Propan-2-yl N-[(S)-(pentafluorophenoxy)(phenoxy) phosphoryl]-L-alaninate

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12 November 2012-20 December 2012

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Propan-2-yl N-[(S)-(pentafluorophenoxy)(phenoxy)-phosphoryl]-L-alanine

EC Number:

695-076-0

Cas Number:

1334513-02-8

Molecular formula:

C18H17F5NO5P

IUPAC Name:

Propan-2-yl N-[(S)-(pentafluorophenoxy)(phenoxy)-phosphoryl]-L-alanine

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

Test item
- Identification: GS-606962
- Description: White powder
- Substance type: organic
- Lot/batch No.: PSI-172(2)-1-1-12001
- Storage condition of test material: room temperature in the dark

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)

Study design

Water media type:

freshwater

Total exposure duration:

72 h

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.079 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

other: 100% v/v saturated solution

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.079 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

other: 100% v/v saturated solution

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

50 other: % v/v saturated solution

Nominal / measured:

meas. (geom. mean)

Conc. based on:

other: 50% v/v saturated solution

Basis for effect:

growth rate

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The effect of the test item on the growth of Pseudokirchneriella subcapitata has been investigated and gave EC50 values on the geometric mean measured test concentrations of greater than 0.079 mg/L. The No Observed Effect Concentration (NOEC) was determined to be 50% v/v saturated solution. Correspondingly the Lowest Observed Effect Concentration (LOEC) was determined to be 100% v/v saturated solution (equivalent to a geometric mean measured test concentration of 0.079 mg/L).

Executive summary:

Introduction

A study was performed to assess the effect of the test item on the growth of the green alga Pseudokirchneriella subcapitata.

The method followed that described in the OECD Guidelines for Testing Chemicals (2006) No 201, "Freshwater Alga and Cyanobacteria, Growth Inhibition Test" referenced as Method C.3 of Commission Regulation (EC) No 761/2009.

Methods

Pre-study solubility work conducted indicated that it was not possible to obtain a testable solution of the the test item using traditional methods of preparation e.g. ultrasonication and high shear mixing.

A pre-study media preparation trial indicated that a dissolved test item concentration of approximately 0.17 mg/L was obtained from a saturated solution method of preparation indicating this to be the limit of water solubility of this item under test conditions.

Following a preliminary range-finding test, Pseudokirchneriella subcapitata was exposed to solutions of the test item at measured concentrations of 6.25, 12.5, 25, 50 and 100% v/v saturated solution (3 replicates flasks per concentrations) for 72 hours, under constant illumination and shaking at a temperature of 24 ± 1°C. The test item solutions were prepared by stirring an excess (50 mg/L) of test item in culture medium using a propeller stirrer at approximately 1500 rpm for 24 hours. After the stirring period any undissolved test item was removed by filtration (0.2 µm Sartorius Sartopore filter, first approximate 2 liters discarded in order to pre-condition the filter) to produce a 100% v/v saturated solution of the test item. The saturated solution was then further diluted as necessary, to provide the remaining test groups.

Samples of the algal population was removed daily and cell concentrations determined for each control and treatment group, using a Coulter Multisizer Partlicle Counter.

Results

Chemical analysis of the 6.25, 12.5, 25 and 50% v/v saturated solution test preparation ast 0 hours showed measured test concentrations of less than the limit of quantitation (LOQ) of the analytical method employed were obtained which was determined to be 0.071 mg/L. A measured concentration of 0.17 mg/L was obtained for the 100% v/v saturated solution test preparation. Analysis of the test preparations at 72 hours showed measured test concentrations of less than the LOQ were obtained for all test preparations indicating that the test item was unstable over the test period.

Given the decline in measured test concentration it was considered appropriate to calculate the results on the geometric mean measured test concentrations.

Exposure of Pseudokirchneriella subcapitata to the test item gave EC₅₀ values based on the geometric mean measured test concentrations of greater than 0.079 mg/L.

The No Observed Effect Concentration (NOEC) was determined to be 50% v/v saturated solution, correspondingly the Lowest Observed Effect Concentration (LOEC) was determined to be 100% v/v saturated solution (equivalent to 0.079 mg/L based on the geometric mean measured test concentrations).