Methomyl

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

fish early-life stage toxicity

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPP 72-4 (Fish Early Life-Stage and Aquatic Invertebrate Life-Cycle Studies)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Methomyl technical
DPX-X1179-512
Purity: 98.6%

Analytical monitoring:

yes

Vehicle:

yes

Remarks:

water

Test organisms (species):

Cyprinodon variegatus

Test type:

flow-through

Water media type:

saltwater

Limit test:

yes

Total exposure duration:

36 d

Test temperature:

29.0 and 31.0°C

pH:

7.6 to 8.2

Dissolved oxygen:

6.3 to 8.0 mg/L

Salinity:

15 to 16 parts per thousand

Nominal and measured concentrations:

Nominal: 0, 0.066, 0.13, 0.25, 0.50, and 1.0 mg/L
Measured: 0, 0.066, 0.13, 0.26, 0.49, and 1.0 mg/L

Reference substance (positive control):

no

Key result

Duration:

36 d

Dose descriptor:

other: MATC

Effect conc.:

0.36 mg/L

Key result

Duration:

36 d

Dose descriptor:

NOEC

Effect conc.:

0.26 mg/L

Key result

Duration:

36 d

Dose descriptor:

LOEC

Effect conc.:

0.49 mg/L

Details on results:

Exposure of embryonic, larval, and juvenile sheepshead minnows to the test substance for 36 days resulted in a LOEC of 0.49 mg/L, a NOEC of 0.26 mg/L, and a MATC of 0.36 mg/L. The most sensitive measured biological endpoints were the mean wet weight and total length of surviving fish.

Validity criteria fulfilled:

yes

Conclusions:

36 day MATC = 0.36 mg/L
36 day NOEC = 0.26 mg/L
36 day LOEC = 0.49 mg/L

Executive summary:

The early life stage toxicity of the test substance to the sheepshead minnow,Cyprinodon variegatus, was conducted for 36 days according to EPA OPP 72-4. The test was performed under flow-through, unaerated conditions with five concentrations of test substance (0.066, 0.13, 0.25, 0.50, and 1.0 mg/L) and a dilution water control. Mean measured concentrations were ND (not detected at or above the limit of quantitation of 0.010 mg/L; control), 0.066, 0.13, 0.26, 0.49, and 1.0 mg/L, and concentrations were stable throughout the test. Mean measured concentrations were used for the calculations of the no observed effect concentration (NOEC), lowest observed effect concentration (LOEC), and maximum acceptable toxicant concentration (MATC).

 

Exposure of embryonic, larval, and juvenile sheepshead minnows to the test substance for 36 days resulted in a LOEC of 0.49 mg/L, a NOEC of 0.26 mg/L, and a MATC of 0.36 mg/L. The most sensitive measured biological endpoints were the mean wet weight and total length of surviving fish.

Reference 2

Endpoint:

fish life cycle toxicity

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPP 72-5 (Fish Life Cycle Toxicity)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Methomyl technical
DPX-X1179-394
Purity: 98.35%

Analytical monitoring:

yes

Vehicle:

yes

Remarks:

water

Test organisms (species):

Pimephales promelas

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

193 d

Hardness:

142 - 168 mg/L (as CaCO3)

Test temperature:

Growth aquarium: 24.2-25.3°C; Spawning aquaria: 24.6-25.2°C

pH:

7.63-8.39

Dissolved oxygen:

4.7-7.9 (first 56 days); Days 70-98: 4.5-6.0; Days 140 to termination (last set of F1 generation juveniles): 4.5-8.0; From day 112 to termination (parental generation): 5.0-7.5 mg/L

Conductivity:

326 - 438 µS

Nominal and measured concentrations:

Nominal: 0, 19, 38, 75, 150, 300 µg/L
Measured: 0, 18.8, 40,7, 76,0, 142, and 280 µg/L

Reference substance (positive control):

no

Key result

Duration:

193 d

Dose descriptor:

other: MATC

Effect conc.:

104 µg/L

Basis for effect:

growth rate

Key result

Duration:

193 d

Dose descriptor:

NOEC

Effect conc.:

76 µg/L

Key result

Duration:

193 d

Dose descriptor:

LOEC

Effect conc.:

142 µg/L

Details on results:

Parental generation egg hatchability and survival were significantly reduced at the 142 and/or 280 µg/L test concentrations. Parental generation growth, as measured by standard length at 28, 56, and 84 days post-hatch, showed a statistically significant reduction relative to the control after exposure to 142 and 280 µg/L. Growth, as measured by wet weight, exhibited a significant reduction after 84 days of exposure to 280 µg/L.

F1 generation hatchability, calculated from day 2, was not significantly reduced at any test concentration. F1 generation survival, after 56 days of growth, was not significantly reduced at any test concentration. F1 generation growth, as measured by standard length at 56 days post-hatch, showed a statistically significant reduction after exposure to 142 and 280 µg/L. Growth, as measured by blotted wet weight at 56 day post-hatch, exhibited a significant reduction after exposure to 280 µg/L.

Validity criteria fulfilled:

yes

Conclusions:

MATC = 104 µg/L (based on the most sensitive endpoint - growth)
NOEC = 76.0 µg/L
LEC = 142 µg/L

Executive summary:

A flow-through full life cycle toxicity study with the fathead minnow was conducted according to EPA guideline OPP 72-5 at dose levels of 0, 18.8, 40,7, 76,0, 142, and 280 µg/L. The maximum acceptable toxicant concentration (MATC) was calculated.

Parental generation egg hatchability and survival were significantly reduced at the 142 and/or 280 µg/L test concentrations. Parental generation growth, as measured by standard length at 28, 56, and 84 days post-hatch, showed a statistically significant reduction relative to the control after exposure to 142 and 280 µg/L. Growth, as measured by wet weight, exhibited a significant reduction after 84 days of exposure to 280 µg/L.

 

F1 generation hatchability, calculated from day 2, was not significantly reduced at any test concentration. F1 generation survival, after 56 days of growth, was not significantly reduced at any test concentration. F1 generation growth, as measured by standard length at 56 days post-hatch, showed a statistically significant reduction after exposure to 142 and 280 µg/L. Growth, as measured by blotted wet weight at 56-day post-hatch, exhibited a significant reduction after exposure to 280 µg/L.

Reference 3

Endpoint:

fish early-life stage toxicity

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

other: US EPA. 1986. Hazard Evaluation Division, Standard Evaluation Procedure, Fish Early Life-Stage Test. Office of Pesticides Programs, Washington, DC 20460

GLP compliance:

yes

Specific details on test material used for the study:

DOX-X1179-394
Purity: 98.35%

Analytical monitoring:

yes

Vehicle:

yes

Remarks:

water

Test organisms (species):

Pimephales promelas

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

35 d

Hardness:

160-172 mg/L (as CaCO3)

Test temperature:

24.6-25.2 °C

pH:

7.94-8.14

Dissolved oxygen:

7.8-8.9 mg/L

Conductivity:

393-430 µS

Nominal and measured concentrations:

Nominal: 0, 19, 38, 75, 150, 300 µg/L
Measured: 0, 18.0, 39.3, 73.0, 145, 261 µg/L

Reference substance (positive control):

no

Key result

Duration:

35 d

Dose descriptor:

other: MATC

Effect conc.:

103 µg/L

Key result

Duration:

35 d

Dose descriptor:

NOEC

Effect conc.:

73 µg/L

Key result

Duration:

35 d

Dose descriptor:

LOEC

Effect conc.:

145 µg/L

Details on results:

Egg hatchability and fry survival were not significantly reduced at any test concentration. Fry growth, as measured by standard length, showed a statistically significant reduction after 35 days exposure to measured concentrations of 145 and 261 µg/L. Fry growth, measured by wet weight, exhibited a significant reduction after 35 days exposure to 145 and 261 µg/L. The NOEC was 73 µg/L; the LOEC was 145 µg/L; and the MATC (defined as the geometric mean of the NOEC and LOEC) was 103 µg/L.

Validity criteria fulfilled:

yes

Conclusions:

35d MATC: 103 µg/L
35d NOEC: 73 µg/L
35d LOEC: 145 µg/L

Executive summary:

A flow-through early life-stage toxicity study with the fathead minnow was conducted to determine the estimated maximum acceptable toxicant concentration (MATC) and to provide preliminary information for a full life-cycle toxicity study. Newly fertilized eggs were used for study initiation with exposure continuing for 35 days. Nominal concentrations were 0, 19, 38, 75, 150, 300 µg/L. The test procedure was conducted according to the draft guidance by US EPA. 1986. Hazard Evaluation Division, Standard Evaluation Procedure, Fish Early Life-Stage Test. Office of Pesticides Programs, Washington, DC 20460.

Egg hatchability and fry survival were not significantly reduced at any test concentration. Fry growth, as measured by standard length, showed a statistically significant reduction after 35 days exposure to measured concentrations of 145 and 261 µg/L. Fry growth, measured by wet weight, exhibited a significant reduction after 35 days exposure to 145 and 261 µg/L. The NOEC was 73 µg/L; the LOEC was 145 µg/L; and the MATC (defined as the geometric mean of the NOEC and LOEC) was 103 µg/L.

Description of key information

Duration/Value Type	Species	Value	Guideline	Reliability
35 -day NOEC	fathead minnow	0.073 mg/L	US EPA. 1986. Hazard Evaluation Division, Standard Evaluation Procedure, Fish Early Life-Stage Test. Office of Pesticides Programs, Washington, DC 20460 K2	2
193 -day NOEC	fathead minnow	0.076 mg/L	EPA OPP 72 -5	1
36- day NOEC	sheepshead minnow	0.26 mg/L	EPA OPP 72 -4	1

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

0.073 mg/L

Marine water fish

Marine water fish

Effect concentration:

0.26 mg/L

Additional information

Chronic fish toxicity tests were conducted in one freshwater species and one marine species. The chronic NOEC value in a 35-day early life stage test in fathead minnows was 0.073 mg/L. In a life cycle study in fathead minnows, the 193-day NOEC was 0.076 mg/L. The saltwater species, sheepshead minnow, had a NOEC of 0.26 mg/L in a 36-day early life stage test.  The fathead minnow was the most sensitive species with a NOEC value of <0.1 mg/L.