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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 May 16, 2016 to November 19, 2018
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)
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
1. Preparation of alga solution: According to OECD 201:2011, initial biomass of Pseudokirchneriella subcapitata was 1 x 10^4 cells/mL and must conduct acclimated culture to ensure it reached exponential growth in 2-4 days before the test start.
2. Preparation of test article: CJ303 was prepared and dissolved by medium.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
- Source (laboratory, culture collection): National Chiayi University Freshwater Bioresource Center
- Acclimation period: 2-4 days

Culture conditions:
1. Temperature: 21-24℃ and the temperature constant within ±2℃ between culture period.
2. Light intensity: Wavelength from the range of 400-700nm. The light intensity rom the range of 4440-8880 lux. The light intensity should be maintained within ±15%.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Test temperature:
21-24℃ and the temperature constant within ±2℃ between culture period.
Details on test conditions:
- Test vessel: 125 mL glass flask
- Test volume: 60 mL
- Type of cover: sealed with silicone plugs
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6
- Light intensity and quality: Wavelength from the range of 400-700nm. The light intensity rom the range of 4440-8880 lux. The light intensity should be maintained within ±15%.
- Shaking rate: 100 ± 10 rpm.
Duration:
72 h
Dose descriptor:
EC50
Remarks:
ErC50
Effect conc.:
> 100 mg/L
Duration:
72 h
Dose descriptor:
EC50
Remarks:
EyC50
Effect conc.:
49.62 mg/L

Table 1. The algal biomass for the limit test

Group

(mg/L)

Mean of algal biomass (×104cells/mL) ± standard deviation

Day 0

Day 1

Day 2

Day 3

Control group

0.00

1.00 ± 0.00

5.65 ± 0.47

23.22 ± 2.63

63.45 ± 2.97

Test group

100.00

1.00 ± 0.00

4.53 ± 0.40

14.43 ± 2.41

26.43 ± 4.03

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

Group

(mg/L)

Mean of average specific growth rate (d-1) ± standard deviation

(Coefficient of variation [%])

Day 0-1

Day 1-2

Day 2-3

Day 0-3

Control group

0.00

1.73 ± 0.09

(4.99)

1.471 ± 0.07

(5.27)

1.01 ± 0.07

(7.09)

1.38 ± 0.02

(1.16)

Test group

100.00

1.51 ± 0.09

(5.86)

1.15 ± 0.13

(11.75)

0.61 ± 0.12

(20.09)

1.09 ± 0.05*

(4.93)

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

Group

(mg/L)

Logarithm of concentration

(mg/L)

Percent inhibition in average specific growth rate (%)

Percent inhibition of yield (%)

100.00

2.00

18.08

53.66

19.25

55.93

18.43

54.36

26.16

67.32

26.41

67.67

19.66

56.70

Table 4. ECXfor the limit test

Parameter

ECX

(mg/L)

ErC10a

46.88

ErC20

93.76

ErC50

>100.00

EyC10b

16.87

EyC20

33.74

EyC50

84.36

a ErCxwas calculated by percent inhibition in average specific growth rate.

b EyCxwas calculated by percent inhibition of yield

Table 5. The pH value for the limit test

Group

(mg/L)

Mean of pH value ± standard deviation

Day 0

Day 3

Control group

0.00

7.99 ± 0.03

8.51 ± 0.11

Test group

100.00

7.84 ± 0.10

7.99 ± 0.07

Validity criteria fulfilled:
yes
Conclusions:
According to OECD 201 test method, the ErC50 and the EyC50 of CJ303 was >100 mg/L and 49.62 mg/L respectively.
Executive summary:

An alga growth inhibition test was conducted according to OECD 201:2011 to evaluate growth inhibition caused by CJ303. The test system was Pseudokirchneriella subcapitata. According to OECD201:2011, the concentration series should cover the range causing 5-75% inhibition of alga growth rate. If there was no growth inhibition occurred at 100 mg/L, the highest concentration was 100 mg/L. In the range-finding test, the test article concentration of 100.00-0.16 mg/L was used which covered a range of -4.07~1.16% inhibition in average specific growth rate, so the limit test was conducted. In the limit test, the test article concentrations applied was 100.00 mg/L. The results showed that, in days 0-3, the percent inhibition in average specific growth rate was a range of 18.08~26.41%, and the percent inhibition of yield was a range o 53.66~67.67%. Therefore, under these test conditions, the ErC50 of CJ303 forPseudokirchneriella subcapitatawas greater than 100.00 mg/L and EyC50 was 49.62 mg/L.

Description of key information

ErC50and the EyC50of CJ303 was >100 mg/L and 49.62 mg/L for Pseudokirchneriella subcapitata, respectively (OECD TG201).

Key value for chemical safety assessment

EC50 for freshwater algae:
100 mg/L

Additional information

An alga growth inhibition test was conducted according to OECD 201:2011 to evaluate growth inhibition caused by CJ303. The test system wasPseudokirchneriella subcapitata. According to OECD201:2011, the concentration series should cover the range causing 5-75% inhibition of alga growth rate. If there was no growth inhibition occurred at 100 mg/L, the highest concentration was 100 mg/L. In the range-finding test, the test article concentration of 100.00-0.16 mg/L was used which covered a range of -4.07~1.16% inhibition in average specific growth rate, so the limit test was conducted. In the limit test, the test article concentrations applied was 100.00 mg/L. The results showed that, in days 0-3, the percent inhibition in average specific growth rate was a range of 18.08~26.41%, and the percent inhibition of yield was a range o 53.66~67.67%. Therefore, under these test conditions, the ErC50of CJ303 forPseudokirchneriella subcapitatawas greater than 100.00 mg/L and EyC50was 49.62 mg/L.