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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 March 09, 2018 to May 17, 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
GLP compliance:
yes
Test organisms (species):
Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)
Details on test organisms:
- Source (laboratory, culture collection): National Chiayi University Freshwater Bioresource Center
- Acclimation period: 2-4 days
Water media type:
freshwater
Total exposure duration:
72 h
Nominal and measured concentrations:
Nominal concentrations: 4.28, 9.41, 20.70, 45.54 and 100.20 mg/L
Details on test conditions:
- Test vessel: 125 mL glass flask
- Test volume: 60 mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3
- Light intensity and quality: 4440-8880 lux
Key result
Duration:
72 h
Dose descriptor:
EC50
Remarks:
ErC50
Effect conc.:
ca. 13.51 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: average specific growth rate
Duration:
72 h
Dose descriptor:
EC50
Remarks:
EyC50
Effect conc.:
ca. 3.56 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: yield

Table 1. The cell concentration for the definitive test

Group

(mg/L)

Cell concentration (×104cells/mL)

0 hour

24 ± 2 hours

48± 2 hours

72 ± 2 hours

Control groupa

0.00

1.00 ± 0.00

3.41 ± 0.17

8.29 ± 0.32

17.49 ± 0.69

Test group Aa

100.20

1.00 ± 0.00

1.62 ± 0.06

1.65 ± 0.06

2.09 ± 0.25

45.54

1.00 ± 0.00

1.59 ± 0.05

1.75 ± 0.05

2.20 ± 0.02

20.70

1.00 ± 0.00

1.83 ± 0.04

2.66 ± 0.31

6.31 ± 0.66

9.41

1.00 ± 0.00

1.88 ± 0.05

5.00 ± 1.05

10.58 ± 1.03

4.28

1.00 ± 0.00

2.02 ± 0.15

7.02 ± 0.16

9.61 ± 1.06

Test group Bb

100.20

1.00

1.87

3.65

15.6

45.54

1.00

1.96

4.85

11.19

20.70

1.00

2.17

5.27

15.28

9.41

1.00

2.09

4.84

17.59

4.28

1.00

2.00

7.76

17.91

a All of control group and test group A conducted three replicates, and the data showed as mean ± standard deviation.

b Test group B conducted one replicate.

 

Table 2. The average specific growth rate for the definitive test

Group

(mg/L)

Average specific growth rate (d-1)

0 ~ 24 ± 2

hour

24 ± 2 ~ 48 ± 2 hours

48 ± 2 ~ 72 ± 2 hours

0 ~ 72 ± 2

hours

Control groupa

0.00

1.22 ± 0.05

(4.15)

0.89 ± 0.09

(9.98)

0.75 ± 0.08

(10.40)

0.95 ± 0.01

(1.39)

Test group Aa

100.20

0.48 ± 0.03

(7.17)

0.02 ± 0.01

(45.26)

0.23 ± 0.09

(41.52)

0.24 ± 0.04*

(17.08)

45.54

0.47 ± 0.03

(6.88)

0.09 ± 0.02

(18.41)

0.23 ± 0.02

(10.72)

0.26 ± 0.00*

(0.88)

20.70

0.60 ± 0.02

(3.27)

0.37 ± 0.10

(27.32)

0.87 ± 0.04

(4.80)

0.61 ± 0.03*

(5.69)

9.41

0.63 ± 0.02

(3.82)

0.97 ± 0.19

(19.50)

0.76 ± 0.27

(35.59)

0.79 ± 0.03*

(4.03)

4.28

0.70 ± 0.07

(10.65)

1.25 ± 0.05

(4.11)

0.31 ± 0.09

(30.35)

0.75 ± 0.04*

(4.77)

Test group Ba

100.20

0.63

0.67

1.45

0.92

45.54

0.67

0.91

0.84

0.81

20.70

0.77

0.89

1.06

0.91

9.41

0.74

0.84

1.29

0.96

4.28

0.69

1.36

0.84

0.96

a All of control group and test group A conducted three replicates, and the data showed as mean ± standard deviation (Coefficient of variation [%]).

b Test group B conducted one replicate.

* SigmaStat 3.5 statistical software was used by One way ANOVA-Dunnett analysis, the results showed a significant difference between mean of the average specific growth rate of the test group A and the control group within 0~72± 2 hours (ρ< 0.05).

 

Table 3. The percent inhibition in average specific growth rate and percent inhibition of yield for the definitive test

Group

(mg/L)

Geometric mean conc. (mg/L)

Logarithm conc.

(mg/L)

Percent inhibition in average specific growth ratec(%)

Percent inhibition of yieldd(%)

Test group Aa

100.20

55.55

1.74

70.74

92.06

73.41

93.09

79.26

95.09

45.54

21.53

1.33

72.13

92.60

72.44

92.72

72.60

92.78

20.70

10.06

1.00

36.01

68.23

31.99

63.62

39.29

71.62

9.41

4.08

0.61

20.09

46.40

13.89

34.82

19.04

44.58

4.28

2.28

0.36

16.77

40.46

22.63

50.59

23.80

52.41

Test group Bb

100.20

55.55

1.74

3.99

11.48

45.54

21.53

1.33

15.60

38.22

20.70

10.06

1.00

4.71

13.42

9.41

4.08

0.61

-0.21

-0.59

4.28

2.28

0.36

-0.84

-2.53

a Test group A conducted three replicates.

b Test group B conducted one replicate.

c Percent inhibition in average specific growth rate (Ir) only within 0~72 ± 2 hours need to be calculated.

d Percent inhibition of yield (Iy) only within 0~72 ± 2 hours need to be calculated.

 

Table 4. ECX and 95% confidence interval for the definitive test

Parameter

ErC10a

ErC20

ErC50

EyC10b

EyC20

EyC50

ECX(mg/L)

1.88

3.08

13.51

0.38

0.66

3.56

95% confidence interval-lower

1.38

2.24

9.66

0.28

0.48

2.54

95% confidence interval-upper

2.58

4.26

19.08

0.52

0.91

5.04

a ErCx was calculated by percent inhibition in average specific growth rate.

b EyCx was calculated by percent inhibition of yield.

 

Table 5. The pH value for the definitive test

Group

(mg/L)

pH

0 hours

72 ± 2 hours

Control groupa

0.00

7.57 ± 0.12

7.58 ± 0.09

Test group Aa

100.20

7.50 ± 0.03

7.37 ± 0.03

45.54

7.41 ± 0.03

7.48 ± 0.06

20.70

7.60 ± 0.07

7.62 ± 0.12

9.41

7.43 ± 0.02

7.60 ± 0.07

4.28

7.57 ± 0.11

7.56 ± 0.09

Test group Ba

100.20

7.45

7.53

45.54

7.31

7.36

20.70

7.31

7.31

9.41

7.40

7.41

4.28

7.40

7.43

a All of control group and test group A conducted three replicates, and the data showed as mean ± standard deviation (Coefficient of variation [%]).

b Test group B conducted one replicate.

Validity criteria fulfilled:
yes
Conclusions:
According to OECD 201 test method, the ErC50 and the EyC50 of CR SB37 was 13.51 mg/L and 3.56 mg/L respectively.
Executive summary:

This test using the procedures outlined in the SuperLab Study Plan for M62-170900015001EN which is based on the SOP for the OECD 201 (SOPE-512) and referred to OECD 201 (OECD, 2011). The results of this test for CR SB37 show that test validity criteria was met. In the alga growth inhibition test (definitive test), the test article concentrations applied were 4.28, 9.41, 20.70, 45.54 and 100.20 mg/L. The alga growth would partially inhibited after CR SB37 shading of light, but less than toxicity of CR SB37. Therefore, the inhibition of algal growth was due to the toxicity of CR SB37. Under the test conditions, the ErC50and the EyC50of CR SB37 was 13.51 mg/L and 3.56 mg/L respectively.

Description of key information

Respectively, the ErC50 and the EyC50 of CR SB37 was 13.51 mg/L and 3.56 mg/L for Pseudokirchneriella subcapitata (OECD TG201).

Key value for chemical safety assessment

EC50 for freshwater algae:
13.51 mg/L

Additional information

The biomass in the control group have increased exponentially by a factor of at least 16 within the 72-hour test period. The specific growth rate in the control group was more than 0.92 d-1. The mean coefficient of variation for specific growth rates (0 ~ 24 ± 2 hour, 24 ± 2 ~ 48 ± 2 hours, 48 ± 2 ~ 72 ± 2 hours and 0 ~ 72 ± 2 hours) 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%. The variation in the pH values in the beginning and end of the tests was less than 1.5 units.Under the test conditions, the ErC50 and the EyC50 of CR SB37 was 13.51 mg/L and 3.56 mg/L respectively.