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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
Analysis of the test solution was performed, but it was not possible to differentiate from the background.
Qualifier:
according to
Guideline:
EPA OPP 122-2 (Algal Toxicity, Tiers I and II)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
Cell counts were made during the 96 h test. Temperature of the incubator was measured and recorded daily, and pH was detected in each test vessel at the beginning and end of the test.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Test type:
static
Water media type:
freshwater
Total exposure duration:
96 h
Test temperature:
24.5 - 25.3 °C
pH:
7.5 - 7.8
Nominal and measured concentrations:
Nominal concentrations used in the preliminary test:0.1, 1, 10, 100 and 1000 mg sodium chlorite/L(Doses are equivalent to 0.075, 0.75, 7.5, 75 and 750 mg chlorite/L)Nominal concentrations used in the actual test:Nominal concentrations were 0 (control), 0.62, 1.25, 2.5, 5.0 and 10.0 mg/L.(Doses are equivalent to 0, 0.46, 0.93, 1.87, 3.73 and 7.5 mg chlorite/L)
Reference substance (positive control):
no
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
8 other: mg sodium chlorite/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
6 other: mg chlorite/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
6.4 other: mg sodium chlorite/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
5 other: mg chlorite/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.2 other: mg sodium chlorite/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.15 other: mg chlorite/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
1 other: mg sodium chlorite/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% confidence interval of 0.62 t o1.25 mg/L
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
0.75 other: mg chlorite/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
Results of the preliminary test:After 96 h the number of cells / mL was less than 50 % of the control value at 10, 00 and 1000 mg/L sodium chlorite and greater than 50 % at all other concentrations.Results of the actual test:Exposure of the algae to sodium chlorite for 96 h resulted in a median effective concentration (EC50) of 1.0 mg/L with a 95% confidence interval of 0.62 to 1.25 mg/L (equivalent to 6 mg chlorite/L). No effects were noted.

Table A7_4_1_3(2)-5:        Cell concentration data

Number of cells/ml x 103

Nominal

Concentration

(mg sodium chlorite/L)

Replicate

0 h

24 h

48 h

72 h

96 h

0 (control)

1

10

42

100

346

1404

2

10

54

108

428

1744

3

10

46

132

446

1664

mean

10

47

113

407

1604

% control

100

100

100

100

100

0.62

1

10

44

104

358

1484

2

10

56

132

436

1852

3

10

40

110

412

1316

mean

10

47

115

402

1551

% control

100

100

102

99

97

1.25

1

10

42

92

156

274

2

10

36

96

236

631

3

10

34

110

190

576

mean

10

37

99

194

494

% control

100

79

88

48

31

2.5

1

10

40

108

228

364

2

10

32

112

182

326

3

10

34

92

176

296

mean

10

35

104

195

329

% control

100

74

92

48

20

5.0

1

10

44

90

108

138

2

10

22

80

122

212

3

10

32

54

60

116

mean

10

33

75

97

155

% control

100

70

66

24

10

10.0

1

10

16

30

12

16

2

10

24

26

24

14

3

10

18

16

18

12

mean

10

19

24

18

14

% control

100

40

21

4

1

Validity criteria fulfilled:
yes
Remarks:
(according to EU method C.3 the quality criteria are met: The cell density in the control cultures have increased by a factor of at least 16).
Conclusions:
Exposure of algae to sodium chlorite for 96 h resulted in a median EC50 of 1.0 mg/L, with a 95% confidence interval of 0.62 to 1.25 mg/L (equivalent to 0.75 mg chlorite/L)
Executive summary:

The aim of the study was to investigate the toxicity to aquatic algae due to the test material.

The test procedure used was EPA OPP 122-2 (Algal Toxicity, Tiers I and II).

Nominal concentrations used in the preliminary test: 0.1, 1, 10, 100 and 1000 mg sodium chlorite/L (Doses are equivalent to 0.075, 0.75, 7.5, 75 and 750 mg chlorite/L).

The result was as follows:

Exposure of algae to sodium chlorite for 96 h resulted in a median EC50 of 1.0 mg/L, with a 95% confidence interval of 0.62 to 1.25 mg/L (equivalent to 0.75 mg chlorite/L)

Description of key information

Key study. The test procedure used was EPA OPP 122-2 (Algal Toxicity, Tiers I and II). The result was as follows: Exposure of algae to sodium chlorite for 96 h resulted in a median EC50 of 1.0 mg/L, with a 95% confidence interval of 0.62 to 1.25 mg/L (equivalent to 0.75 mg chlorite/L

Key value for chemical safety assessment

EC50 for freshwater algae:
1 mg/L

Additional information

Key study. The test procedure used was EPA OPP 122-2 (Algal Toxicity, Tiers I and II). The result was as follows: Exposure of algae to sodium chlorite for 96 h resulted in a median EC50 of 1.0 mg/L, with a 95% confidence interval of 0.62 to 1.25 mg/L (equivalent to 0.75 mg chlorite/L)