission or Annex 3 of the CSR.

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

supporting study

Study period:

2008-09-18 to: 2009-03-13

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Well documented, scientifically sound study conducted in accordance to GLP and OECD Guideline 209 without deviation. he reliability of this study for this substance tested is a K1, but in application of read-across to a different substance, ECHA's guidance specifies that the score can be a maximum of a K2.

Justification for type of information:

1. HYPOTHESIS FOR THE CATEGORY APPROACH: The hypothesis is that properties are likely to be similar or follow a similar pattern because of the presence of a common metal ion, in this case tungstate.
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES):
Source: Sodium Tungstate
Target: Ammonium metatungstate
3. CATEGORY APPROACH JUSTIFICATION: See Annex 3 in CSR
4. DATA MATRIX: See Annex 3 in CSR

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
no data

Analytical monitoring:

no

Details on sampling:

- Concentrations: A stock solution of the test substance was prepared in reagent water at a concentration of 2.00 mg total product/mL. Stock solution volumes of 2.5, 8.0, 25, 80, and 250 mL were added to the 10, 32, 100, 320, and 1,000 mg total product/L test flasks, respectively, for the range finding test. Since there was no appreciable inhibition (eg >50%) up to a nominal of 1,000 mg/L, no further testing was required.

- A stock solution of the reference substance was prepared in reagent water at a concentration of 0.500 mg/mL and was used to add reference substance to the appropriate flasks. Stock solution volumes of 3.2, 10, and 32 mL were added to the 3.2, 10, and 32 mg/L test flasks, respectively.

Vehicle:

no

Details on test solutions:

no data

Test organisms (species):

activated sludge, domestic

Details on inoculum:

-Source of inoculum: Activated sludge, Columbia Wastewater Treatment Plant, Columbia, Missouri
- Preparation of inoculum for exposure: Repeated (11 times) centrifugation of 250 mL aliquots to concentrate the inoculum, followed by 3 rinses in ABC well water, and final suspension in a carboy with stirring and aeration with compressed air. The inoculum was sustained with a synthetic feed solution overnight. Suspended solids concentration was determined in triplicate, and the solution diluted with well water to a final suspended solids concentration between 3.6 and 4.4 g/L.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

30 min

Post exposure observation period:

None

Hardness:

N/A

Test temperature:

19.8-20.2 °C

pH:

8.03- microbial inoculum
8.23-8.35-test flasks, reference, and controls
8.23- abiotic control contact flask (containing no microbial inoculum)

Dissolved oxygen:

Tested parameter- see Results

Salinity:

N/A

Nominal and measured concentrations:

Nominal concentrations:
Test substance- 0 (control), 10, 32, 100, 320, and 1000 mg test substance/L
Reference substance- 3.2, 10 and 32 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type: closed
- Material, size, headspace, fill volume: Glass 1 L, 200 mL inoculum added to flask for 30 min exposure, 500 mL final volume
- Aeration: 500-1000 mL/min
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2 control, 1 abiotic control, 3 concentrations (1 each) reference substance

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: ABC Labs well water

OTHER TEST CONDITIONS
- Adjustment of pH: None
- Light intensity: Ambient

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Oxygen consumption mg/L/hr, one reading per concentration.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2

Reference substance (positive control):

yes

Remarks:

3,5 Dichlorophenol

Duration:

30 min

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:

30 min

Dose descriptor:

EC50

Effect conc.:

14.4 mg/L

Nominal / measured:

nominal

Conc. based on:

other: 3, 5 dichlorophenol-reference substance

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: acceptable value

Details on results:

Test Substance:
The test substance showed 12.4, 31.1, 11.3, 14.8, and 17.9% inhibition at concentrations of 10, 32, 100, 320, and 1,000 mg/L, respectively. Thus, the estimated 30-minute-EC50 value for sodium tungstate was estimated to be >1,000 mg (total product)/L. No further testing was required.

Controls:
- Respiration rates for the control flasks were 81.0 and 71.7 mg O2L-1hr-1 during the 30-minute exposure. These respiration rates were within 15% of each other. The respiration rate of the abiotic control was 0.0 mg O2L-1hr-1, indicating that rate of oxygen uptake by sodium tungstate dihydrate was effectively 0% of the mean respiration rate of the controls, 76.4 mg O2L-1hr-1.

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels: The percent inhibitions for the three reference toxicant substance flasks were 22.6, 34.3, and 83.8% at 3,5 dichlorophenol nominal concentrations of 3.2, 10, and 32 mg/L, respectively
- Other: The 30 min EC50 for the reference substance of 14.4 mg/L well within the 5-30 mg/L acceptance range required by the method.

Reported statistics and error estimates:

no data

- The ASR system provided the oxygen consumption/depletion curve as a plot of the dissolved oxygen concentration (mg O2/L) versus time (seconds). The analyst selected the appropriate start and end times between which the oxygen depletion curve was linear, and the ASR system automatically calculated the oxygen consumption rate (respiration rate) and expressed these rates as mg O2L-1hr-1.

Conclusions:

The 30 minute EC50 value for sodium tungstate dihydrate to activated sludge is > 1000 mg/ L.

Executive summary:

No microorganism toxicity data of sufficient quality were available specifically on Ammonium metatungstate (target substance). However, microorganisms toxicity data are available on sodium tungstate (source substance), which are used for read-across. Due to similar water solubility and toxicity for the target substance compared to the source substance, the resulting read-across from the source substance to the target substance is appropriate for this endpoint. In addition, read-across is appropriate because the classification and labelling is similar for the source substance and target substance, the PBT/vPvB profile is the same, and the dose descriptors are, or are expected to be, conservative for the target substance. For more details, refer to the read-across category approach description in the Category section of this IUCLID submission or Annex 3 of the CSR.

Description of key information

No data on effects on microorganisms are available for ammonium metatungstate; therefore, read-across from ammonium paratungstate is used

for this endpoint. In an activated sludge respiration inhibition test (ASRIT) testing activated sludge of predominantly domestic sewage, a 3-h EC50 of >10,000 mg APT/L (ca. 7040 mg W/L) based on respiration rate and nominal concentrations was reported.

Key value for chemical safety assessment

EC50 for microorganisms:

7 000 mg/L

Additional information

No data of sufficient quality on the toxicity to soil microorganisms are available for ammonium metatungstate (target substance). However, data are available for ammonium paratungstate (source substance), which were used for read-across.

 

Due to similar or lower transformation/dissolution results for ammonium metatungstate (target substance) than ammonium paratungsate (source substance), the resulting toxicity potential is expected to be similar or lower, so read-across is appropriate. In addition, read-across is justified because the classification and labelling is the same or less severe for the target substance and the PBT/vPvB profile is the same. Finally, the dose descriptors are, or are expected to be, sufficiently similar or higher for the target substance, and read-across to the source substance is adequately protective. For more details, refer to the read-across category approach description in the Category section of this IUCLID submission or Annex 3 of the CSR.