Sodium 2-biphenylate

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

15 - 19 Sep 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1075 (Freshwater and Saltwater Fish Acute Toxicity Test)

Version / remarks:

draft

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 1.0, 1.7, 2.9, 4.8 and 8.0 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 16 mg a.i./L diluter stock solution was prepared daily by dissolving approximately 2.1378 g (1.5281 gas active ingredient) of OPP/SOPP in 1 L of dilution water and diluting to a final volume of 95 L with dilution water. The resulting stock solution was observed to be clear and colorless with no visible undissolved test substance.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Common name: Rainbow trout
- Source: Osage Troutlodge, Inc., Sumner, Washington
- Length at study initiation (length definition, mean, range and SD): 36 mm (range: 33 to 39 mm); N = 30
- Weight at study initiation (mean and range, SD): 0.41 g (range: 0.33 to 0.51 g); N = 30

ACCLIMATION
- Acclimation period: 14 d
- Acclimation conditions (same as test or not): same
- Type and amount of food during acclimation: dry commercial flaked fish food (Ziegler Prime Flakes), ad libitum
- Feeding frequency during acclimation: daily except during the 48 hours prior to testing
- Health during acclimation (any mortality observed): Mortality <4.0%


FEEDING DURING TEST
The fish were not fed during the 96-hour definitive exposure

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

44 mg CaCO3/L

Test temperature:

13 - 14 °C

pH:

7.6 - 7.2

Dissolved oxygen:

9.7 - 7.8 mg/L

Nominal and measured concentrations:

Nominal concentrations: 1.0, 1.7, 2.9, 4.8 and 8.0 mg a.i./L
Mean measured concentrations: 0.68, 1.1, 2.1, 3.8 and 6.6 mg a.i./L (Percent of nominal: 68, 67, 73, 79 and 83%)

Details on test conditions:

TEST SYSTEM
- Test vessel: aquarium
- Type (delete if not applicable): open
- Material, sze, fill volume: glass, 30 (length) x 15 (width) x 20 (height) cm, 6.5 L
- Type of flow-through (e.g. peristaltic or proportional diluter): intermittent-flow proportional diluter (Mount and Brungs, 1967)
- Renewal rate of test solution (frequency/flow rate): 90% test solution replacement rate of approximately 9.0 hours
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: well water drawn from a 100-meter deep bedrock well
- Total organic carbon: 1.1 mg CaCO3/L
- Alkalinity: 30 mg/L

OTHER TEST CONDITIONS
- Photoperiod: 16 hours light and 8 hours darkness
- Light intensity: 620 to 1080 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Mortality and symptoms of intoxication after 0, 24, 48, 72 and 96 hours of exposure

TEST CONCENTRATIONS
- Range finding study: two range finding tests were performed: A 96-hour preliminary flow-through test and a 24-hour preliminary flow-through test
- Test concentrations:
First test (24 h flow through): 13, 22, 36, 60 and 100 mg a.i./L
Second test (24 h static): 0.010, 0.10 and 1.0 mg a.i./L.
Third test (24 h flow through): 1.3, 2.7, 3.6, 6.0 and 10 mg a.i./L
- Results used to determine the conditions for the definitive study:
First test (24 h flow through): 100% mortality in all treatments
Second test (24 h static): no mortality
Third test (96 h flow through): At 24 hours of exposure, 100% mortality at 6.0 and 10 mg a.i./L after 24 h, Following 96-hours of exposure, 33% mortality (one fish) was observed in the control. No mortality was observed in the 1.3, 2.7 and 3.6 mg a.i./L treatment levels. Two surviving fish exposed to the 3.6 mg a.i./L were observed to be on the bottom of the test vessel.

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

2.6 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% confidence interval:of 2.2 to 3.3 mg a.i./L

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

1.1 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

behaviour

Remarks:

physical effects

Details on results:

Following 24 h of exposure, 100% mortality was observed among fish exposed to the 6.6 mg a.i./L treatment level. Following 96 hours of exposure, 20 and 85% mortality was observed among fish exposed to the 2.1 and 3.8 mg a.i./L treatment levels, respectively. At test termination, all surviving fish exposed to the 3.8 mg a.i./L treatment level exhibited complete loss of equilibrium and were on the bottom of the test vessel. All surviving fish exposed to the 2.1 mg a.i./L treatment level exhibited darkened pigmentation, while one surviving fish exhibited complete loss of equilibrium and was on the bottom of the test vessel and one surviving fish was lethargic and on the bottom of the test vessel. No mortality or adverse effects were observed among fish exposed to the 1.1 mg a.i./L treatment level or the controls. Mortality of 10% was observed at the 0.68 mg a.i./L treatment level. Because the mortality observed at this treatment level was 1) observed in only one replicate vessel, 2) the test met the acceptable control mortality criterion of < 10%, and 3) since no mortality was observed in the next highest treatment level (1.1 mg a.i./L), this mortality was considered incidental and unrelated to treatment.

Reported statistics and error estimates:

Statistics were performed using a computer program (Stephan. 1982) comprising the statistical methods moving average angle analysis, probit analysis and binomial probability.

Sublethal observations / clinical signs:

Mean measured concentrations tested, corresponding mortalities and observations made during the 96-hour flow-through toxicity test exposing rainbow trout (Oncorhynchus mykiss) to OPP/SOPP.

Cumulative Percent Mortality (Number of Dead Fish^a)
Mean Measured Concentration [mg a.i./L]	Replicate	0-Hour	24 -Hour	48-Hour	72-Hour	96-Hour
Control	A	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	B	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	Mean	0	0	0	0	0
0.68	A	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	B	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	Mean	0	0	0	0	0
1.1	A	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	B	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	Mean	0	0	0	0	0
2.1	A	0 (0)	10 (1)	10 (1)	20 (2)	20 (2)
	B	0 (0)	10 (1)	10 (1)	10 (1)	20 (2)
	Mean	0	10^bc	10^cde	15^cf	20^bcg
3.8	A	0 (0)	70 (7)	70 (7)	70 (7)	80 (8)
	B	0 (0)	90 (9)	90 (9)	90 (9)	90 (9)
	Mean	0	80^h	80^h	80^h	85^h
6.6	A	0 (0)	100 (10)	100 (10)	100 (10)	100 (10)
	B	0 (0)	100 (10)	100 (10)	100 (10)	100 (10)
	Mean	0	100	100	100	100

    

a       Actual number of mortalities.

b       All surviving fish exhibited darkened pigmentation.

c       One surviving fish exhibited complete loss of equilibrium and was on the bottom of the test vessel.

d       Several surviving fish exhibited darkened pigmentation and were on the bottom of the test vessel.

e       Several surviving fish exhibited darkened pigmentation.

f       Two surviving fish were observed to be lethargic and on the bottom of the test vessel.

g       One surviving fish was observed to be lethargic and on the bottom of the test vessel.

h       All surviving fish exhibited complete loss of equilibrium and were on the bottom of the test vessel.

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

9 - 13 Sep 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1075 (Freshwater and Saltwater Fish Acute Toxicity Test)

Version / remarks:

draft

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 1.3, 2.7, 3.6, 6.0 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 20 mg a.i./L diluter stock solution was prepared prior to test initiation by dissolving approximately 2.6723 g (1.9102 gas active ingredient) of OPP/SOPP in 1 L of dilution water and diluting to a final volume of 95 L with dilution water. The resulting stock solution was observed to be clear and colorless with no visible undissolved test substance.

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

TEST ORGANISM
- Common name: bluegill
- Source: Osage Catfisheries, Osage Beach, Missouri
- Length at study initiation (length definition, mean, range and SD): 35 mm (range: 28 to 40 mm); N = 30
- Weight at study initiation (mean and range, SD): 0.56 g (range: 0.21 to 0.87 g); N = 30


ACCLIMATION
- Acclimation period: 14 d
- Acclimation conditions (same as test or not): same
- Type and amount of food during acclimation: dry commercial flaked fish food, ad libitum
- Feeding frequency during acclimation: daily except during the 48 hours prior to testing
- Health during acclimation (any mortality observed): no


FEEDING DURING TEST
The fish were not fed during the 96-hour definitive exposure

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

44 mg CaCO3/L

Test temperature:

21 to 23 °C

pH:

7.7 - 7.2

Dissolved oxygen:

8.9 - 7.4 mg/L

Nominal and measured concentrations:

Nominal concentrations: 1.3, 2.7, 3.6, 6.0 and 10 mg a.i./L
Mean measured concentrations: 0.79, 1.7, 2.6, 4.6 and 8.0 mg a.i./L (Percent of nominal: 61, 65, 72, 77 and 80%)

Details on test conditions:

TEST SYSTEM
- Test vessel: aquarium
- Type (delete if not applicable): open
- Material, size, fill volume: glass, 30 (length) x 15 (width) x 20 (height) cm, 6.5 L
- Type of flow-through (e.g. peristaltic or proportional diluter): intermittent-flow proportional diluter (Mount and Brungs, 1967)
- Renewal rate of test solution (frequency/flow rate): 90% test solution replacement rate of approximately 9.0 hours
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: well water drawn from a 100-meter deep bedrock well
- Total organic carbon: 1.1 mg/L
- Alkalinity: 30 mg CaCO3/L


OTHER TEST CONDITIONS
- Photoperiod: 16 hours light and 8 hours darkness
- Light intensity: 530 to 1100 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Mortality and symptoms of intoxication after 0, 24, 48, 72 and 96 hours of exposure

TEST CONCENTRATIONS
- Range finding study: two range finding tests were performed: A 96-hour preliminary flow-through test and a 24-hour preliminary flow-through test
- Test concentrations:
(96 h flow through): 1.3, 2.7, 3.6, 6.0 and 10 mg a.i./L
- Results used to determine the conditions for the definitive study: 100% mortality at conctnration 10 mg a.i./L, 10% mortality at 6 mg a.i./L, Surviving fish exposed to the 6.0 mg a.i./L treatment level exhibited a complete loss of equilibrium and were on the bottom of the test vessel at test termination.

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

5.1 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% confidence interval: 2.6 to 8.0 mg a.i./L

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

2.6 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

behaviour

Remarks:

physical effects

Details on results:

Following 24 hours of exposure, 100% mortality was observed among fish exposed to the highest treatment level tested (8.0 mg a.i./L). After 96 hours of exposure, 35% mortality was observed among fish exposed to the 4.6 mg a.i./L treatment level. Surviving fish exposed to the 4.6 mg a.i./L treatment level exhibited a complete loss of equilibrium and were on the bottom of the test vessel at test termination. No mortality or adverse effects were observed among fish exposed to the remaining treatment levels tested (0. 79, 1.7 and 2.6 mg a.i./L) or the control.

Reported statistics and error estimates:

Statistics were performed using a computer program (Stephan. 1982) comprising the statistical methods moving average angle analysis, probit analysis and binomial probability.

Sublethal observations / clinical signs:

Mean measured concentrations tested, corresponding mortalities and observations made during the 96-hour flow-through toxicity test exposing Bluegill Sunfish (Lepomis macrochirus) to OPP/SOPP.

Cumulative Percent Mortality (Number of Dead Fish^a)
Mean Measured Concentration [mg a.i./L]	Replicate	0-Hour	24 -Hour	48-Hour	72-Hour	96-Hour
Control	A	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	B	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	Mean	0	0	0	0	0
1.6	A	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	B	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	Mean	0	0	0	0	0
3.3	A	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	B	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	Mean	0	0	0	0	0
6.7	A	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	B	0 (0)	0(0)	0(0)	0(0)	0(0)
	Mean	0	0	0	0	0
12	A	0 (0)	0 (0)	0 (0)	30 (3)	50 (5)
	B	0 (0)	0 (0)	0 (0)	10 (1)	20 (2)
	Mean	0	0^bc	0^d	20^d	35^d
20	A	0 (0)	100 (10)	100 (10)	100 (10)	100 (10)
	B	0 (0)	100 (10)	100 (10)	100 (10)	100 (10)
	Mean	0	100	100	100	100

a              Actual number of mortalities.

b             One fish exhibited a partial loss of equilibrium and was on the bottom of the test vessel.

c             Several fish exhibited a complete loss of equilibrium and were on the bottom of the test vessel..

d              All fish exhibited a complete loss of equilibrium and were on the bottom of the test vessel.

Reference 3

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

29 Sep - 3 Oct 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1075 (Freshwater and Saltwater Fish Acute Toxicity Test)

Version / remarks:

draft

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 3.2, 5.4, 9.0, 15 and 25 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 50 mg a.i./L diluter stock solution was prepared by dissolving approximately 6.6807 g (4.7750 gas active ingredient) of OPP/SOPP in 2 L of 20‰ seawater and diluting to a final volume of 95 L with dilution water. The resulting stock solution was observed to be clear and colorless with no visible undissolved test substance.

Test organisms (species):

Cyprinodon variegatus

Details on test organisms:

TEST ORGANISM
- Common name: sheepshead minnow
- Source: Aquatic Biosystems, Fort Collins, Colorado, USA
- Length at study initiation (length definition, mean, range and SD): 27 mm (range: 20 to 34 mm); N = 30
- Weight at study initiation (mean and range, SD): 0.42 g (range: 0.22 to 0.74 g); N = 30


ACCLIMATION
- Acclimation period: 14 d
- Acclimation conditions (same as test or not): same
- Type and amount of food during acclimation: brine shrimp, ad libitum,
- Feeding frequency during acclimation: daily except during the 48 hours prior to testing
- Health during acclimation (any mortality observed): no mortality observed


FEEDING DURING TEST
The fish were not fed during the 96-hour definitive exposure

Test type:

flow-through

Water media type:

saltwater

Limit test:

no

Total exposure duration:

96 h

Test temperature:

22 to 23 °C

pH:

7.9 to 8.1

Dissolved oxygen:

7.4 - 4.6 mg/L

Salinity:

20 to 21‰

Nominal and measured concentrations:

Nominal concentrations: 3.2, 5.4, 9.0, 15 and 25 mg a.i./L
Mean measured concentrations: 1.6, 3.3, 6.7, 12 and 20 mg a.i/L (Percent of nominal: 52, 62, 75, 78 and 80%)

Details on test conditions:

TEST SYSTEM
- Test vessel: aquarium
- Type (delete if not applicable): open
- Material, size, fill volume: glass, 30 (length) x 15 (width) x 20 (height) cm, 6.8 L
- Type of flow-through (e.g. peristaltic or proportional diluter): intermittent-flow proportional diluter (Mount and Brungs, 1967)
- Renewal rate of test solution (frequency/flow rate): 90% test solution replacement rate of approximately 9.0 hours
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: natrual seawater from the Cape Cod Canal, Bourne, Massachusetts
- Total organic carbon: < 2.0 mg/L


OTHER TEST CONDITIONS
- Photoperiod: 16 hours light and 8 hours darkness
- Light intensity: 530 to 1200 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Mortality and symptoms of intoxication after 0, 24, 48, 72 and 96 hours of exposure

TEST CONCENTRATIONS
- Range finding study: two range finding tests were performed: A 96-hour preliminary flow-through test and a 24-hour preliminary flow-through
- Test concentrations:
first test (96 h flow through): 1.0, 1.7, 2.9, 4.8 and 8.0 mg a.i./L
second test (24 h flow through): 25 mg a.i./L
- Results used to determine the conditions for the definitive study: First test (96 h flow through): no mortality or adverse effects were observed second test (24 h flow through): 100% mortality

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

5.1 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% confidence interval: 3.3 to 6.7 mg a.i./L

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

3.3 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

behaviour

Remarks:

physical effects

Details on results:

At test termination, one surviving fish exposed to the 6.7 mg a.i./L treatment level exhibited partial loss of equilibrium, lethargy and was on the bottom of the test vessel, while one fish exhibited partial loss of equilibrium, lethargy and was on the surface of the test solution. No adverse effects were observed among fish exposed to the 1.6 and 3.3 mg a.i./L treatment levels or the control.

Reported statistics and error estimates:

Statistics were performed using a computer program (Stephan. 1982) comprising the statistical methods moving average angle analysis, probit analysis and binomial probability.

Sublethal observations / clinical signs:

Mean measured concentrations tested, corresponding mortalities and observations made during the 96-hour flow-through toxicity test exposing sheepshead minnow (Cyprinodon variegatus) to OPP/SOPP.

Cumulative Percent Mortality (Number of Dead Fish^a)
Mean Measured Concentration [mg a.i./L]	Replicate	0-Hour	24-Hour	48-Hour	72-Hour	96-Hour
Control	A	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	B	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	Mean	0	0	0	0	0
1.6	A	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	B	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	Mean	0	0	0	0	0
3.3	A	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	B	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	Mean	0	0	0	0	0
6.7	A	0 (0)	100 (10)	100 (10)	100 (10)	100 (10)
	B	0 (0)	80 (8)	80 (8)	80 (8)	80 (8)
	Mean	0^b	90^cd	90^e	90^f	90^gh
12	A	0 (0)	100 (10)	100 (10)	100 (10)	100 (10)
	B	0 (0)	100 (10)	100 (10)	100 (10)	100 (10)
	Mean	0^ijk	100	100	100	100
20	A	0 (0)	100 (10)	100 (10)	100 (10)	100 (10)
	B	0 (0)	100 (10)	100 (10)	100 (10)	100 (10)
	Mean	0^ic	100	100	100	100

a             Actual number of mortalities.

b             One surviving fish exhibited partial loss of equilibrium

c             One surviving fish exhibited complete loss of equilibrium and was on the surface of the test solution.

d             One surviving fish exhibited complete loss of equilibrium and was on the bottom of the test vessel.

e             Two surviving fish exhibited complete loss of equilibrium and were on the bottom of the test vessel.

f              Two surviving fish exhibited partial loss of equilibrium, were lethargic and were on the bottom of the test vessel.

g             One surviving fish exhibited partial loss of equilibrium, was lethargic and was on the bottom of the test vessel.

h             One surviving fish exhibited partial loss of equilibrium, was lethargic and was on the surface of the test solution

i              Several surviving fish exhibited complete loss of equilibrium and were on the bottom of the test vessel.

j              Several surviving fish exhibited complete loss of equilibrium and were on the surface of the test solution.

k             Several surviving fish were lethargic and on the bottom of the test vessel.

Description of key information

LC50 (96 h): 2.6 mg a.i./L (measured, arithm. mean)

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

2.6 mg/L

Additional information

Three guideline studies investigating the acute toxicity of sodium 2-biphenylate (CAS 132-27-4) to three different fish species are available. All three available studies followed draft guideline EPA OPPTS 850.1075 in accordance with GLP. The studies were assessed in a weight of evidence approach.

In the first study the acute toxicity of sodium 2-biphenylate to Oncorhynchus mykiss was investigated in a flow-through test at nominal substance concentrations of 1.0, 1.7, 2.9, 4.8 and 8.0 mg a.i./L. The test solutions were replaced at a rate of 90% every 9 hours. The test substance concentration was analytically verified at test initiation and test termination. The mean measured concentrations were 0.68, 1.1, 2.1, 3.8 and 6.6 mg a.i./L (68, 67, 73, 79 and 83% of nominal). Based on the arithmetic-. mean meas. concentrations a LC50 (96 h) of 2.6 mg a.i./L was determined (Hoberg, 2006a).

The toxic range was confirmed by a comparable test was conducted using Lepomis macrochirus as test organism. The study was set up as a flow-through test. The fish were exposed to nominal concentrations of 1.3, 2.7, 3.6, 6.0 and 10 mg a.i./L at a renewal rate of 90% every 9 hours. The mean measured test concentrations based analytical verification at test start and test termination were 0.79, 1.7, 2.6, 4.6 and 8.0 mg a.i./L (61, 65, 72, 77 and 80% of nominal). The recorded LC50 (96 h) was 5.1 mg a.i./L (arithmetic mean meas.) (Hoberg, 2006b).

The third study investigated the acute toxicity of sodium 2-biphenylate to the saltwater species Cyprinodon variegatus in a flow-through test. The tested nominal substance concentrations were 3.2, 5.4, 9.0, 15 and 25 mg a.i./L. Analytical test substance verification at test start and test terminations determined mean measured concentrations of 1.6, 3.3, 6.7, 12 and 20 mg a.i/L (52, 62, 75, 78 and 80% of nominal). The determined LC50 (96 h) based on the arith.mean meas. concentrations was 5.1 mg a.i./L (Hoberg, 2006c).

The lowest freshwater and marine water LC50 values of 2.6 mg a.i./L and 5.1 mg a.i./L respectively were considered relevant for hazard assessment.