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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

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
4.6 mg/L

Additional information

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