Fenitrothion

Short-term toxicity to fish

Administrative data

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

05 March 1987 - 09 March 1987

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1987

Report date:

1987

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EPA OPP 72-1 (Fish Acute Toxicity Test)

Version / remarks:

U.S. EPA FIFRA, 40 CFR, Part 158.145 Guideline 72-1 (1982)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Fenitrothion

EC Number:

204-524-2

EC Name:

Fenitrothion

Cas Number:

122-14-5

Molecular formula:

C9H12NO5PS

IUPAC Name:

O,O-dimethyl O-3-methyl-4-nitrophenyl phosphorothioate

Test material form:

liquid

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 60553
- Purity (measured): 94.5%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature Darkness
- Solubility and stability of the test substance in the solvent/vehicle: Stable during the 96 hrs test

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0.6, 1.2, 2.5, 5.0 and 10 mg/L (nominal conc.)
- Sampling method: 0hr and 96 hrs

Test solutions

Vehicle:

yes

Details on test solutions:

Stock solution:13.03g of Test substance dissolved in 100 mL of DMF aliqutted to different test media at different ration to achieve 0.6, 1.2, 2.5, 5.0 and 10 mg/L (nominal conc.). The measured concentrations yielded an average of 36 ± 14% of nominal at the 0-hour sampling (excluding the lowest exposure level affected by the diluter malfunction). The measured concentrations yielded an average of 39 ± 23% of nominal at the 96-hour sampling (excluding the lowest exposure level affected by the diluter malfunction).

Test organisms

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

TEST ORGANISM
-Common name: Bluegill Sunfish, Source: Osage Catfisheries, Inc. Osage Beach, Missouri Weight at study initiation (mean and range, SD): 3.8 g(+-0.98)
ACCLIMATION
-Acclimation conditions (same as test or not): 16:8 light dark cycle, 18 °C. Type and amount of food during acclimation: Brine shrimp daily. Feeding frequency during acclimation: daily. Acclimation period: 48 hrs starvation prior to test initiation,

Study design

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

none

Test conditions

Hardness:

225-275 CaCO3 equivalent ppb

Test temperature:

21°C

pH:

7.9-8.1

Dissolved oxygen:

6.8-8.1 mg/L (76%ASV- 90%ASV)

Nominal and measured concentrations:

Nominal concentration: 0.6, 1.2, 2.5, 5.0 and 10 mg/L Measured concentrations: 0.38, 0.69. 1.0, 1.2 and 6.4 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 30L
- Type (delete if not applicable): covered with lid
- Type of flow-through (e.g. peristaltic or proportional diluter): proportional diluter, intermittent dosing 9x1L/hr
- Renewal rate of test solution (frequency/flow rate): 7xreplacement using a diluter
- No. of organisms per vessel: 20
- No. of vessels per concentration (replicates): 1
- Biomass loading rate: 0.36/L/24hrs

TEST CONCENTRATIONS
- Spacing factor for test concentrations: Nominally 50% (this was not met due to diluter failiure and TS insolubility)
TEST SYSTEM
- Type of flow-through (e.g. peristaltic or proportional diluter): proportional diluter, intermittent dosing 9x1L/hr
- Renewal rate of test solution (frequency/flow rate): intermittent dosing 9x1L/hr 7 replacement per day
- No. of organisms per vessel: 20
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- No. of vessels per vehicle control (replicates):
- Biomass loading rate: 0.36/L/24hrs

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: well water
- Total organic carbon: 1.6ppm
- Alkalinity: 325-375ppm CaCO3


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

TEST CONCENTRATIONS
- Spacing factor for test concentrations: Nominally 50% (this was not met due to diluter failiure and TS insolubility)

- Justification for using less concentrations than requested by guideline:
- Range finding study
- Test concentrations:

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

2.5 mg/L

Nominal / measured:

meas. (arithm. mean)

Effect concentrations 2

Key result

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

0.69 mg/L

Nominal / measured:

meas. (arithm. mean)

Details on results:

Behavioural/sublethal effects noted at 6.4, 1.2, and 1.0mg/L during the study included loss of equilibrium and on bottom orientation. One fish died in each of the control and solvent control aquaria. This percentage of mortality in the controls did not comprise the toxicity results according to the criteria and was likely caused from handling stress during the assigment of fish to the test container. Given that mortality and/or behavioural/sublethal effects occurred at 6.4, 1.2, and 1.0mg/l, a no-effect concentration of fenitrothion toxicity to bluegill sunfish was determined to be 0.69 mg/l.

Any other information on results incl. tables

Sublethal observations / clinical signs:

Mortality and behavioural observations

 

Mean measured concentrations (Nominal concentrations) (mg/L)	No. of fish	24 hours		48 hours		72 hours		96 hours
		Cum. Mort.	Obs.	Cum. Mort.	Obs.	Cum. Mort.	Obs.	Cum. Mort.	Obs.
Control	20	0	19N 1LOE/OB	1	19N	1	19N	1	19N
Solvent control	20	0	20N	1	19N	1	19N	1	19N
1.0    (0.60)	20	0	20N	0	19N 1LOE/OB	1	19N	1	19N
0.38  (1.2)	20	0	20N	0	20N	0	20N	0	20N
0.69  (2.5)	20	0	20N	0	20N	0	20N	0	20N
1.2    (5.0)	20	1	19N	1	18N 1OB	1	18N 1OB	1	19N
6.4  (10)	20	17	3LOE	20	---	20	---	20	---

Cum. Mort.= Cumulative Mortality; Obs.= Observations

N= Normal; LOE= Loss of Equilibrium; OB= On Bottom Orientation

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Based on the mortality obtained from the Fenitrothion exposure range: 0.38, 0.69. 1.0, 1.2 and 6.4 mg/L (measured) (equivalent to 0.6, 1.2, 2.5, 5.0 and 10 mg/L (nominal conc.) the 96 hr LC50 value and 95% confidence interval was 2.5 mg/L (2.0 -3.2 mg/L) based on the average measured concentrations at 0 and 96 hrs. Behavior/sublethal effects occured at 6.4, 1.2 and 1.0 mg/L, a NOEC of Fenitrothion toxicity to bluegill sunfish was determined to be 0.69 mg/L. This conclusion was supported by the lack of mortality or behavioral/sublethal effects at and below the 0.69 mg/L test level.

Executive summary:

A 96 hour acute flow through toxicity study of Fenitrothion to bluegill sunfish (Lepomis macrochirus) was conducted. Twenty fish were used in each of five test concentrations plus Solvent Control and Well-water Control. The nominal dosing regime was 0.6, 1.2, 2.5, 5.0 and 10 mg/L based on 94.6% purity of Fenitrothion. Analytical measurements were made at 0 and 96 hrs. The measured concentrations were 0.38, 0.69. 1.0, 1.2 and 6.4 mg/L. The 96 hr LC50 value and 95% confidence interval was 2.5 mg/L (2.0 -3.2 mg/L) based on the average measured concentrations at 0 and 96 hrs. NOEC of Fenitrothion toxicity to bluegill sunfish was determined to be 0.69 mg/L. This conclusion was supported by the lack of mortality or behavioural/sublethal effects at and below the 0.69 mg/L and 0.38 mg/L test levels.