(E)-1,2-difluoroethylene

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:

Experimental starting date: June 23 2020 Experimental completion date: June 26 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: "Algal Growth Inhibition Test" stipulated in the "Testing Methods for New Chemical Substances" of Japanese Chemical Substances Control Law

Version / remarks:

Latest revision: July 1st 2019

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Chemical name; (E)-1,2,-Difluoroethylene
Other name: TKN1

Purity of test item: 99.9989% (GC area)

Colourless gas
Flammable, stable in dark storage space at room temperature

Analytical monitoring:

yes

Details on sampling:

Concentration of test item in the test solution
Frequency of measurement: At the stanrt and end of exposure

Sample for measurement:
Another solution sampled from the preparation container (at the start of exposure)
The test solution taken out from the test vessels in each test level for analytical chemistry, at 24 and 48 hours after the start of exposure
the mixed solution taken out with equal volume if the test solution from the test vessels on each test level (at the end of exposure)

Volume of sample
Approximately 10 mL (all test levels, at the start of exposure)
100 mL (all test levels, at 24 and 48 hours after the start of exposure)
Approximately 12 mL (all test levels, at the end of expopsre)

Vehicle:

no

Details on test solutions:

After approximately 700 mL of the medium was added in 1L sampling bag for gas analysis (Tedlar bag), about 150 mL gaseous test sample (approximately 3 minutes at about 50 mL/min) was enclosed in the bag. It was then shaken overnight at room temperature to prepare the stock solution. The day that the test solution of 250 mg/L was prepared, the test item concentration of the stock solution was measured. The measured concentration of the test item in the stock solutin was 943 mg/L. required volumes of the stock solution and the medium were mixed and stirred in a preparation container to prepare the test solution which was divided into each test vessel.

Test organisms (species):

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

Details on test organisms:

Source: American Type culture Collection
Strain number: ATCC 22662
Supplied date: June 20, 1995
Sub-culture: Passage cultured under sterile conditions at the test facility

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

21-24°C (not varied by more than +/- 2°C)

pH:

Another solution sampled separately from the preparation container was measured (at the start of exposure)
One test vessel in each test level was measured (at the end of exposure)

7.8 at start of exposure
9.5 at end of exposure

Salinity:

Not applicable as freshwater study

Nominal and measured concentrations:

250 mg/L as nominal concentration
29.9 mg/L as measured concentration

Details on test conditions:

Type of test: Incubation with rotary shaking (approximately 100 rpm), closed system
Test vessel: 500 mL Erlenmeyer flask (closed vessel)

Replicate: 6 replicates/test level
(One additional replicate for measuring the value of background and that for analytical chemistry of the tets item was set for 24 and 48 hours, respectively)

Volume of test solution: 600 mL/test level (100 mL/test vessel)

Light condition: 88-90 µmol m-2 s-1

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 29.9 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 29.9 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

ErC50 and NOEC:
As the results of cell observation, the condition of cells in the 29.9 mg/L exposure level group was the same as the control.
As a result of the statistical analysis of the growth rate, a statistically significant difference was not found.

Appearance of test solution:
At the start of exposure, test solutions of 29.9 mg/L exposure level and control were colorless and clear. At the end of exposure, they were green due to algal growth.

Water quality and environment conditions:
The measured values of pH were 7.9 - 9.5. The pH of control varied more than the range described in the guideline (not varied more than 1.5 in usual case). Culture temperature in the incubator were 22.0 - 22.1°C.

Concentration of test item in test solution:
The measured concentrations of the test item in the test solutions were 139 mg/L at the start of exposure, 17.3 mg/L at 24 hours after the start of exposure, 15.5 mg/L at 48 hours after the start of exposure and 14.7 mg/L at the end of exposure. Those were 12.5%, 11.2% and 10.6% at the start of exposure, respectively. The time-weighted mean measured concentration was 29.9 mg/L.

Validity of test
a) Growth of control: the cells in the control cultures grew exponentially during the exposure. At the end of exposure, it increased to a factor of 62 or more of the number of initial cells in the control cultures. this meets the validity of test; the cell growth in the control cultures should increase by a factor of at least 16 at 72 hours after the start of exposure.

b) Specific growth rates of section-by-section control
The mean coefficient of variation for section-by-section specific growth rates in the control cultures was 28%. It meets the validity criteria of the test: the mean coefficient of variation in the control cultures must not exceed 35%.

c) Specific growth rates in replicate controls
The coefficient of variation of average specific growth rates in replicate control cultures was 1.8%. It meets the validity criteria of the test: the coefficient of variation in control cultures must not exceed 75.

Results with reference substance (positive control):

An algal growth inhibition test with potassium dichromate was periodically conducted. The latest data gave a result of ErC50 (0-3d) 1.3 mg/L. This value was within the stipulated range for the test facility.

Value of biomass at each time

Measured concentration (mg/L)	Vessel	Cell concentration (x10^4cells/mL)
		0 hour*	24 hours	48 hours	72 hours
Control	A	0.5	2.9	13	33
	B	0.5	3.0	13	35
	C	0.5	3.0	13	39
	D	0.5	2.8	13	31**
	E	0.5	2.7	14	33
	F	0.5	2.7	13	32
	Mean	0.5	2.9	13	34
	S.D	0	0.13	0.4	2.7
29.9	A	0.5	2.6	11	30
	B	0.5	2.6	12	31
	C	0.5	2.9	12	35
	D	0.5	2.8	13	36
	E	0.5	2.9	14	33
	F	0.5	2.8	12	33
	Mean	0.5	2.8	13	33
	S.D	0	0.13	1.2	2.3

*value based on the measured value of pre-culture

**The minimum cell growth in the control (biomass at the end of exposure / biomass at the start of exposure) 31/0.5 = 62

 

Growth rate and growth inhibition rate

Measured concentration (mg/L)	Vessel	Growth rate (0-3d)	Growth Inhibition rate (%)
Control	A	1.40	-
	B	1.42	-
	C	1.45	-
	D	1.38	-
	E	1.40	-
	F	1.39	-
	Mean	1.41	-
	S.D.	0.0255	-
29.9	A	1.36	3.3
	B	1.38	1.8
	C	1.42	-0.88
	D	1.42	-1.2
	E	1.40	0.44
	F	1.39	0.79
	Mean	1.40	0.70
	S.D.	0.0234	1.7

 

 

 

Validity criteria fulfilled:

yes

Conclusions:

ErC50 of the test item based on the growth rate as > 29.9 mg/L.

The NOEC based on the growth rate was >/= 29.9 mg/L.

Executive summary:

The objective of the study was to determine the EC50 and NOEC of the test substance following a 72 -hr exposure to Pseudokirchineriella subcapitata. The guideline followed was OECD Guidelines for Testing of Chemicals, No. 201, "Freshwater alga and Cyanobacteria, Gorwth Inhibition Test".

 

Six replicates were exposed to a nominal concentration of 250 mg/L (29.9 mg/L as measured concentration) for a period of 72 hours.

 

ErC50 of the test item based on the growth rate as >29.9 mg/L. The NOEC based on the growth rate was >/= 29.9 mg/L.

Description of key information

 

The objective of the study was to determine the EC50 and NOEC of the test substance following a 72 -hr exposure to Pseudokirchineriella subcapitata. The guideline followed was OECD Guidelines for Testing of Chemicals, No. 201, "Freshwater alga and Cyanobacteria, Growth Inhibition Test".

 

Six replicates were exposed to a nominal concentration of 250 mg/L (29.9 mg/L as measured concentration) for a period of 72 hours.

 

ErC50 of the test item based on the growth rate as >29.9 mg/L. The NOEC based on the growth rate was >/= 29.9 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

29.9 mg/L

EC10 or NOEC for freshwater algae:

29.9 mg/L