TETRASODIUM ETHYLENE 1,1-DIPHOSPHONATE

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2002-05-14 - 2002-05-16

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Report date:

2002

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.6800 (Modified Activated Sludge, Respiration Inhibition Test for Sparingly Soluble Chemicals)

GLP compliance:

yes (incl. QA statement)

Remarks:

2000-04-26

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

443-520-7

EC Name:

-

Cas Number:

33016-77-2

Molecular formula:

C2H4Na4O6P2

IUPAC Name:

tetrasodium (1-phosphonatoethenyl)phosphonate

Test material form:

solid

Specific details on test material used for the study:

- Synonyms: ITC 908, vinylidenephosphonic acid tetrasodium salt (VDPA tetrasodium salt)
- Lot/batch No.of test material: 562CH/646
- Purity: 87.33%
- Storage condition of test material: Room temperature, in the dark

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: A mixed population of activated sewage sludge micro-organisms was obtained on 16 May 2002 from the aeration stage of the Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK which treats predominantly domestic sewage.
- Preparation of inoculum for exposure: The sample was maintained on continuous aeration in the laboratory at a temperature of 21 °C and was used on the day of collection.
- Concentration of sludge: Determination of the suspended solids level of the activated sewage sludge was carried out by filtering a sample (100 ml) of the activated sewage sludge by suction through a piece of pre-weighed GF/A filter paper using a Buchner funnel. The piece of GF/A filter paper was then dried in an oven at approximately 110 °c for 1 hour and allowed to cool before reweighing. The suspended solids was equal to 4.0 g/L prior to use.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test conditions

Test temperature:

21 °C

pH:

7.9 - 8.1

Nominal and measured concentrations:

Range-finding test 1: 1.0, 10, 100 and 1000 mg/L
Range-finding test 2: 2000 mg/L
Definitive test: 32, 100, 320, 1000 and 3200 mg/L

Details on test conditions:

TEST SYSTEM
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The test water used for both the range-finding and definitive tests was laboratory tap water dechlorinated by passage through an activated carbon filter and partly softened giving water with a total hardness of approximately 100 mg/L as CaCO3. After dechlorination and softening the water was then passed through a series of computer controlled plate heat exchangers to achieve the required temperature.

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: Normal laboratory lighting conditions

TEST CONCENTRATIONS
Range finding study
- Test concentrations: 1) 1.0, 10, 100 and 1000 mg/L; 2) 2000 mg/L
- Results used to determine the conditions for the definitive study: Inhibition of respiration (14%) was observed at 1000 mg/L in the initial range-finding test, howevere, there were no significant effects on respiration at 1.0, 10 and 100 mg/L. Therefore, in order to confirm that the result obtained from the initial range-finding test at the test contration of 1000 mg/L was signification a second range-finding test was conducted at a test concentration of 2000 mg/L. Significant inhibition of respiration was observed at 2000 mg/L in the second range finding test.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol: 3.2, 10 and 32 mg/L

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

2 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Effect concentrations 2

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

1 500 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Effect concentrations 3

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

320 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

In some instances, the initial and final dissolved oxygen concentrations were below those recommended in the test guidelines. This was considered to have had no adverse effect on the results of the study given that in all cases the oxygen consumption rate was determined over the linear portion of the oxygen consumption trace.

Results with reference substance (positive control):

30min EC50: 17 mg/L
3h EC50: 12 mg/L

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The effect of the test material on the respiration of activated sewage sludge micro-organisms gave a 3-hour EC50 of 1500 mg/L. The NOEC after 3 hours exposure was 320 mg/L

Executive summary:

The effect of the test material on the respiration of activated sewage sludge micro-organisms was tested according to OECD TG 209 and under GLP conditions. A 3-hour EC50 of 1500 mg/L was determined. The NOEC after 3 hours exposure was 320 mg/L