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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Refer to the section 13 for details on the read across justification. The algae study with the read across substance is considered sufficient to fulfil the information requirements as further explained in the provided endpoint summary.
Reason / purpose for cross-reference:
reference to other study
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
414 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
512 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
598 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
126 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
232 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
334 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Details on results:
See below table.

Table 1: Number of cells per mL x 104

 

48 h

72 h

96 h

 

1

2

3

1

2

3

1

2

3

Control

55

43

45

131

110

128

292

280

252

x

48

123

270

180 ppm

26

28

35

117

123

140

310

320

268

x (%I)

30 (38%)

127 (0%)

299 (0%)

320 ppm

39

38

36

90

121

104

220

280

312

x (%I)

38 (22%)

105 (15%)

270 (0%)

560 ppm

40

40

15

80

65

88

180

182

174

x (%I)

32 (35%)

78 (37%)

179 (34%)

1,000 ppm

Less than 10

No viable cells

No viable cells

x (%I)

>79%

100%

100%

1,800 ppm

No viable, countable cells

Repeat: 1,000 ppm confirmed lack of growth confirmed

Note: Inoculum of 1 x104cells/mL at "0" time; cell counts at 24 h recorded as less than 10x104for all flasks. Cell growth was insufficient at 24 h to establish concentration effect relationships for all concentrations and for the blank control. The median effect, therefore, could not be calculated for that period.

x- Mean

%I - percent inhibition relative to control per time period

pH =pH of all flasks ranged 6.4 - 6.7, including control at start and finish of test.

As indicated by the calculated correlation coefficient above, the better estimate of the median algal inhibitory concentration was derived from 72 - 96 h data. This was due to more developed cell growth with time and thus better enumeration and differentiation among test concentrations

Validity criteria fulfilled:
yes
Conclusions:
Based on the results of the read across study, the 72 h EbC50 and NOEC of the test substance in Selenastrum capricornutum are 512 and 232 mg/L respectively.
Executive summary:

A study was conducted to evaluate the toxicity of the read across substance, methyl carbamate, to algae Selenastrum capricornutum under static conditions according to OECD Guideline 201, in compliance with GLP. On basis of preliminary range finding study, test concentrations were selected and test organisms were exposed to 0, 180, 320, 560, 1,000 and 1,800 ppm (i.e., equivalent to 0, 180, 320, 560, 1,000 and 1,800 mg/L) in 3 replicates per concentration. Incubation was done at 21 – 22C in a shaking culture. Cell growth was insufficient at 24 h to establish concentration effect relationships for all concentrations and for the blank control. The median effect, therefore, could not be calculated for that period. Due to more developed cell growth with time and thus better enumeration and differentiation among test concentrations, the better estimate of the median algal inhibitory concentration was derived from 72 - 96 h data. All the validity criteria were met in this test. Percent growth was plotted versus log of concentration. Linear regression analysis was used to calculate EbC50 and NOEC. Under the study conditions, the 48 h, 72 h and 96 h EbC50 of test substance for Selenastrum capricornutum were 414, 512 and 598 mg/L. The 48 h, 72 h and 96 h NOEC for effect on algal growth was determined to be 126, 232 and 334 mg/L (Drozdowski D, 1987).

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From December 4, 1986 to December 8, 1986
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
- Name of test material (as cited in study report): CT-258-86
- Description: White crystalline solid
- Storage conditions: In original container, ambient conditions
Analytical monitoring:
no
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Organism:Selenastrum capricornutum
- Strain no. 22662
- Source: American type culture collection
Test type:
static
Total exposure duration:
96 h
Test temperature:
21 - 22°C
pH:
6.4 - 6.7
Nominal and measured concentrations:
0, 180, 320, 560, 1,000 and 1,800 ppm
Details on test conditions:
TEST SYSTEM
- Test vessel: 250 mL glass capped flasks
- Initial cells density: 1x10^4 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3
- Shaking culture was used for incubation

GROWTH MEDIUM
- Standard medium used: Sterile OECD Algal Medium (100 mL/flask)

Special Preparation/ Precautions:
(1)Sample diluted in distilled water v/v was stored in dark until used.
(2)Test concentration was established with pipettes and direct addition of dilutions

OTHER TEST CONDITIONS
- Photoperiod: continuous light
- Light intensity: 8000 lux
Reference substance (positive control):
no
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
414 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: Correlation coefficient r^2 = 0.69
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
512 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: Correlation coefficient r^2 = 0.89
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
598 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: Correlation coefficient r^2 = 0.97
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
126 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: Correlation coefficient r^2 = 0.69
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
232 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: Correlation coefficient r^2 = 0.89
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
334 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: Correlation coefficient r^2 = 0.97

Table 1: Number of cells per mL x 104

 

48 h

72 h

96 h

 

1

2

3

1

2

3

1

2

3

Control

55

43

45

131

110

128

292

280

252

x

48

123

270

180 ppm

26

28

35

117

123

140

310

320

268

x (%I)

30 (38%)

127 (0%)

299 (0%)

320 ppm

39

38

36

90

121

104

220

280

312

x (%I)

38 (22%)

105 (15%)

270 (0%)

560 ppm

40

40

15

80

65

88

180

182

174

x (%I)

32 (35%)

78 (37%)

179 (34%)

1,000 ppm

Less than 10

No viable cells

No viable cells

x (%I)

>79%

100%

100%

1,800 ppm

No viable, countable cells

Repeat: 1,000 ppm confirmed lack of growth confirmed

Note: Inoculum of 1 x104 cells/mL at "0" time; cell counts at 24 h recorded as less than 10x104 for all flasks. Cell growth was insufficient at 24 h to establish concentration effect relationships for all concentrations and for the blank control. The median effect, therefore, could not be calculated for that period.

x- Mean

%I - percent inhibition relative to control per time period

pH =pH of all flasks ranged 6.4 - 6.7, including control at start and finish of test.

As indicated by the calculated correlation coefficient above, the better estimate of the median algal inhibitory concentration was derived from 72 - 96 h data. This was due to more developed cell growth with time and thus better enumeration and differentiation among test concentrations

Validity criteria fulfilled:
yes
Conclusions:
The 48 h, 72 h and 96 h EbC50 of test substance for Selenastrum capricornutum were 414, 512 and 598 ppm. The 48 h, 72 h and 96 h NOEC for effect on algal growth was determined to be 126, 232 and 334 ppm.
Executive summary:

A study was conducted to evaluate the toxicity of the test substance to algae Selenastrum capricornutum under static conditions according to OECD Guideline 201, in compliance with GLP. On basis of preliminary range finding study, test concentrations were selected and test organisms were exposed to 0, 180, 320, 560, 1,000 and 1,800 ppm (i.e., equivalent to 0, 180, 320, 560, 1,000 and 1,800 mg/L) in 3 replicates per concentration. Incubation was done at 21 – 22C in a shaking culture. Cell growth was insufficient at 24 h to establish concentration effect relationships for all concentrations and for the blank control. The median effect, therefore, could not be calculated for that period. Due to more developed cell growth with time and thus better enumeration and differentiation among test concentrations, the better estimate of the median algal inhibitory concentration was derived from 72 - 96 h data. All the validity criteria were met in this test. Percent growth was plotted versus log of concentration. Linear regression analysis was used to calculate EbC50 and NOEC. Under the study conditions, the 48 h, 72 h and 96 h EbC50 of test substance for Selenastrum capricornutum were 414, 512 and 598 mg/L. The 48 h, 72 h and 96 h NOEC for effect on algal growth was determined to be 126, 232 and 334 mg/L (Drozdowski D, 1987).

Description of key information

Based on the read across study to methyl carbamate, the 72 h EbC50 for effect on algal growth due to the test substance was determined to be 512 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
512 mg/L
EC10 or NOEC for freshwater algae:
232 mg/L

Additional information

A study was conducted to evaluate the toxicity of the read across substance, methyl carbamate, to algae Selenastrum capricornutum under static conditions according to OECD Guideline 201, in compliance with GLP. On basis of preliminary range finding study, test concentrations were selected and test organisms were exposed to 0, 180, 320, 560, 1,000 and 1,800 ppm (i.e., corresponding to 0, 180, 320, 560, 1,000 and 1,800 mg/L nominal concentrations) in 3 replicates per concentration. Incubation was done at 21 – 22⁰C in a shaking culture. No analytical monitoring was carried out. Cell growth was insufficient at 24 h to establish concentration effect relationships for all concentrations and for the blank control. The median effect, therefore, could not be calculated for that period. Due to more developed cell growth with time and thus better enumeration and differentiation among test concentrations, the better estimate of the median algal inhibitory concentration was derived from 72 - 96 h data. All the validity criteria were met in this test. Percent growth was plotted versus log of concentration. Linear regression analysis was used to calculate EbC50 and NOEC. Under the study conditions, the 48 h, 72 h and 96 h EbC50 of the test substance for inhibition of Selenastrum capricornutum growth were 414, 512 and 598 mg/L. The respective 48 h, 72 h and 96 h NOEC for effect on algal growth was determined to be 126, 232 and 334 mg/L (Drozdowski D, 1987).