Phosphoric acid, ethyl ester

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2015-02-26 - 2015-06-11

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Ethyl dihydrogen phosphate

EC Number:

216-603-9

EC Name:

Ethyl dihydrogen phosphate

Cas Number:

1623-14-9

Molecular formula:

C2H7O4P

IUPAC Name:

Phosphoric acid,monoethyl ester

Test material form:

liquid

Specific details on test material used for the study:

Test item: Hordaphos MDE
CAS number: 37203-76-2
Purity: 98.8 %

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

The test item concentrations were weighed out directly in Erlenmeyer flasks.

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Test System: Activated sludge
Origin: Municipal sewage treatment plant of 31137 Hildesheim, Germany
Reason for the selection: Non-adapted activated sludge from the sewage plant at Hildesheim is well suited as it receives predominantly municipal sewage and hardly any industrial chemical waste.
Pretreatment: The sludge was washed twice with chlorine free tap water and adjusted to a dry sludge concentration of 3.0 g/L ± 10 %. The sludge was used within 24 h after sampling.

Dry sludge concentration: 2.91 g/L, corresponding to 1.46 g/L in the test vessel

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test conditions

Test temperature:

Nominal: 18-22 °C, actual: 21.0 °C

Nominal and measured concentrations:

Nominal test item concentration [mg/L]:10, 32,100,320, 1000, 1000

Reference substance (positive control):

yes

Remarks:

Copper (II) sulphate pentahydrate p.a.

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Effect concentrations 2

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

375 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Results with reference substance (positive control):

In the reference test the ECso-value for copper (II) sulphate pentahydrate was determined by probit analysis with:
EC5o = 111 mg/L 95%
Confidence Interval = 107-115 mg/L
This is in the recommended range of validity of 53 - 155 mg/L.

Any other information on results incl. tables

Biotic and Abiotic Factors

pH-value of the activated sludge	7.75
pH-value of the synthetic waste water	7.38
Dry solids concentration [g/L] of sludge	2.91
Dry solid concentration [g/L] in test solution	1.46
Test temperature [°C]	21.0

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The NOEC of Hordaphos MDE is 100 mg/L. The test item is not toxic up to the concentration of 100 mg/L to activated sludge of a municipal sewage treatment plant. The EC10 is 226 mg/L, the EC50 is 375 mg/L and EC8o is 439 mg/L of the test item.

Executive summary:

A Respiration Inhibition Test with activated sludge according to OECD Guideline No. 209 was carried out with the test item Hordaphos MDE (batch number: DEH2 031109) from 2015-03-30 to 2015-03-31 . The test system was activated sludge of the municipal treatment plant of 31137 Hildesheim, Germany. The test was carried out under static conditions with the test item concentrations 10 - 32 - 100 - 320 - 1000 - 1000 pH mg/L. The respiration rates of the control, reference and test item replicates were measured after a contact time of three hours, and the inhibitory effects of the test and reference item were determined in comparison to the control respiration rates. The mean inhibition of respiration for the test item replicates ranged from 8 % to 97 % . Additionally, replicates with 1000 mg/L and pH-adjustment were prepared. The mean inhibition of the respiration of these replicates was -17 %.

In order to check the activity of the test system and the test conditions a reference test was carried out with copper (II) sulphate pentahydrate as reference item and the reference toxicity was determined. The EC5o-value for the reference item was 111 mg/L.

The NOEC of Hordaphos MDE is 100 mg/L. The test item is not toxic up to the concentration of 100 mg/L to activated sludge of a municipal sewage treatment plant. The EC10 is 226 mg/L, the EC50 is 375 mg/L and EC8o is 439 mg/L of the test item.