CJ303

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:

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):

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

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 (×10^4cells/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. EC_Xfor the limit test

Parameter	ECX (mg/L)
ErC10^a	46.88
ErC20	93.76
ErC50	>100.00
EyC10^b	16.87
EyC20	33.74
EyC50	84.36

^a E_rC_xwas calculated by percent inhibition in average specific growth rate.

^b E_yC_xwas 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 E_rC₅₀ of CJ303 forPseudokirchneriella subcapitatawas greater than 100.00 mg/L and E_yC₅₀ was 49.62 mg/L.

Description of key information

E_rC₅₀and the E_yC₅₀of 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 E_rC₅₀of CJ303 forPseudokirchneriella subcapitatawas greater than 100.00 mg/L and E_yC₅₀was 49.62 mg/L.