Pirimiphos-methyl

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

May 1993 to Jul 1993

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 207 (Earthworm, Acute Toxicity Tests)

Version / remarks:

April 1984

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

other: C(L1)4 Toxicity for Earthworms Artificial Soil Test, Revision 6

Version / remarks:

prepared for Annex V of EEC Directive 79/83

Deviations:

not specified

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

yes

Remarks:

acetone

Details on preparation and application of test substrate:

PREPARATION OF TEST SOLUTIONS
The 10 mg ai/kg treatment was included to increase the chances that a NOEL would be determined in the definitive test. The doses were prepared in 50 mL of acetone tor application to 2.5 kg (dry weight equivalents) of artificial soil. The control comprised 50 mL of acetone.

APPLICATION AND INCORPORATION OF TEST SOLUTIONS IN ARTIFICIAL SOIL
The weighed artificial soil was spread out on a 46 cm x 57 cm piece of 'Benchkote' and placed in a fume cupboard. The prepared solution was sprayed onto the surface through a fan jet. The soil was left at room temperature until the acetone had evaporated from the soil surface (1-2 hours), and then poured into a food mixer bowl. The soil was mixed for two minutes by a heavy duty food mixer to evenly incorporate the test substance into the soil. Deionised water was then added to bring the moisture content of the soil up to 50% and mixing continued for a further two minutes. Soil aliquots (750 g fresh weight) were weighed out into 1 L glass beakers. For the initial test, E. foetida were exposed in two aliquots (replicates) of treated soil and for the definitive test, four aliquots of soil per treatment.

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Details on test organisms:

TEST ORGANISM
- Common name: Earthworm
- Cultivation: Cultured in bulb fibre compost at the test facility
- Arrived date: 9 May 1990 (cultured in a controlled environment room since arrival)
- Weight at test initiation: 0.42 ± 0.04 g

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

no

Total exposure duration:

14 d

Test temperature:

20 ± 2 °C

pH:

6.0 ± 0.3

Moisture:

50 ± 8%

Details on test conditions:

TEST SYSTEM
- Test container: 1 L glass beaker
- Amount of soil or substrate: 750 g fresh weight
- No. of organisms per container: 10
- No. of replicates per treatment group: 4
- No. of replicates per vehicle control: 4
- No. of replicates per reference substance concentration: 4

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
The test artificial soil was a mixture of the following ingredients in oven (approximately 105 °C) dry weight proportions:
- % sand: 70% fine silica sand (Grade 110)
- % peat: 10% peat (Shamrock Moss) organic matter 97.7%
- % clay: 20% kaolinite clay (GTY Powder)
- CaCO3: Calcium carbonate was incorporated into the soil at 5 g/kg. Ingredients, in their natural fresh weight form, were mixed in a rotary cement mixer.

OTHER TEST CONDITIONS
- Photoperiod: Continuously
- Light intensity: 750-1,000 lux (via six sluorescent white tubes)
- Addition to test earthworms: The test earthworms had been preconditioned in untreated artificial soil (50% moisture content) for the previous 24 hours before adding to the test container. The E. foetida were placed on the surtace of the soil between 1 and 2 hours after chemical treatment, and transparent plastic film was placed over the top to prevent them from escaping. Six small holes were made in the transparent plastic film to allow ventilation.
- Moisture contents: Measured at the beginning and end of the tests. Moisture contents were maintained by surtace watering with deionised water.


EFFECT PARAMETERS MEASURED
- Weight: Each batch of ten E. foetida was weighed so that any weight change at the end of the exposure period could be measured. The mean weight and standard deviation of E. foetida used in the test was determined from these weighings.
- Mortality: E. foetida were assessed for mortality and any abnormal behavioural effects after 14 days in the initial test and after 7 and 14 days in the definitive test. The soil was tipped onto a clean surtace and E. foetida were recorded as dead if there was no response to a mechanical stimulus of their front end. Any E. foetida not found after careful searching of the soil were assumed to be dead.

VEHICLE CONTROL PERFORMED: Yes

RANGE FINDING STUDY
- Test concentrations: The test substance has a low solubility in water. The solutions of the test material were, therefore, prepared in acetone by serial dilution and made up to 25 mL tor application to the artificial soil. 25 mL of acetone was used for the preparation of the control soil. The solutions were applied to 1.25 kg (dry weight equivalents) of artificial soil. Soil concentrations were 0, 1, 10, 100 and 1,000 mg ai/kg artificial soil (dry weight).
- Results used to determine the conditions for the definitive study: The result indicated that the LC50 was between 100 and 1,000 mg ai/kg. Thus, the test concentrations for the definitive test were10, 100, 180, 320, 560 and 1,000 mg ai/kg.

Nominal and measured concentrations:

Nominal concentration: 0 (vehicle control), 10, 100, 180, 320, 560 and 1000 mg ai/kg soil dw.

Reference substance (positive control):

yes

Remarks:

2-chloroacetamide

Key result

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

419 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

10 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: mortality and body weight

Details on results:

An overview of the results is provided in Table 1 - Table 3 in 'Any other information on results incl. tables'.
- Mortality: After 14 days exposure, all tested organisms survived in the control, 10 and 100 mg ai/kg soil dw treated groups. There was one earthworm dead in replicate 1 beaker in 180 mg ai/kg soil dw treated group and all other organisms survived. The number of dead worms in the 320 mg ai/kg soil dw treated groups were 2, 7, 1 and 4 in replicate 1, 2, 3 and 4, respectively. The number of dead worms in the 560 mg ai/kg soil dw treated groups were 9, 4, 5 and 10 in replicate 1, 2, 3 and 4, respectively. The number of dead worms in the 1000 mg ai/kg soil dw treated groups were 9, 9,10 and 10 in replicate 1, 2, 3 and 4, respectively.

- Bodyweight: After 14 days exposure, the mean final bodyweight of the control was 4.69 g. The final bodyweight of 10, 100, 180, 320, 560 and 1000 mg ai/kg soil dw were 4.90, 2.75, 2.89, 2.06, 2.25 and 2.20g respectively.
There were no deaths, effects on external condition or behaviour or significant bodyweight changes (P = 5%) at 10 mg ai/kg soil dw. Hence, NOEL was at least 10 mg ai/kg soil dw. There were high bodyweight losses in all groups of surviving earthworms at and above the 100 mg ai/kg soil concentration. The LC50 was determined to be 419 mg ai/kg soil dw.

Results with reference substance (positive control):

After 14 days exposure, all tested organisms survived in the control, 18 and 32 mg chloroacetamide/kg soil dw treated groups. The number of dead worms in the 56 mg chloroacetamide/kg soil dw treated groups were 9, 9, 9 and 10 in replicate 1, 2, 3 and 4, respectively.
After 14 days exposure, the mean final bodyweight of the control was 4.69 g. The final bodyweight of control, 18 and 32 mg chloroacetamide/kg soil dw were 4.13, 4.87 and 4.78 g respectively. For the 56 mg/kg soil dw treated group, only one worm survived which was deemed to be insufficient to calculate the bodyweight change of ten worms. Based on the findings, the LC50 value for chloroacetamide, tested as a toxic standard, was 43 mg/kg soil dw.

Reported statistics and error estimates:

See Statistical analysis in 'Any other information on materials and methods incl. tables'.

Table 1. Number of dead and weight of live E. foetida after 14 days exposure to the test substance in artificial soil.

Concentration in soil (mg ai/kg)	Replicate	Numbers dead out of 10		Weight of 10 organisms
		7 days	14 days	Day 0	Day 14	% change
Control	1	0	0	4.40	4.83	+9.8
	2	0	0	3.84	4.7	+22.4
	3	0	0	3.62	4.45	+22.9
	4	0	0	4.22	4.78	+13.3
10	1	0	0	4.62	5.08	+10
	2	0	0	4.59	5.22	+13.7
	3	0	0	4.05	4.53	+11.9
	4	0	0	4.31	4.75	+10.2
100	1	0	0	4.34	3.05	-29.7
	2	0	0	3.92	2.34	-40.3
	3	0	0	4.25	2.54	-40.2
	4	0	0	3.94	3.06	-22.3
180	1	0	1	4.44	3.07^a	-30.9
	2	0	0	4.45	2.96	-33.5
	3	0	0	4.95	3.09	-37.6
	4	0	0	4.13	2.42	-41.4
320	1	2	2	3.97	2.38	-10.1
	2	4	7	3.88	1.80^a	-53.6
	3	1	1	4.14	2.19^a	-47.1
	4	3	4	3.53	1.88^a	-46.7
560	1	5	9	4.16	1.6^a	-61.5
	2	3	4	3.95	2.07^a	-47.6
	3	3	5	4.51	3.08^a	-31.7
	4	8	10	3.97	-	-
1000	1	6	9	4.58	2.50^a	-45.4
	2	5	9	4.78	1.90^a	-60.0
	3	5	10	3.58	-	-
	4	7	10	4.10	-	-

a.Where mortality occurred, the final weight and the percentage weight change were adjusted for the dead earthworms using the following calculation:

Final weight tor 10 worms (g) = Weight of remaining worms (g) x (No. Exposed (10)/No. surviving)

Table 2. Number of dead and weight of liv eE. foetida after 14 days exposure to 2-chloroacetamlde in artificial soil.

Chloroacetamide Goncentration in Soil (mg kg-1)	Replicate	Numbers dead out of 10		Weight of 10 E. foetida (g)
		7 days	14 days	Start Day 0	Finish Day 14	% Change
Control	1	0	0	4.16	3.92	-5.8
	2	0^a	0^a	4.86	4.51	-7.2
	3	0	0	4.22	4.06	-3.8
	4	0	0	4.06	4.02	-1.0
18	1	0	0	4.69	5.16	+10.0
	2	0	0	4.38	4.82	+10.0
	3	0	0	4.37	4.77	+9.2
	4	0	0	4.19	4.73	+12.9
32	1	0	0^c	4.22	4.22	0
	2	0	0	4.49	4.72	+5.1
	3	0	0	4.82	5.26	+9.1
	4	0	0	4.69	4.93	+5.1
56	1	9	9	4.52	-^d	-
	2	9^b	9^b	4.27	-^d	-
	3	9	9	3.84	-^d	-
	4	10	10	4.33	-	-

a. One affected worm: body lesion, possible mechanical damage.

b. One affected worm: uncoordinated and had lost rear segments.

c. One affected worm: .had lost rear segments.

d. Only one worm survived which was deemed to be insufficient to calculate the bodyweight change of ten worms, and therefore a percentage bodyweight change was not recorded.

Table 3. Treatment means of E. foetida bodywelghts after 14 days exposure to the test substance in artificial soil.

Treatment	Mean Adjusted Final Bodyweights and (Standard Errors) for Groups of 10 Earthworms (g)
Control	4.85 (0.13)
10 mg ai/kg	4.80 (0.12)
100 mg ai/kg	2.84 (0.12)^a
180 mg ai/kg	2.72 (0.13)^a

a. Significantly different from the control (P = 5%)

 

 

Validity criteria fulfilled:

yes

Conclusions:

Based on the findings, the LC50 of the test substance was determined to be 419 ai/kg soil dry weight, and the NOEC was determined to be 10 mg a.i./kg soil dry weight.

Executive summary:

A laboratory study was conducted to determine the acute toxicity of the test substance to earthworms (Eisenia foetida). The study was conducted in accordance with OECD TG 207 and in compliance with GLP criteria. The study was performed with six test concentrations (10, 100, 180, 320, 560 and 1000 mg a.i./kg soil dw) and a solvent control group (acetone). Chloroacetamide was used as toxic standard (nominal concentrations were control, 18, 32 and 56 mg/kg soil dw). Four replicates were used per test concentration, each replicate containing ten organisms. The test substrate was an artificial soil prepared with 70% sand, 20% kaolin and 10% peat. The test was conducted under continuous 750 – 1000 lux light intensity and at a temperature of 20 ± 2 °C. Mortality and body weight was recorded throughout the study.

 

After 14 days, all organisms survived in the control, 10 and 100 mg a.i./kg soil dw treatment groups. The number of dead worms in the 320 mg ai/kg soil dw treated groups were 2, 7, 1 and 4 in replicate 1, 2, 3 and 4, respectively. The number of dead worms in the 560 mg ai/kg soil dw treated groups were 9, 4, 5 and 10 in replicate 1, 2, 3 and 4, respectively. The number of dead worms in the 1000 mg ai/kg treated groups were 9, 9,10 and 10 in replicate 1, 2, 3 and 4, respectively. The mean final bodyweight of the control was 4.69 g. The final bodyweight of 10, 100, 180, 320, 560 and 1000 mg ai/kg soil were 4.90, 2.75, 2.89, 2.06, 2.25 and 2.20g respectively. Based on the findings, the LC50 of the test substance was determined to be 419 mg ai/kg soil dry weight, and the NOEC was determined to be 10 mg a.i./kg soil dry weight.

Description of key information

14-d LC50 = 419 mg a.i./kg soil dw, Eisenia foetida, OECD TG 207, Coulson et al., 1993

Key value for chemical safety assessment

Short-term EC50 or LC50 for soil macroorganisms:

419 mg/kg soil dw

Additional information

A laboratory study was conducted to determine the acute toxicity of the test substance to earthworms (Eisenia foetida). The study was conducted in accordance with OECD TG 207 and in compliance with GLP criteria. The study was performed with six test concentrations (10, 100, 180, 320, 560 and 1000 mg a.i./kg soil dw) and a solvent control group (acetone). Chloroacetamide was used as toxic standard (nominal concentrations were control, 18, 32 and 56 mg/kg soil dw). Four replicates were used per test concentration, each replicate containing ten organisms. The test substrate was an artificial soil prepared with 70% sand, 20% kaolin and 10% peat. The test was conducted under continuous 750 – 1000 lux light intensity and at a temperature of 20 ± 2 °C. Mortality and body weight was recorded throughout the study.

 

After 14 days, all organisms survived in the control, 10 and 100 mg a.i./kg soil dw treatment groups. The number of dead worms in the 320 mg ai/kg soil dw treated groups were 2, 7, 1 and 4 in replicate 1, 2, 3 and 4, respectively. The number of dead worms in the 560 mg ai/kg soil dw treated groups were 9, 4, 5 and 10 in replicate 1, 2, 3 and 4, respectively. The number of dead worms in the 1000 mg ai/kg treated groups were 9, 9,10 and 10 in replicate 1, 2, 3 and 4, respectively. The mean final bodyweight of the control was 4.69 g. The final bodyweight of 10, 100, 180, 320, 560 and 1000 mg ai/kg soil were 4.90, 2.75, 2.89, 2.06, 2.25 and 2.20g respectively. Based on the findings, the LC50 of the test substance was determined to be 419 mg ai/kg soil dry weight, and the NOEC was determined to be 10 mg a.i./kg soil dry weight.