Oxazolidine, diheptyl~

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:

2016-12-08 - 2017-02-22

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Duplicate samples from the freshly prepared test media (containing algae) of all test concentrations and from the control were taken at the start of the test.
For the determination of the stability of the test item under the test conditions and of the maintenance of the test item concentrations during the test period, duplicate samples from the test media of all test concentrations and the control (containing algae) were taken during the test after 24 and 48 hours from the additional replicates for analyses of each treatment group, and at test end (after the 72 hours test period).

Test solutions

Vehicle:

no

Details on test solutions:

Test Concentrations:
110, 35, 11, 3.5 and 1.1 mg test item/L, and a control
corresponding to following geometric mean measured concentrations of the test item:
2.32, 0.881, 0.591, 0.368 and 0.082 µg test item/L, and a control.

A defined amount of the test item was added directly to the test water of the highest test concentration and was carefully stirred for 24 hours in the dark to dissolve as much of the test item as possible. The highest test item loading of 110 mg test item/L was prepared by mixing 110.1 mg test item into 1000.9 mL test water. After cessation of mixing and a following period (1 hour) of settling to allow phase separation, the aqueous phase, i.e. the water accommodated fraction, was drawn off carefully and used as the test medium of the highest test concentration. The pH was adjusted to 8.3 and the adequate volumes of this water accommodated fraction were mixed into test water to obtain the desired concentrations of nominal 110, 35, 11, 3.5 and 1.1 mg test item/L.
The test media were prepared just before introduction of the algae (= start of the test).

Test organisms

Test organisms (species):

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

Details on test organisms:

The algae were supplied by the „Sammlung von Algenkulturen, Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Universität Göttingen", 37073 Göttingen, Germany.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Hardness:

0.24 mmol/L (= 24 mg/L) as CaCO3

Test temperature:

22 to 24 °C

pH:

8.0 to 8.3 at test start
8.7 to 8.8 at test end

Nominal and measured concentrations:

Nominal concentration Geometric mean measured concentration
[mg/L] [µg/L]
Control n.a.
1.1 0,0187
3.5 0.368
11 0.591
35 0.881
110 2.32

Reference substance (positive control):

yes

Remarks:

For the evaluation of the quality of the algae and the experimental conditions the reference item potassium dichromate is tested at least twice a year to demonstrate satisfactory test conditions.

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 110 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

> 110 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 110 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Effect concentrations 4

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

>= 110 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Effect concentrations 5

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 2.32 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Effect concentrations 6

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

> 2.32 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Effect concentrations 7

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 2.32 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Effect concentrations 8

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 2.32 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Effect concentrations 9

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 110 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 10

Key result

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

> 110 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 11

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 110 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 12

Key result

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

>= 110 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 13

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 2.32 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 14

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

> 2.32 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 15

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 2.32 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 16

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 2.32 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The influence of test item on the growth of the freshwater green algae Pseudokirchneriella subcapitata was assessed in a static concentration-response test. The 72-hour NOEC was determined to be at least the water accommodated fraction (WAF) of nominal 110 mg test item/L, corresponding to a geometric mean measured concentration of 2.32 µg test item/L. The actual NOEC may be above this concentration, but concentrations in excess of nominal 110 mg test item/L, corresponding to a geometric mean measured concentration of 2.32 µg test item/L or the limit of solubility have not been tested according to the recommendations of the test guidelines. The 72-hour LOEC and the 72-hour EC50 were clearly higher than WAF of nominal 110 mg test item/L, corresponding to a geometric mean measured concentration of 2.32 µg test item/L. These values could not be quantified due to the absence of toxicity of the test item up to the WAF of nominal 110 mg test item/L, corresponding to a geometric mean measured concentration of 2.32 µg test item/L, representing the limit of solubility in this study.
The concentrations of the test item were determined in the duplicate test media samples from all test concentrations (the saturated WAF stock solution and its dilutions) and the duplicate control samples from all sampling times. All reported results refer to geometric mean measured concentrations, since the measured initial test item concentrations degraded by more than 20% over the course of the test.
The test substance is not toxic at loadings significantly above the limit of solubility.

Executive summary:

The influence of the test item on the growth of the freshwater green algae Pseudokirchneriella subcapitata was assessed in a static concentration-response test. The 72-hour NOEC was determined to be at least the water accommodated fraction (WAF) of nominal 110 mg test item/L, corresponding to a geometric mean measured concentration of 2.32 µg test item/L. The actual NOEC may be above this concentration, but concentrations in excess of nominal 110 mg test item/L, corresponding to a geometric mean measured concentration of 2.32 µg test item/L or the limit of solubility have not been tested according to the recommendations of the test guidelines. The 72-hour LOEC and the 72-hour EC50 were clearly higher than WAF of nominal 110 mg test item/L, corresponding to a geometric mean measured concentration of 2.32 µg test item/L. These values could not be quantified due to the absence of toxicity of the test item up to the WAF of nominal 110 mg test item/L, corresponding to a geometric mean measured concentration of 2.32 µg test item/L, representing the limit of solubility in this study.

The concentrations of the test item were determined in the duplicate test media samples from all test concentrations (the saturated WAF stock solution and its dilutions) and the duplicate control samples from all sampling times. All reported results refer to geometric mean measured concentrations, since the measured initial test item concentrations degraded by more than 20% over the course of the test.

The teast substance is not toxic at loadings significantly above the limit of solubility.