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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From January 12, 2018 to March 27, 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
GLP compliance:
yes
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
- Source: Culture Collection of Algae at Goettingen University
Test type:
static
Water media type:
freshwater
Total exposure duration:
72 h
Test temperature:
22.3 to 22.4 °C
pH:
8.1-8.8
Nominal and measured concentrations:
Nominal concentrations for the definitive test: 1, 3.2, 10, 32 and 100 mg/L
Details on test conditions:
- Test vessel: 250ml glass Erlenmeyer
- Test volume: 100 mL
- No. of vessels per concentration (replicates): 3 replicates per each concentration
- No. of vessels per control (replicates): 3 replicates
- Light: 4716 lux (average)
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Key result
Duration:
72 h
Dose descriptor:
EC50
Remarks:
ErC50
Effect conc.:
61.75 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Remarks:
EyC50
Effect conc.:
25.86 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks:
yield
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: algal growth
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
32 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: growth
Results with reference substance (positive control):
72-hours EyC50 of the reference substance was 0.79 mg/L.

Table 1. Nominal and Effective Concentrations of Test Solutions and Their Respective Deviations.

Nominal concentration

(mg/L)

Mean of effective concentration of test substance (Ctsmean)

(mg/L)

|Deviation| (|Dev|)

(%)

Control

< LQ

nd

1

1.1539

15.39

3.2

3.0007

6.23

10

10.1608

1.61

32

31.9459

0.17

100

97.5803

2.42

nd: not determined.

<LQ: lower than the practical limit of quantification (1.01μg/mL)

 

Table 2. Daily cell counts in control replicates.

Control replicate

Cells density (cells/mL)

Exponential increase of the biomass of the control group – 72 hours

 

Day 0

Day 1

Day 2

Day 3

135

1

5000

40000

200000

650000

2

5000

40000

200000

690000

3

5000

30000

220000

680000

Average

5000

36667

206667

673333

 

Table 3. Calculation of Percentage Coefficient of Variation for section-by-section specific growth rates.

Control replicate

Section-by-section specific growth rates (day-1)

Average

(day-1)

Standard deviation (sd)

(day-1)

Coefficient of variation (%)

%CV

Day 0-1

Day 1-2

Day 2-3

1

2.0794

1.6094

1.1787

1.6225

0.4505

27.8

2

2.0794

1.6094

1.2384

1.6424

0.4215

25.7

3

1.7918

1.9924

1.1285

1.6376

0.4522

27.6

Average section-by-section %CV

27.0

Table 4. Calculation of Percentage Coefficient of Variation for Average Specific Growth Rates in The Control over The Study Duration.

Control replicate

Average specific growth rates over the study duration (day-1)

1

1.6225

2

1.6424

3

1.6376

Average specific growth rates over the study duration (day-1)

1.6342

sd for average specific growth rates over the study duration (day-1)

0.0104

%CV over study duration

0.6

Table 5. Cells Concentration, Yield of Biomass and Yield Inhibition, Growth Rate, and Growth Rate Inhibition of Cells Compares to the Control at 24, 48, and 72 Hours at Each Tested Concentration, in the Definitive Test.

Test period

(hours)

Nominal concentration

(mg/L)

Obs*

Cells concentration (cells/mL)

Cells concentration average

(cells/mL)

Yield (y)

(cells/mL)

Yield inhibition (Iy)

(%)

Growth rate (μ)

(day-1)

Growth rate inhibition (Iμ) (%)

R1

R2

R3

24

Control

NM

40000

40000

30000

36667

31667

0

1.9924

0

1

NM

40000

40000

30000

36667

31667

0

1.9924

0

3.2

NM

40000

40000

30000

36667

31667

0

1.9924

0

10

NM

30000

40000

40000

36667

31667

0

1.9924

0

32

NM

30000

20000

20000

23333

18333

42

1.5404

23

100

NM

10000

10000

10000

10000

5000

84

0.6931

65

48

Control

NM

200000

200000

220000

206667

201667

0

1.8608

0

1

NM

210000

170000

240000

206667

201667

0

1.8608

0

3.2

NM

180000

200000

240000

206667

201667

0

1.8608

0

10

NM

190000

170000

190000

183333

178333

12

1.8009

3

32

NM

100000

90000

100000

96667

91667

55

1.4809

20

100

NM

20000

10000

10000

13333

8333

96

0.4904

74

72

Control

NM

650000

690000

680000

673333

668333

0

1.6343

0

1

NM

680000

630000

700000

670000

665000

0

1.6326

0

3.2

NM

710000

640000

660000

670000

665000

0

1.6326

0

10

NM

580000

590000

680000

616667

611667

8

1.6050

2

32

NM

270000

250000

250000

256667

251667

62

1.3128

20

100

NM

20000

20000

20000

20000

15000

98

0.4621

72

R1, R2 and R3 = replicates

*NM = None morphological effects observed.

Validity criteria fulfilled:
yes
Conclusions:
According to OECD 201 test method, the 72h-ErC50 and the 72-EyC50 of Everzol SR98 was 61.75 mg/L and 25.86 mg/L respectively. The highest test substance concentration which no observed significant adverse effect (NOEC) on algal growth was 10mg/L and the lowest test substance concentration at which was observed significant reducing effect on growth (LOEC) was 32 mg/L.
Executive summary:

This test using the procedures outlined in the BIOAGRI Study Plan for 16264.202.078.17 and OECD 201 (OECD, 2011). The results of this OECD 201 test for Everzol SR98 show that test validity criteria was met.Under the test conditions,the 72h-ErC50 and the 72-EyC50 of Everzol SR98 was 61.75 mg/L and 25.86 mg/Lrespectively. The NOEC was 10mg/L and the LOEC was 32 mg/L.

Description of key information

Respectively,the 72h-ErC50 and the 72-EyC50 of Everzol SR98 was 61.75 mg/L and 25.86 mg/L for Pseudokirchneriella subcapitata (OECD TG201).

Key value for chemical safety assessment

EC50 for freshwater algae:
61.75 mg/L
EC10 or NOEC for freshwater algae:
10 mg/L

Additional information

The cell densitiesin the control have increased by an average factor of at least 16 within 2 days. The mean coefficient of variation for section-by-section specific growth rates in the control group were not exceed 35%. The coefficient of variation of average specific growth rates during the whole test period in replicate control groups were not exceed 7%. This test validity criteria was met. Under the test conditions,the 72h-ErC50 and the 72-EyC50 of Everzol SR98 was 61.75 mg/L and 25.86 mg/L respectively.