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Short-term toxicity to fish

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Reference
Endpoint:
short-term toxicity to fish
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Remarks:
The bioassay procedures generally followed the techniques recommended in Standard Methods, APHA.
Qualifier:
equivalent or similar to guideline
Guideline:
other: Standard Methods for the Examination of Water and Wastewater, 13th Edition, 1971, Published by APHA, AWWA, and WPCF.
Guideline:
other: Biological water Quality Committee, "ORSANCO 24-hour Bioassay Procedures", 1973.
GLP compliance:
no
Analytical monitoring:
not specified
Vehicle:
no
Test organisms (species):
Pimephales promelas
Details on test organisms:
TEST ORGANISM
- Common name: Fathead minnows
- Length at study initiation (length definition, mean, range and SD): 2.5 to 5 cm
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Hardness:
30 - 60 mg/L
Test temperature:
71 - 76 Deg. F
pH:
7.2 - 7.6
Dissolved oxygen:
7.5 to 9.0 mg/L
Nominal and measured concentrations:
10 to 10,000 mg/L
Details on test conditions:
Initial toxicity testing (Range finding):
The initial toxicity testing involved the use of range-finding procedures which used 2 fish in 1.5 liters of dilution water. A broad range (10 to 10,000 mg/L) of test concentrations was set up in about 5 wide mouth half-gallon bottles prior to the introduction of the fish. The test period was about 24 hours under conditions of controlled aeration.

Definitive tests:
Definitive test was performed using 18.5 liters of dilution water with 10 fish per test vessel under minimal controlled aeration. Dissolved oxygen concentration was maintained above 5 mg/L through the test duration of 96 hours.
Reference substance (positive control):
not specified
Duration:
24 h
Dose descriptor:
LC50
Effect conc.:
51 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
24 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Key result
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
23 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality (fish)

Description of key information

The 96-h LC50 value is 23 mg/L in freshwater fish (P. promelas).

Key value for chemical safety assessment

Additional information

A static acute aquatic toxicology test was performed to determine definitive 96 hr LC50 value, by following Standard Methods for the Examination of Water and Wastewater, APHA and procedures obtained from a research committee. Fresh water fish, Pimephales promelas (Fathead minnows) measuring 2.5 to 5 cm were exposed to different concentrations of isobutyraldehyde. Fish survival and physical response, as well as temperature, pH and dissolved oxygen levels, were monitored daily during the test period of 96 hours. Fresh water was used as dilution water which had pH of 7.2 to 7.6, temperature ranging 71 to 76 Deg. F, total hardness of 30 to 60 mg/L and dissolved oxygen concentration of 7.5 to 9.0 mg/l. The dilution water was carbon treated to remove chlorine and pH adjusted by the addition of acid or base. Range-finding test was performed as initial toxicity test with 2 fish in 1.5 liters of dilution water. The test period was 24 hours under the conditions of controlled aeration using broad range (10 to 10,000 mg/l) of product concentrations. Definitive test was performed using 18.5 liters of dilution water with 10 fish per test vessel under minimal controlled aeration. Dissolved oxygen concentration was maintained between 7.5 to 9.0 mg/l through the test duration of 96 hours. 96-h LC50 values of isobutyraldehyde to Pimephales promelas (Fathead minnows) were found to be 51, 24 and 23 mg/l after 24, 48 and 96 hours, respectively.

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