Reaction mass of 3,7-dimethyloct-7-en-1-yl 3-methylbut-2-enoate and 3,7-dimethyloctyl 3-methyl-2-butenoate and citronellyl 3-methylcrotonate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From June,19 2017 to September 22,2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch Number: VE00463145
Appearance: Colorless to pale yellow liquid
Purity: 99.9 % (sum of the isomers)
Expiration Date: April 06, 2018

Analytical monitoring:

yes

Details on sampling:

As the test item is a volatile substance, the test was performed using glass stoppered Erlenmeyer flasks (closed system) completely filled with test medium, minimizing the air space in the flasks and avoiding potential losses of test item by evaporation.

Vehicle:

yes

Details on test solutions:

Since the test item is a liquid with low water solubility, the slow-stirring method was applied for preparation of a saturated test item solution.
For this, the test item with a density of 0.8957 g/cm3 (at 20°C) was carrefully applied on to the surface of the test water at a loading rate of 100 mg/L.
The equilibrated aqueous phase with a loading rate of 100 mg/L, containing dissolved test item only, was used as the highest test concentration and was diluted with test water to obtain the dilutions 1:2, 1:4, 1:8 and 1:16.
Additionally a control (test water without test item) was tested in parallel.

Test organisms (species):

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

Details on test organisms:

The test organism used for the study was Pseudokirchneriella subcapitata, Strain No. 61.81 SAG

Test type:

static

Water media type:

other: AAP Medium

Total exposure duration:

72 h

Hardness:

0.15 mmol/L (= 15 mg/L as CaCO3)

Test temperature:

24°C

pH:

7.5

Nominal and measured concentrations:

At the start of the main test, the highest concentrated test medium (i.e. the undiluted equilibrated test medium with a loading rate of 100 mg/L) was prepared following the slow-stirring method
(see Section 5.5 of the report) with a stirring period of 48 hours at room temperature in the dark. For this, 259 μL of test item were carefully applied (pipetted) onto the surface of 2320 mL test water.
This volume is equivalent to a loading rate of 100 mg/L, considering the density of the test item of 0.8957 g/cm3 (at 20 °C). No auxiliary solvent or emulsifier was used.
The equilibrated aqueous phase with a loading rate of 100 mg/L, containing dissolved test item only, was used as the highest test concentration and was diluted with test water to obtain the
test media with the lower test concentrations, i.e. the dilutions 1:2, 1:4, 1:8 and 1:16.
Additionally, a control (test water only) was run in parallel. The test media were prepared just before the start of the test.

Nominal and TWA Measured Concentrations :

Concn. Level /
Dilution of Satd. Solution TWA Measured Concn. (mg/L)

1 : 16 0.0026 mg/L
1 : 8 0.0038 mg/L
1 : 4 0.023 mg/L
1 : 2 0.044 mg/L
Undiluted 0.11 mg/L

Details on test conditions:

Based on the results of the range-finding test and in agreement with the Sponsor the following concentrations of SINODOR CQ were selected for the main test: the equilibrated test medium
with a loading rate of 100 mg/L and the dilutions 1:2, 1:4, 1:8 and 1:16. Additionally, a control (test water without test item) was tested in parallel.

Reference substance (positive control):

yes

Remarks:

Potassium Dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.11 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.028 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.023 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.072 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

cell number

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.04 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

cell number

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.023 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

cell number

Results with reference substance (positive control):

For evaluation of the algal quality and experimental conditions, potassium dichromate is tested as a positive control twice a year to demonstrate satisfactory test conditions. In the latest reference test (IES Study Number 20170077 from May 2017), the 72-hour EC50 for growth rate was 1.0 mg/L and showed that the sensitivity of the test system was within the range recommended by the guideline (72-hour EC50 for the growth rate 0.9-1.5 mg/L).

Reported statistics and error estimates:

The values for the validity criteria of the test were calculated by the statistical software program ToxRat Professional®.

Validity criteria fulfilled:

yes

Conclusions:

A clear concentration-response relationship was observed for both biological endpoints growth rate and yield over the exposure period of 72 hours.
A statistically significant inhibitory effect on the growth rate and on the yield of the algae was observed at the end of the test at the concentrtaion of 0.044 mg/L, and above.

72 hr ErC50 > 0.11 mg/L
72 hr ErC10 = 0.028 mg/L
72 hr NOErC = 0.023 mg/L
72 hr EyC50 = 0.072 mg/L
72 hr EyC10 = 0.040 mg/L
72 hr NOEyC = 0.023 mg/L

Executive summary:

The impact of the test item SINODOR CQ on the growth of the freshwater green algal species

Pseudokirchneriella subcapitata was investigated in a 72-hour static test according to the

OECD Guideline 201 (2006, corrected 2011) and the Commission Regulation (EU)

No 2016/266, C.3.

As the test item is a volatile substance, the test was performed using glass stoppered Erlenmeyer

flasks (closed system) completely filled with test medium, minimizing the air space in the flasks

and avoiding potential losses of test item by evaporation.

Since the test item is a liquid with low water solubility, the slow-stirring method (to avoid

formation of an emulsion) was applied for preparation of a saturated test item solution. For this,

the test item with a density of 0.8957 g/cm3 (at 20 °C) was carefully applied (pipetted) on to

the surface of the test water at a loading rate of 100 mg/L. Thereafter slow-stirring was applied

for 48 hours in a closed vessel to reach a maximum concentration of dissolved test item in the

test water. The stirring vessel was nearly completely filled (a small headspace had to be

included as the test item was floating on the water surface) and tightly sealed with glass stoppers

to avoid losses of the volatile test item during stirring.

After this treatment the lower part of the equilibrated test medium was carefully harvested from

the stirring vessel through a tap at the bottom of the vessel. This equilibrated aqueous phase

with a loading rate of 100 mg/L, containing dissolved test item only, was used as the highest

test concentration and was diluted with test water to obtain the dilutions 1:2, 1:4, 1:8 and 1:16.

Additionally, a control (test water without test item) was tested in parallel.

The preparation of the test media was based on the OECD Guidance Document No. 23 on

Aquatic Toxicity Testing of Difficult Substances and Mixtures, 2000.

The measured concentrations of the test item SINODOR CQ in the test media of all test

concentrations at the start, after 24 hours and at the end of the test are shown in the table below.

Due to the decrease of test item concentrations during the test period, the mean measured test

item concentrations were calculated as the time-weighted means over all measurements.

The biological results are based on the mean measured time-weighted test item concentrations.

A clear concentration-response relationship was observed for both biological endpoints growth

rate and yield over the exposure period of 72 hours. A statistically significant inhibitory effect

on the growth rate and on the yield of the algae was observed at the end of the test at the

concentration of 0.044 mg/L, and above.

 

 Endpoint after 72 HoursGrowth Rate [mg/L]

Yield [mg/L]

EC10

(95 % Confidence Interval)

 0.028 

(0.026-0.030)

0.040 

(0.037-0.043)

 

EC50

(95 % Confidence Interval)

  

>0.11 

n.d.

  

0.072 

(0.069-0.075)

 NOEC

0.023

0.023

Description of key information

A clear concentration-response relationship was observed for both biological endpoints growth rate and yield over the exposure period of 72 hours. A statistically significant inhibitory effect on the growth rate and on the yield of the algae was observed at the end of the test at the concentration of 0.044 mg/L, and above.

72 hr ErC50 > 0.11 mg/L

72 hr ErC10 = 0.028 mg/L

72 hr NOErC = 0.023 mg/L

72 hr EyC50 = 0.072 mg/L

72 hr EyC10 = 0.040 mg/L

72 hr NOEyC = 0.023 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:

0.11 mg/L

EC10 or NOEC for freshwater algae:

0.028 mg/L

Additional information

72 hr ErC50 > 0.11 mg/L

72 hr ErC10 = 0.028 mg/L

72 hr NOErC = 0.023 mg/L

72 hr EyC50 = 0.072 mg/L

72 hr EyC10 = 0.040 mg/L

72 hr NOEyC = 0.023 mg/L