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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Qualifier:
no guideline followed
Principles of method if other than guideline:
Animals from commercial supplier acclimated in 100% dilution water. Temperature 18.2 - 19.0 ºC. Dissolved oxygen maintained above 6.9 mg/L. Fed once or twice daily before test. Static screening test was followed by flow-through test. Test temperature was 18 ± 1 ºC with five concentrations of test substance and a dilution water control. Twenty amphipods equally distributed among 2 replicates of each treatment. Concentrations monitored every 24 hours with HPLC. Used computer program to calculate LC50.
GLP compliance:
yes
Analytical monitoring:
yes
Vehicle:
no
Details on test solutions:
Stock solution was used; 40.8 g of test substance was dissolved in deionized water and diluted to 1000 mL.
Test organisms (species):
Gammarus fasciatus
Details on test organisms:
TEST ORGANISM
- Common name: amphipod
- Source: Aquatic Research Organisms division of Resource Analysts, Inc.
- Feeding during test: no food 48 h prior and during the test
- Average wet weight (blotted dry): 0.02 g

ACCLIMATION
- Acclimation period: more than 14 days
- Acclimation conditions : in 100% dilution water, in glass aquarium, under flow-through conditions, temp 18.2-10 ºC, DO above 6.9 mg/L
- Type and amount of food: Tetra-min dry fish food
- Feeding frequency: once or twice daily
- Health during acclimation (any mortality observed): free of apparent sickness, injury and abnormalities

Test type:
flow-through
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
96 h
Test temperature:
17.1 - 18.5 ºC
pH:
8.2 -8.4
Dissolved oxygen:
8.5 - 9.0 mg/L
Nominal and measured concentrations:
Nominal: 0, 3.6, 6.0, 9.6, 14.4, 24.0 mg/L
Measured: ND, 3.8, 5.3, 8.5, 13.0, 23.4 mg/L
- static screening test used nominal concentrations: 0.2, 2.0, 20, 200, and 2000 mg/L
- flow-through screening test used nominal concentrations 3.6 and 24.0 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 4 Liter glass vessels
- Aeration: no
- Type of flow-through (e.g., peristaltic or proportional diluter): intermittent flow proportional diluter
- Renewal rate of test solution (frequency/flow rate): 16.1 volume exchanges per test vessel per day
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 1
- Biomass loading rate: 0.08 g/L


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: well water collected at EnviroSystems in Hampton, New Hampshire
- adjusted to hardness of 160 mg/L as CaCO3
- stored in 500-gallon polyethylene tanks and aerated
- Total organic carbon: <1.0 mg/L
- TSS: <10 mg/L
- Pesticides: Not detected
- Conductivity: 1200 micromhos/cm

OTHER TEST CONDITIONS
- Photoperiod: 16 h light/ 8 h dark
- Type: cool white fluorescent light
- Light intensity: 10 uEs-1m-2

TEST CONCENTRATIONS
- static screening test used nominal concentrations: 0.2, 2.0, 20, 200, and 2000 mg/L
- flow-through screening test used nominal concentrations 3.6 and 24.0 mg/L
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
4.6 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
mortality
Remarks on result:
other: 95% CL 4.3 - 5.1 mg/L
Duration:
72 h
Dose descriptor:
LC50
Effect conc.:
5.5 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
mortality
Remarks on result:
other: 95% CL 4.9-6.3 mg/L
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
7.8 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
mortality
Remarks on result:
other: 95% CL 6.8-8.8 mg/L
Duration:
24 h
Dose descriptor:
LC50
Effect conc.:
> 23.4 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
mortality
Details on results:
- amphipods exposed to 13 mg/L were lethargic and those exposed to 23.4 mg/L were immobilized at 24 hours
- all surviving amphipods exposed to 8.5 mg/L were lethargic at 48 hours and immobilized at 72 hours
- 8 of the 12 surviving amphipods exposed to 5.3 mg/L were immobilized at 72 hours and all survivors were immobilized at 96 hours
- Any observations (e.g., precipitation) that might cause a difference between measured and nominal values: no insoluble material was observed.

Affected/Survival (%)

 

0 hr

24 hr

48 hr

72 hr

96 hr

Measured Concentration (mg/L)

Rep 1

Rep 2

Rep 1

Rep 2

Rep 1

Rep 2

Rep 1

Rep 2

Rep 1

Rep 2

ND

0/100

0/100

0/100

0/100

0/100

0/100

0/100

0/100

0/100

0/90

3.8

0/100

0/100

0/100

0/90

0/100

0/90

0/90

0/90

0/90

0/90

5.3

0/100

0/100

0/90

0/100

0/90

0/100

40/40

40/80

10/10

30/30

8.5

0/100

0/100

0/100

0/90

60/60

30/30

10/10

-

-

-

13

0/100

0/100

100/100

90/90

-

-

-

-

-

-

23.4

0/100

0/100

100/100

90/90

-

-

-

-

-

-

Dashes represent vessels with no surviving amphipods. Affected amphipods exposed to 13.0 mg/L were lethargic and those exposed to 23.4 mg/L were immobilized. All surviving amphipods exposed to 8.5 mg/L were affected at 48 hours and immobilized at 72 hours. Affected amphipods exposed to 5.3 mg/L were immobilized.

Validity criteria fulfilled:
yes
Conclusions:
Exposure of amphipods to the test substance resulted in a 96 h LC50 of 4.6 mg/L, with 95% confidence interval of 4.3 - 5.1 mg/L.
Executive summary:

Exposure of amphipods to the test substance resulted in a 96 hour LC50 of 4.6 mg/L, with a 95 percent confidence interval of 4.3 - 5.1 mg/L.

Static range test produced 100% survival at 0.2 and 2.0 mg/L and 0% survival at all higher tested concentrations. Test was performed under unaerated, flow through conditions with 5 concentrations at 18 ºC. Amphipods were acclimated for more than 14 days. Amphipods exposed to 13 mg/L were lethargic and those exposed to 23.4 mg/L were immobilized at 24 hours. All surviving amphipods exposed to 8.5 mg/L were lethargic at 48 hours and immobilized at 72 hours. Eight of the 12 surviving amphipods exposed to 5.3 mg/L were immobilized at 72 hours and all survivors were immobilized at 96 hours.

Description of key information

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
4.6 mg/L

Additional information