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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Qualifier:
according to guideline
Guideline:
EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II) (January 2012)
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 0.5, 1.0, 2.0, 4.0, 8.0 mg a.i./L
- Sampling time: at 0, 72 and 96 hours
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): Acetone
- Concentration of vehicle in test medium: 0.01% v/v
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: green alga
- Strain: UTEX 1648
- Source: Department of Botany, University of Texas, USA
- Age of inoculum (at test initiation): 3 - 7 days
- Method of cultivation: cultured in freshwater algal nutrient medium under continuous illumination of approx. 4300 Lux at a temperature of 24 ± 2 °C.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Test temperature:
24 ± 2 °C
pH:
After 0 hours: 7.4 - 7.5
After 72 hours: 7.7 -8.1
Nominal and measured concentrations:
Nominal test concentrations: 0.5, 1.0, 2.0, 4.0 and 8.0 mg a.i./L
Mean measured concentrations (72 h, % of nominal): 86 - 94
Mean measured concentrations (96 h, % of nominal): 83 - 89
Details on test conditions:
TEST SYSTEM
- Test vessel: 250 ml Erlenmeyer flasks containing 100 ml test solution
- Initial cells density: 10 000 cells/ml
- Control end cells density: 57E+04 cells/ml after 72 h; 147E+04 after 96 hours
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3
- No. of vessels per vehicle control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Test medium was freshwater algal nutrient medium (FWAM), prepared by the addition of appropriate reagent nutrients to ABC reagent water

OTHER TEST CONDITIONS
- Photoperiod: permanent
- Light intensity and quality: cool-white fluorescent lightning, 4300 ± 430 lux

EFFECT PARAMETERS MEASURED: cell densities after 24, 48, 72 and 96 hours
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.468 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
3.57 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
1.35 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
0.432 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
3.78 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
1.32 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Validity criteria fulfilled:
yes
Executive summary:

The study from Hicks (2002) was conducted according to OECD 201 and revealed a EC50 (72 h) of 3.57 mg/L for the growth rate of Selenastrum capricornutum. The NOEC (72 h) is 0.468 mg/L.

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:
Please refer to analogue justification provided in IUCLID section 13
Reason / purpose for cross-reference:
read-across source
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.468 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
3.57 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
1.35 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
0.432 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
3.78 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
1.32 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
13 - 22 Feb 2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II) (January 2012)
Version / remarks:
draft
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 0.0098, 0.039, 0.16, 0.63, 2.5 and 10 mg a.i./L measured at test initiation and termination
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A 10 mg a.i./L stock solution was prepared prior to test initiation by placing 0.0141 g (0.0101 g as active ingredient) of OPP/SOPP in a 1000 mL volumetric flask and bringing it to volume with sterile AAP medium. The resulting stock solution was observed to be clear and colorless with no visible undissolved test substance. The test concentrations were prepared separately by dilution of the stock solution.
Test organisms (species):
Anabaena flos-aquae
Details on test organisms:
TEST ORGANISM
- Common name: blue green algae
- Strain: strain 1444
- Source (laboratory, culture collection): bred at testing facility (originally obtained from University of Texas, Austin, Texas; USA
- Method of cultivation: a shaking rate of 100 ± 10 rpm, a temperature of 24 ± 2 °C and continuous illumination at the surface of the medium with an intensity range of 150 to 250 footcandles (1600 to 2700 lux). Lighting was supplied by Premira VitaLux® fluorescent bulbs. Culture flasks were agitated continuously on an orbital shaker

The inoculum used to initiate the toxicity test with OPP/SOPP was taken from a stock culture that had been transferred to fresh medium seven days before testing.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Test temperature:
22 - 23 °C
pH:
6.8 - 7.8
Conductivity:
90 μmhos/cm
Nominal and measured concentrations:
Nominal test substance concentrations: 0.0098, 0.039, 0.16, 0.63, 2.5 and 10 mg a.i./L
Mean measured test substance concentrations: 0.0052, 0.034, 0.15, 0.59, 2.4 and 9.6 mg a.i./L (Percent of nominal: 53, 87, 94, 93, 96, 96)
Details on test conditions:
TEST SYSTEM
- Test vessel: 20 mL flasks
- Type (delete if not applicable): covered with stainless steel caps permitting gas exchange
- Fill volume: 100 mL
- Initial cells density: 10000 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Algal Assay Procedure (AAP) medium

OTHER TEST CONDITIONS
- Photoperiod: continuous illumination
- Light intensity and quality: 1600 to 2700 lux, 30 to 60 μE/m2/S

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: hemacytometer (Neubauer Improved) every 24 hours

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 0.010, 0.10, 1.0, 10 and 100 mg a.i./L
- Results used to determine the conditions for the definitive study: cell densities in the 0.010, 0.10, 1.0, 10 and 100 mg a.i./L treatment levels averaged 9, 7.25, 8, 0 and 0E4 cells/mL, respectively.
Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
5.9 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: Confidence interval: 5.3 - 6.6 mg a.i./L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
2.4 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
4 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Remarks on result:
other: Confidence interval: 1.4 - 5.4 mg a.i./L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
2.4 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
2.3 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
other: Cell density
Details on results:
The 0- to 72-hour growth rate in the control averaged 1.08 days-1. The 0- to 72-hour growth rate in the 0.0052, 0.034, 0.15, 0.59, 2.4 and 9.6 mg a.i./L treatment levels averaged 1.08, 1.16, 1.13, 1.12, 1.06 and 0.02 days-1, respectively. Based on the results of Shapiro-Wilks' and Bartlett's Tests, this data set passed the requirements for normality and homogeneity of variance, therefore, Williams' Test was used to determine treatment-related effects. A significant reduction in growth rate was determined in the 9.6 mg a.i./L treatment level as compared to the control data, therefore the 72-hour NOEC was determined to be 2.4 mg a.i./L. The 72-hour ErC50 (corresponding 95% confidence limits) was calculated to be 5.9 mg a.i./L (5.3 to 6.6 mg a.i./L).
Reported statistics and error estimates:
The data were first checked for normality using Shapiro-Wilks' Test (Weber et al., 1989) and for homogeneity of variance using Bartlett's Test (Horning and Weber, 1985). If the data sets passed the tests for homogeneity and normality, then Williams' Test (Williams, 1971, 1972) was used to determine the NOEC. If the data did not pass the tests for homogeneity and normality, then Kruskal-Wallis' Test was used to determine the NOEC. All statistical determinations were made at the 95% level of certainty, except in the case of Shapiro-Wilks' and Bartlett's Tests, where the 99% level of certainty was applied. TOXSTAT® Version 3.5 (Gulley et al., 1996) was used to perform these calculations.

Calculated biomass (area under the growth curve) of Anabaena flosaquae after 72 hours of exposure to OPP/SOPP.

Mean Measured Concentration [mg a.i./L]

 Total Biomass (mean of 3 replicates) [104 cells/mL] after 72 h  Percent Inhibition
 Control  25.33  n.a.
 0.0052  23.83  6
 0.034  28.01  -11
 0.15  26.82  -6
 0.59  20.78  18
 2.4  16.61  34
 9.6  -0.04  100

Calculated growth rates of Anabaena flos-aquae after 72 hours of exposure to OPP/SOPP.

Mean Measured Concentration [mg a.i./L]

 Growth Rate (days-1) 

(mean of 3 replicates)

 Percent Inhibition
 Control  1.08  n.a.
 0.0052

 1.08

 0

 0.034

 1.16

 -7

 0.15

1.13

 -5

 0.59

 1.12

 -4

 2.4

 1.06

 2

 9.6

0.02

 98

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
22 September to 2 October 2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II) (January 2012)
Version / remarks:
draft
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 0.0098, 0.039, 0.16, 0.63, 2.5 and 10 mg a.i./L measured at test initiation and termination
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A 10 mg a.i./L stock solution was prepared prior to test initiation by placing 0.0141 g (0.0101 g as active ingredient) of OPP/SOPP in a 1000-mL volumetric flask and bringing it to volume with sterile AAP medium. The resulting stock solution was observed to be clear and colorless with no
visible undissolved test substance. The test concentrations were prepared separately by dilution of the stock solution.
Test organisms (species):
Navicula pelliculosa
Details on test organisms:
TEST ORGANISM
- Common name: diatom
- Strain: strain 667
- Source (laboratory, culture collection): bred at testing facility (originally obtained from University of Texas, Austin, Texas; USA
- Method of cultivation: a shaking rate of 100 ± 10 rpm, a temperature of 24 ± 2 °C and continuous illumination at the surface of the medium with an intensity range of 150 to 250 footcandles (1600 to 2700 lux). Lighting was supplied by Premira VitaLux® fluorescent bulbs. Culture flasks were agitated continuously on an orbital shaker.

The inoculum used to initiate the toxicity test with OPP/SOPP was taken from a stock culture that had been transferred to fresh medium six days before testing.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Test temperature:
24 °C
pH:
7.2 - 9.1
Conductivity:
90 - 100 μmhos/cm
Nominal and measured concentrations:
Nominal test substance concentrations: 0.0098, 0.039, 0.16, 0.63, 2.5 and 10 mg a.i./L
Mean measured test substance concentrations: 0.0089, 0.035, 0.15, 0.59, 2.4 and 9.6 mg a.i./L (Percent of nominal: 91, 91, 93, 94, 96, 96)
Details on test conditions:
TEST SYSTEM
- Test vessel: 20 mL flasks
- Type (delete if not applicable): covered with stainless steel caps permitting gas exchange
- Fill volume: 100 mL
- Initial cells density: 10000 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Algal Assay Procedure (AAP) medium


OTHER TEST CONDITIONS
- Photoperiod: continuous illumination
- Light intensity and quality: 3900 to 4700 lux, 51 to 75 μE/m2/S

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: hemacytometer (Neubauer Improved) every 24 hours

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 0.0010, 0.010, 0.10, 1.0, 10 and 100 mg a.i./L
- Results used to determine the conditions for the definitive study: cell densities in the 0.0010, 0.010, 0.10, 1.0, 10 and 100 mg a.i./L treatment levels averaged 44, 44, 20, 28, 3.0 and 0.38 x E4 cells/mL, respectively
Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
5.7 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: Confidence interval: 5.4 - 6.0 mg a.i./L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.59 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
2.8 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Remarks on result:
other: Confidence interval: 2.1 - 3.8 mg a.i./L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.59 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
1.9 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
other: Cell density
Details on results:
The 0- to 72-hour growth rate in the control averaged 1.32 days·'. The 0-to 72-hour growth rate in the 0.0089, 0.035, 0.15, 0.59, 2.4 and 9.6 mg a.i./L treatment levels averaged 1.17, 1.33, 1.20, 1.29, 1. 14 and 0.08 days-', respectively. Based on the results of Shapiro-Wilks' and Bartlett's Tests, this data set passed the requirements for normality and homogeneity of variance, therefore, Williams' Test was used to determine treatment-related effects. A significant reduction in growth rate was determined in the 2.4 and 9.6 mg a.i./L treatment levels as compared to the control data.
Reported statistics and error estimates:
The data were first checked for normality using Shapiro-Wilks' Test (Weber et al., 1989) and for homogeneity of variance using Bartlett's Test (Horning and Weber, 1985). If the data sets passed the tests for homogeneity and normality, then Williams' Test (Williams, 1971, 1972) was used to determine the NOEC. If the data did not pass the tests for homogeneity and normality, then Kruskal-Wallis' Test was used to determine the NOEC. All statistical determinations were made at the 95% level of certainty, except in the case of Shapiro-Wilks' and Bartlett's Tests, where the 99% level of certainty was applied. TOXSTAT® Version 3.5 (Gulley et al., 1996) was used to perform these calculations.

Calculated biomass (area under the growth curve) of Navicula pelliculosa after 72 hours of exposure to OPP/SOPP.

Mean Measured Concentration [mg a.i./L]

 Total Biomass (mean of 3 replicates) [104 cells/mL] after 72 h  Percent Inhibition
 Control  40.51  n.a.
 0.0089  25.33  37
 0.035  39.97  1
 0.15 27.98  31
 0.59  38.51  5
 2.4  21.50  47
 9.6  -0.57  101

Calculated growth rates of Navicula pelliculosa after 72 hours of exposure to OPP/SOPP

Mean Measured Concentration [mg a.i./L]

 Growth Rate (days-1) 

(mean of 3 replicates)

 Percent Inhibition
 Control  1.32  n.a.
 0.0089

 1.17

 11

 0.035

 1.33

 -1

 0.15

1.20

 9

 0.59

 1.29

 2

 2.4

 1.14

 14

 9.6

0.08

 94

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
29 Sep - 12 Oct 200 2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II) (January 2012)
Version / remarks:
draft
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 0.0024, 0.0098, 0.039, 0.16, 0.63, 2.5 and 10 mg a.i./L measured at test initiation and termination
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A 10 mg a.i./L stock solution was prepared prior to test initiation by placing 0.0142 g (0.0102 g as active ingredient) of OPP/SOPP in a 1000-mL volumetric flask and bringing it to volume with sterile AES medium. The resulting stock solution was observed to be clear and colorless with no
visible undissolved test substance. The test concentrations were prepared separately by dilution of the stock solution.
Test organisms (species):
Skeletonema costatum
Details on test organisms:
TEST ORGANISM
- Common name: diatom
- Strain: strain 667
- Source (laboratory, culture collection): bred at testing facility (originally obtained from Bigelow Laboratories,West Boothbay Harbor. Maine, USA)
- Method of cultivation: a shaking rate of 100 ± 10 rpm, a temperature of 24 ± 2 °C and continuous illumination at the surface of the medium with an intensity range of 150 to 250 footcandles (1600 to 2700 lux). Lighting was supplied by Premira VitaLux® fluorescent bulbs. Culture flasks were agitated continuously on an orbital shaker

The inoculum used to initiate the toxicity test with OPP/SOPP was taken from a stock culture that had been transferred to fresh medium six days before testing.
Test type:
static
Water media type:
saltwater
Limit test:
no
Total exposure duration:
96 h
Test temperature:
20 to 21 °C
pH:
7.9 - 8.8
Salinity:
30 ± 2 g/L
Conductivity:
38000 - 40000 μmhos/cm
Nominal and measured concentrations:
Nominal test substance concentrations: 0.0024, 0.0098, 0.039, 0.16, 0.63, 2.5 and 10 mg a.i./L
Mean measured test substance concentrations: 0.0019, 0.0071, 0.034, 0.15, 0.60, 2.4 and 9.8 mg a.i./L (Percent of nominal: 80, 72, 88, 91, 94, 95, 98)
Details on test conditions:
TEST SYSTEM
- Test vessel: 20 mL flasks
- Type (delete if not applicable): covered with stainless steel caps permitting gas exchange
- Fill volume: 100 mL
- Initial cells density: 77000 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Artificially Enriched Seawater (AES) medium prepared with sterile, filtered. natural seawater


OTHER TEST CONDITIONS
- Photoperiod: 14 hours light and 10 hours darkness
- Light intensity and quality: 3900 to 4700 lux, 65 to 80 μE/m2/S

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: hemacytometer (Neubauer Improved) every 24 hours

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 0.010, 0.10, 1.0, 10 and 100 mg a.i./L
- Results used to determine the conditions for the definitive study: cell densities in the 0.010, 0.10, 1.0, 10 and 100 mg a.i./L treatment levels averaged 72, 60, 51, 3 and 0 x E4 cells/mL, respectively
Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
7.4 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: Confidence interval: 7.0 - 7.7 mg a.i./L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
2.4 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
6.2 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Remarks on result:
other: Confidence interval: 4.8 - 6.8 mg a.i./L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
2.4 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
6.4 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
other: Cell density
Details on results:
The 0- to 72-hour growth rate in the 0.0019, 0.0071, 0.034, 0.15. 0.60, 2.4 and 9.8 mg a.i./L treatment levels averaged 0.69, 0.74, 0.69, 0.71, 0.75, 0.73 and 0.19 days -1, respectively. Based on the results of Shapiro-Wilks' and Bartlett's Tests, this data set passed the requirements for normality and homogeneity of variance, therefore, Williams' Test was used to determine treatment-related effects. A significant reduction in growth rate was determined in the 9.8 mg a.i./L treatment level as compared to the control data, therefore, the72-hour NOEC was determined to be 2.4 mg a.i./L.
Reported statistics and error estimates:
The data were first checked for normality using Shapiro-Wilks' Test (Weber et al., 1989) and for homogeneity of variance using Bartlett's Test (Horning and Weber, 1985). If the data sets passed the tests for homogeneity and normality, then Williams' Test (Williams, 1971, 1972) was used to determine the NOEC. If the data did not pass the tests for homogeneity and normality, then Kruskal-Wallis' Test was used to determine the NOEC. All statistical determinations were made at the 95% level of certainty, except in the case of Shapiro-Wilks' and Bartlett's Tests, where the 99% level of certainty was applied.
TOXSTAT® Version 3.5 (Gulley et al., 1996) was used to perform these calculations.

Calculated biomass (area under the growth curve) of Skeletonema costatum after 72 hours of exposure to OPP/SOPP.

Mean Measured Concentration [mg a.i./L]

 Total Biomass (mean of 3 replicates) [104 cells/mL] after 72 h  Percent Inhibition
 Control  62.59  n.a.
 0.0019  83.72  -34
 0.0071  68.39  -9
 0.034 60.25  4
 0.15  57.03  9
0.60  71.38  .14
 2.4  59.92  4
 9.8  14.08  78

Calculated growth rates of Skeletonema costatum after 72 hours of exposure to OPP/SOPP

Mean Measured Concentration [mg a.i./L]

 Growth Rate (days-1) 

(mean of 3 replicates)

 Percent Inhibition
 Control  0.67  n.a.
 0.0019

 0.69

 -3

 0.0071

 0.74

 -10

 0.034

0.69

 -3

 0.15

 0.71

 -6

 0.60

 0.75

 -12

 2.4

0.73

 -9

 9.8  0.19  72

Description of key information

ErC50 (72 h): 3.57 mg a.i./L (measured, arithm. mean); read across

NOErC (72 h): 0.468 mg a.i./L (measured, arithm. mean); read across

Key value for chemical safety assessment

EC50 for freshwater algae:
3.57 mg/L
EC10 or NOEC for freshwater algae:
0.468 mg/L

Additional information

Studies investigating the toxicity of sodium 2-biphenylate (CAS 132-27-4) to standard organisms are not available. The assessment was therefore based on a study conducted with the analogue substance 2-phenylphenol (CAS 90-43-7) as part of a read across approach, which is in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5. Further justification is given within the overall summary chapter 6.1 and within the analogue justification in IUCLID section 13.

The effect of 2-phenylphenol (CAS 90-43-7) on the freshwater algae Pseudokirchneriella subcapitata was tested in a guideline study following OECD 201 with GLP compliance (Hicks, 2002). The algal growth was observed for 72 hours at nominal test concentrations of 0.5, 1.0, 2.0, 4.0 and 8.0 mg a.i./L. Measured concentrations, sampled at test start and test end, ranged from 72 to 103% of the nominal concentration during the test. Based on growth rate, the 72-hour ErC50value was 3.57 mg a.i./L (arith.mean meas.). The determined NOErC (72 h) was 0.468 mg a.i./L (arith.mean meas.).

The data is supported by three studies on the target substance sodium 2-biphenylate (CAS 132-27-4) conducted according to EPA OPPTS 850.5400 with GLP compliance.

In one of the supporting studies the acute toxicity of sodium 2-biphenylate to the blue-green algae Anabaena flos-aquae was investigated at nominal substance concentrations of 0.0098, 0.039, 0.16, 0.63, 2.5 and 10 mg a.i./L. The test substance concentration was analytically verified at test initiation and test termination. The mean measured concentrations were 0.0052, 0.034, 0.15, 0.59, 2.4 and 9.6 mg a.i./L (53, 87, 94, 93, 96, and 96% of nominal). Based on the growth rate an ErC50 (72 h) of 5.9 mg a.i./L (arithmetic mean meas.) was determined.The reported NOErC (72 h) is 2.4 mg a.i./L (arith.mean meas.) (Hoberg, 2006e). 

A further study performed according to EPA OPPTS 850.5400 investigated the effect of sodium 2-biphenylate on the freshwater diatomNavicula pelliculosa.The diatoms were exposed to nominal concentrations of 0.0098, 0.039, 0.16, 0.63, 2.5 and 10 mg a.i./L The mean measured test concentrations based on analytical verification at test start and test termination were 0 0.0089, 0.035, 0.15, 0.59, 2.4 and 9.6 mg a.i./L (91, 91, 93, 94, 96 and 96% of nominal). The recorded ErC50 (72 h) was 5.7 mg a.i./L (arith. mean meas.) based on the growth rate.The reported NOErC (72 h) is 0.59 mg a.i./L (arith. mean meas.) (Hoberg, 2006f).

The third study investigated the toxicity of sodium 2-biphenylate to the marine diatom Skeletonema costatum. The tested nominal substance concentrations were 0.0024, 0.0098, 0.039, 0.16, 0.63, 2.5 and 10 mg a.i./L. Analytical test substance verification at test start and test terminations determined mean measured concentrations of 0.0019, 0.0071, 0.034, 0.15, 0.60, 2.4 and 9.8 mg a.i./L(80, 72, 88, 91, 94, 95 and 98 % of nominal). Based on the growth rate the determined ErC50 (72 h) was 7.4 mg a.i./L (arith. mean meas.). The reported NOErC (72 h) is 2.4 mg a.i./L (arith. mean meas.) (Hoberg, 2006g).