Methomyl

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

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:

OECD Guideline 207 (Earthworm, Acute Toxicity Tests)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EU Commission Directive 87/302/EEC (1988)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Methomyl technical
DPX-X1179-512
Purity: 98.6%

Analytical monitoring:

no

Vehicle:

yes

Remarks:

deionised water

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

no

Total exposure duration:

14 d

Test temperature:

20 °C ± 2 °C

Nominal and measured concentrations:

Nominal: 0, 6.25, 12.5, 25, 50, 100 and 200 mg/kg

Reference substance (positive control):

yes

Remarks:

2-chloroacetamide

Key result

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

23 mg/kg soil dw

Nominal / measured:

nominal

Basis for effect:

mortality

Key result

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

6.25 mg/kg soil dw

Nominal / measured:

nominal

Basis for effect:

mortality

Key result

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

6.25 mg/kg soil dw

Nominal / measured:

nominal

Basis for effect:

other: body weight

Key result

Duration:

14 d

Dose descriptor:

LOEC

Effect conc.:

12.5 mg/kg soil dw

Nominal / measured:

nominal

Basis for effect:

mortality

Key result

Duration:

14 d

Dose descriptor:

LOEC

Effect conc.:

12.5 mg/kg soil dw

Nominal / measured:

nominal

Basis for effect:

other: body weight

Details on results:

At all of the tested concentrations of the test substance all earthworms were stiff and inflexible showing little reaction after a mechanical stimulus after 7 and 14 days of exposure. The degree of the observed sublethal effects were the same for all tested concentrations and for both assessment dates (no increase or decrease).

Results with reference substance (positive control):

The LC50 for the toxic reference standard was between 10 and 18 mg/kg dry artificial soil; this is within accepted limits (according to experience between 10 and 56 mg/kg dry weight) and confirms the validity of this test.

Validity criteria fulfilled:

yes

Conclusions:

14-d LC50 = 23 mg/kg dry soil
14-d NOEC = 6.25 mg/kg dry soil (for mortality)
14-d NOEC = 6.25 mg/kg dry soil (for weight loss)
14-d LOEC = 12.5 mg/kg dry soil (for mortality)
14-d LOEC = 12.5 mg/kg dry soil (for weight loss)

Executive summary:

The acute toxicity ofthe test material to earthworms, Eisenia foetida Michaelsen, was estimated in a 14-day soil exposure laboratory study conducted according to OECD Guideline 207 (1984) and EU Commission Directive 87/302/EEC (1988). Four replicates of ten clitellated adult earthworms each were exposed to nominal concentrations of 0, 6.25, 12.5, 25, 50, 100 and 200 mg/kg dry artificial soil (ppm in soil). Controls were replicated four times, with ten earthworms in each replicate. The toxic standard, 2-chloroacetamide, was tested at 0, 10, 18, 32, 56, 100 mg/kg dry artificial soil. Earthworms were assessed for mortality and behavioral effects after 7 and 14 days of exposure and earthworm body weights were assessed at day 0 and day 14.

 

The LC50 was calculated to be 23 mg/kg dry soil with a lower 95 % confidence limit of 20 and an upper confidence limit of 27 mg/kg dry weight. The NOEC for mortality and weight loss was determined to be 6.25 mg/kg dry soil, the LOEC for mortality and weight loss was determined to be 12.5 mg/kg dry soil. The lowest treatment level causing 100 % mortality was recorded at concentration of 100 mg/kg dry weight soil. Following sub-lethal behavioral effects were observed after 7 and 14 days of exposure. At all of the tested concentrations of the test substance all earthworms were stiff and inflexible showing little reaction after a mechanical stimulus. The degree of the observed sub-lethal effects were the same for all tested concentrations of the test substance and for both assessment dates (no increase or decrease). The LC50 for the toxic reference standard was between 10 and 18 mg/kg dry artificial soil; this is within accepted limits (according to experience between 10 and 56 mg/kg dry weight) and confirms the validity of this test.

Reference 2

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

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:

OECD Guideline 207 (Earthworm, Acute Toxicity Tests)

Deviations:

no

Qualifier:

according to guideline

Guideline:

ISO 11268-1 (Effects of Pollutants on Earthworms. 1. Determination of Acute Toxicity Using Artificial Soil Substrate)

Version / remarks:

draft (1983)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Recommendations of the Ad Hoc Working Group of the German Federal Biological Institute (1984)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Methomyl technical
DPX-X1179-512
Purity: 98.6%

Analytical monitoring:

no

Vehicle:

yes

Remarks:

deionized water

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

no

Total exposure duration:

14 d

Test temperature:

20±2 °C

pH:

6.0±0.5

Nominal and measured concentrations:

Nominal: 0, 0.01, 0.1, 1.3, 6.25, 12.5, 25, 50, 100, and 200 mg/kg

Reference substance (positive control):

yes

Remarks:

2-chloroacetamide

Key result

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

19 mg/kg soil dw

Nominal / measured:

nominal

Basis for effect:

mortality

Key result

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

3 mg/kg soil dw

Nominal / measured:

nominal

Basis for effect:

mortality

Key result

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

3 mg/kg soil dw

Nominal / measured:

nominal

Basis for effect:

other: weight loss

Key result

Duration:

14 d

Dose descriptor:

LOEC

Effect conc.:

6.25 mg/kg soil dw

Nominal / measured:

nominal

Basis for effect:

mortality

Key result

Duration:

14 d

Dose descriptor:

LOEC

Effect conc.:

6.25 mg/kg soil dw

Nominal / measured:

nominal

Basis for effect:

other: weight loss

Details on results:

At the concentration of 1 mg/kg dw, the first sublethal effects were recorded during the study. These effects were significant at concentrations ≥ 6.25 mg/kg dw.

Results with reference substance (positive control):

LC50 was between 18 and 32 mg/kg DW; this is within accepted limits and confirms the validity of the test

Validity criteria fulfilled:

yes

Conclusions:

14-d LC50 = 19 mg/kg dry soil
14-d NOEC = 3 mg/kg dry soil (for mortality)
14-d NOEC = 3 mg/kg dry soil (for weight loss)
14-d LOEC = 6.25 mg/kg dry soil (for mortality)
14-d LOEC = 6.25 mg/kg dry soil (for weight loss)

Executive summary:

The acute toxicity of the test material to earthworms, Eisenia foetida Michaelsen, was estimated in a 14-day soil exposure laboratory study conducted according to OECD Guideline 207, ISO 11268-1 (Effects of Pollutants on Earthworms. 1. Determination of Acute Toxicity Using Artificial Soil Substrate) and Recommendations of the Ad Hoc Working Group of the German Federal Biological Institute (1984). Controls were replicated four times, with 10 earthworms in each replicate. Nominal concentrations of 0, 0.01, 0.1, 1.3, 6.25, 12.5, 25, 50, 100, and 200 mg/kg dry artificial soil (ppm in soil) were tested. The toxic standard, 2-chloroacetamide, was tested at 0, 10, 18, 32, 56, 100 mg/kg dry artificial soil. Earthworms were assessed for mortality and behavioral effects after 7 and 14 days of exposure and earthworm body weights were assessed at day 0 and day 14.

 

The LC50 was calculated to be 19 mg/kg dry soil. The NOEC for mortality and weight loss was determined to be 3 mg/kg dry soil, the LOEC for mortality and weight loss was determined to be 6.25 mg/kg dry soil. The lowest treatment level causing 100 % mortality was recorded at concentration of 100 mg/kg dry weight soil. At the concentration of 1 mg/kg dw, the first sub-lethal effects were recorded during the study. These effects were significant at concentrations ≥ 6.25 mg/kg dw. The LC50 for the toxic reference standard was between 10 and 18 mg/kg dry artificial soil; this is within accepted limits (according to experience between 10 and 56 mg/kg dry weight) and confirms the validity of this test.

Description of key information

Duration/Value Type	Species	Value	Guideline	Reliability
14-d LC50	Eisenia foetida Michaelsen	23 mg/kg dry soil	OECD 207, EU Commission Directive 87/302/EEC (1988)	1
14-d NOEC	Eisenia foetida Michaelsen	6.25 mg/kg dry soil	OECD 207, EU Commission Directive 87/302/EEC (1988)	1
14-d LC50	Eisenia foetida Michaelsen	19 mg/kg dry soil	OECD 207, ISO 11268-1	1
14-d NOEC	Eisenia foetidaMichaelsen	3 mg/kg dry soil	OECD 207, ISO 11268-1	1

Key value for chemical safety assessment

Short-term EC50 or LC50 for soil macroorganisms:

19 mg/kg soil dw

Long-term EC10, LC10 or NOEC for soil macroorganisms:

3 mg/kg soil dw