Avermectin A1a, 25-cyclohexyl-5-O-demethyl-25-de(1-methylpropyl)-

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to soil macroorganisms except arthropods: long-term

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

From 14 Dec 2001 to 25 Jan 2002

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study run to a method comparable with current guidelines and to GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 220 (Enchytraeid Reproduction Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

not specified

Vehicle:

yes

Details on preparation and application of test substrate:

The test concentrations were formulated by the addition of 2.0 mL of the respective stock solution to 2.5 g of quartz sand. The acetone was then allowed to evaporate under a fume hood for approximately 1.5 hours, and the sand was added to test vessels containing 22 g hydrated artificial soil and mixed thoroughly.
The control was prepared by adding 2.0 mL acetone to 2.5 g quartz sand and treating as described above.

Test organisms (species):

Enchytraeus albidus

Animal group:

annelids

Details on test organisms:

TEST ORGANISM
- Common name: Enchytraeid Worm
- Source: purchased from a commercial supplier (Dan Ogrizek, Wadsworth, Ohio)
- Age at test initiation (mean and range, SD):
- Weight at test initiation (mean and range, SD):

ACCLIMATION
- Acclimation period: 2 days
- Acclimation conditions (same as test or not): Two days prior to the start of the definitive toxicity test, the worms were transferred to artificial soil (industrial sand, kaolin clay, and freely ground sphagnum peat in a 70:20:10 ratio by weight) and maintained in the dark at 20±2℃. The culture was supplied with autoclaved, finely ground rolled oats (Quaker 100% Rolled fiats) as a food source placed on the soil surface and mixed into the soil twice each week during acclimation.
- Health during acclimation (any mortality observed): no mortality was observed.

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

no

Total exposure duration:

42 d

Test temperature:

18.2-19.8℃

pH:

5.9-6.4

Moisture:

19-21%

Details on test conditions:

TEST SYSTEM
- Test container (material, size): 250 mL glass beakers
- Amount of soil or substrate: 24.5 g (20 g dry weight equivalent) of dosed, artificial soil (soil depth was approximately 0.9 cm)
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 4
- No. of replicates per positive control: 2
- No. of replicates per vehicle control: 8

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Composition (if artificial substrate): Soil was formulated by combining industrial sand (Amestone Natural Playsand, American Stone-Mix, Inc.), kaolin clay (Dry Branch Kaolin Company), and finely ground sphagnum peat (Lambert) in a 70:20:10 ratio by weight.
- Maximum water holding capacity (in % dry weigth): 33%
- Pretreatment of soil: One day before the start of the definitive toxicity test, the moisture content of the artificial soil was adjusted to 40 to 60% of the water holding capacity by the addition of deionized water.

OTHER TEST CONDITIONS
- Photoperiod: 16 hour light and 8 hour dark
- Light intensity: approximately 660 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): After three weeks, the number of surviving adult worms and the occurrence of sublethal effects (inability to burrow, immobility, open wounds, color change, etc.) was determined. At the end of the second three week period, juveniles were sieved through Nitex screen and counted.
Soil temperature was measured and recorded weekly in each test vessel and the temperature in a representative vessel was recorded continuously during the test. The moisture content and pH of the control substrate and a sample of substrate from each test concentration (collected from the additional test vessels) was determined at the beginning and end of the test.

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: Nominal concentrations: 0.089, 0.89, 8.9, 89, and 890 mg a.i./kg (dry weight)
- Results used to determine the conditions for the definitive study: After 21 days of exposure (10 worms/concentration, single replicate), there was 90% survival of adult worms in the control, 100% survival at 0.089, 0.89, and 8.9 mg a.i./kg, 90% survival at 89 mg a.i./kg, and 30% survival at 890 mg a.i./kg. The total number of juveniles produced, counted after 42 days of exposure, was as follows: control =60, 0.089 mg a.i./kg=66, 0.89 mg a.i./kg=59, 8.9 mg a.i./kg=60, 89 mg a.i./kg=11, and 890 mg a.i./kg=6.

Nominal and measured concentrations:

Nominal concentrations: 13, 24, 43, 77, 140, and 250 mg a.i./kg

Reference substance (positive control):

yes

Remarks:

carbendazim

Duration:

42 d

Dose descriptor:

NOEC

Effect conc.:

13 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Details on results:

Survival of adult worms exposed to the six test substance concentrations ranged from 83 to 98% after 21 days of exposure. No sublethal effects were observed during the test. At the conclusion of the definitive test (42 days after test start), juvenile production in the control and at 13, 24, 43, 77, 140, and 250 mg a.i./kg test substance averaged 57, 43, 32, 30, 15, 2, and <1 juveniles, respectively.

Results with reference substance (positive control):

A 42 day soil toxicity test was also conducted with the reference toxicant carbendazim at nominal concentrations of 0.10, 1.0, and 10 mg a.i./kg. After 21 days of exposure, there was 90 to 100% survival of adult worms at all tested concentrations. At the conclusion of the reference toxicant test (42 days after test start), juvenile production at 0.10, 1.0, and 10 mg a.i./kg averaged 27, 18, and 5 juveniles, respectively.

Reported statistics and error estimates:

The no observed effect concentration (NOEC) was determined using fecundity data (the number of juveniles produced). The fecundity data were demonstrated to be normally distributed with a Chi-square test and variances were demonstrated to be homogeneous with a Bartlett's test (α=0.05). The data from the treatments were compared to control data using Bonferroni's test (Galley, et al, 1990). Concentrations that allowed differential mortality or sublethal effects were noted.

Validity criteria fulfilled:

yes

Conclusions:

Exposure of adult enchytraeid worms, Eachytraeus albidus, to the test substance resulted in a no observed effect concentration (NOEC) of 13 mg a.i./kg based on the number of juveniles produced. The three validation criteria specified in the guideline for the control samples were met.

Reference 2

Endpoint:

toxicity to soil macroorganisms except arthropods: long-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 22 Oct to 17 Dec 2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study run to a method comparable with current guidelines and to GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 222 (Earthworm Reproduction Test (Eisenia fetida/Eisenia andrei))

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

not specified

Vehicle:

yes

Details on preparation and application of test substrate:

The test concentrations were formulated by the addition of 1.0 mL of the respective stock solution to 5 g of quartz sand. The acetone was then allowed to evaporate under a fume hood for approximately 2 hours, and the sand was added to test vessels containing 650 g hydrated artificial soil and mixed thoroughly.
The control was prepared by adding 1.0 mL acetone to 5 g quartz sand and treating as described above.

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Details on test organisms:

TEST ORGANISM
- Common name: Earthworm
- Source: purchased from a commercial supplier (B&B Worm Farm, Meeker, Oklahoma)
- Age at test initiation (mean and range, SD): Adult worms used in the test were between two months and 1 year old upon receipt, with individuals differing in age by no more than four weeks.
- Weight at test initiation (mean and range, SD): range from 348 to 664 mg (mean=537 mg)

ACCLIMATION
- Acclimation period: five days
- Acclimation conditions (same as test or not): Five days prior to the start of the definitive toxicity test, the worms were transferred to artificial soil (industrial sand, kaolin clay, and freely ground sphagnum peat in a 70:20:10 ratio by weight) and maintained at 20±2℃. The culture was supplied with horse manure as a food source during this period.
- Health during acclimation (any mortality observed): no mortality was observed.

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

no

Total exposure duration:

56 d

Test temperature:

20±2℃

pH:

5.3-6.1

Moisture:

23-26 %

Details on test conditions:

TEST SYSTEM
- Test container (material, size): 0.5 gallon glass jars
- Amount of soil or substrate: 655 g of hydrated (505 g dry) artificial soil (soil depth was approximately 6 cm)
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 4
- No. of replicates per positve control: 2
- No. of replicates per vehicle control: 8

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Composition (if artificial substrate): Soil was formulated by combining industrial sand (Amestone Natural Playsand, American Stone-Mix, Inc.), kaolin clay (Dry Branch Kaolin Company), and finely ground sphagnum peat (Lambert) in a 70:20:10 ratio by weight.
- Maximum water holding capacity (in % dry weigth): 44%
- Pretreatment of soil: One day before the start of the definitive toxicity test, the moisture content of the artificial soil was adjusted to 40 to 60% of the water holding capacity by the addition of deionized water and the test vessels were covered with plastic to prevent water loss.

OTHER TEST CONDITIONS
- Photoperiod: 16 hour light and 8 hour dark
- Light intensity: approximately 780 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): After four weeks, the number of surviving adult worms and the occurrence of sublethal effects (inability to burrow, immobility, open wounds, color change, etc.) was determined. The time required for burrowing of adult worms at day 0 and after 4 weeks was noted, and the average weight of adult worms was determined. All adult worms were removed after the first 4 week period by sorting through the soil. The test substrates, including any cocoons, were then incubated for an additional four weeks. At the end of the second four week period, the test containers were placed in a water bath adjusted to approximately 40℃ and the temperature was raised to approximately 60℃. After approximately 20 to 30 minutes the juvenile worms, which moved to the surface, were removed and counted.
Soil temperature was measured and recorded weekly in each test vessel and the temperature in one control vessel was recorded continuously during the test. The moisture content and pH of the control substrate and a sample of substrate from each test concentration was determined at the beginning and end of the test.

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: Nominal concentrations: 0.094, 0.94, 10, 100 and 1000 mg a.i./kg (dry weight)
- Results used to determine the conditions for the definitive study: After 28 days of exposure, there was 100% survival of adult worms in the control and at 0.094 mg a. i./kg, 70% survival at 0.94 mg a.i./kg, 90% survival at 10 mg a.i./kg, 60% survival at 100 mg a.i./kg, and 90% survival at 1,000 mg a.i./kg. Average weight change was as follows: control=+13%, 0.094 mg a.i./kg=-7%, 0.94 mg a.i./kg= -16%, 10 mg a.i./kg= +4%, 100 mg a.i./kg=-41%, and 1000 mg a.i./kg= -30%. The total number of juveniles produced, counted after 56 days of exposure, was as follows: control=53, 0.094 mg a.i./kg=56, 0.94 mg a.i./kg=0, 10 mg a.i./kg=32, 100 and 1,000 mg a.i./kg=0.

Nominal and measured concentrations:

Nominal concentrations: 0.50, 0.89, 1.6, 2.9, 5.1, 9.3, and 17 mg a.i./kg

Reference substance (positive control):

yes

Remarks:

carbendazim

Duration:

56 d

Dose descriptor:

NOEC

Effect conc.:

0.89 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Details on results:

Survival of adult worms exposed to the seven test substance concentrations ranged from 93 to 100% after 28 days of exposure. All surviving adult worms exposed to the control, and 0.50, 0.89, 1.6, 2.9, 5.1, and 9.3 mg a.i./kg test substance burrowed into the soil within 15 minutes on days 0 and 28. Adult worms exposed to 17 mg a.i./kg burrowed into the soil within 15 minutes on day 0, and required 25 to >30 minutes to burrow on day 28. No other sublethal effects were observed during the test. Adult worm weight loss averaged 29% in the control and 15 to 36% in the seven test substance concentrations after 28 days. At the conclusion of the definitive test (56 days after test start), juvenile production in the control and at 0.50, 0.89, 1.6, 2.9, 5.1, 9.3, and 17 mg a.i./kg test substance averaged 239, 228, 220, 165, 74, 4, <1, and 1 juveniles, respectively.

Results with reference substance (positive control):

After 28 days of exposure, there was 100% survival of adult worms at all tested concentrations. All surviving adult worms burrowed into the soil within 15 minutes on days 0 and 28. Adult worm weight loss during the reference toxicant test averaged 25 to 35% after 28 days (control weight loss was 35%). At the conclusion of the reference toxicant test (56 days after test start), juvenile production at 0.099, 0.99, and 9.9 mg a.i./kg averaged 209, 161, and 26 juveniles, respectively. The NOEC for worms exposed to carbendazim was 0.099 mg a.i./kg, based on the number of juveniles produced.

Reported statistics and error estimates:

The no observed effect concentration (NOEC) was determined using fecundity data (the number of juveniles produced). The fecundity data were demonstrated to be normally distributed with a Chi-square test and variances were demonstrated to be homogeneous with a Bartlett's test (α=0.05). The data from the treatments were compared to control data using Bonferroni's test (Galley, et al, 1990). Concentrations that allowed greater weight gain (or lesser weight loss) than the control or differential mortality or sublethal effects were noted.

Validity criteria fulfilled:

yes

Conclusions:

Exposure of adult earthworms, Eisenia fetida, to the substance resulted in a no observed effect concentration (NOEC) of 0.89 mg a.i./kg based on the number of juveniles produced.

Reference 3

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From Jul 30 to Sep 10, 2015

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

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch No.: DOA0141202
Purity: 96.6%

Analytical monitoring:

no

Vehicle:

no

Details on preparation and application of test substrate:

The test substance was directly added into the soil. A total amount of 10 g mixture of test substance and quartz sand was prepared firstly and mixed with 550 g dry weight of soil for each test container.

Test organisms (species):

Eisenia fetida

Details on test organisms:

TEST ORGANISM
- Common name: earthworms
- Source: an earthworm nursery of Nanjing city in China
- Age at test initiation (mean and range, SD): 166 days
- Weight at test initiation (mean and range, SD): 359 - 413 mg

ACCLIMATION
- Acclimation period: 24 h
- Acclimation conditions (same as test or not): same
- Health during acclimation (any mortality observed): no

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

yes

Total exposure duration:

14 d

Test temperature:

20.8-21.6℃

pH:

6.37 to 6.58

Moisture:

26 to 35%

Details on test conditions:

TEST SYSTEM
- Test container (material, size): Glass spoutless beakers, 1L
- Amount of soil or substrate: 560 g
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 4
- No. of replicates per control: 4
- No. of replicates per vehicle control: no

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Soil texture (artificial soil): 10% sphagnum peat, 20% kaolin clay, 70% quartz sand.


OTHER TEST CONDITIONS
- Photoperiod: continuous light
- Light intensity: 400 to 800 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
On the 7th and 14th day of exposure, mortality was assessed. The number and type of behavioural and dother pathological abnormalities were determined during each mortality assessment on 7 d and 14 d. pH value and moisture content was determined. The worms average weights were weighed on day 0 and day 14.

VEHICLE CONTROL PERFORMED: no

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 100 ,500 and 1000 mg/kg dry weight of soil
- Results used to determine the conditions for the definitive study: no worms dead.

Nominal and measured concentrations:

1000 mg/kg (dry weight of soil)

Reference substance (positive control):

yes

Remarks:

2-chloracetamide

Key result

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

> 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

No dead worms were observed in treatments and control.
At the beginning of administration, test worms soon disappeared into the test soil medium. During the test, all earthworms remained in the soil.

Validity criteria fulfilled:

yes

Conclusions:

The 7d and 14d LC50 of the test substance to earthworms in artificial soil were both greater than 1000 mg/kg dry weight soil.

Description of key information

Short term:

The 7d and 14d LC50 of the test substance to earthworms in artificial soil were both greater than 1000 mg/kg dry weight soil.

Long term: Two studies are available.

Exposure of adult enchytraeid worms, Eachytraeus albidus, to the test substance resulted in a no observed effect concentration (NOEC) of 13 mg a.i./kg based on the number of juveniles produced.

Exposure of adult earthworms, Eisenia fetida, to the substance resulted in a no observed effect concentration (NOEC) of 0.89 mg a.i./kg based on the number of juveniles produced.

Key value for chemical safety assessment

Short-term EC50 or LC50 for soil macroorganisms:

1 000 mg/kg soil dw

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

0.89 mg/kg soil dw

Additional information

Short term:

The 7d and 14d LC50 of the test substance to earthworms in artificial soil were both greater than 1000 mg/kg dry weight soil in an OECD 207 study.

Long term: Two studies are available.

One was conducted on Enchytraeid worms according to OECD 220 under GLP (Boeri, 2002). Another was conducted on Earthworms according to OECD 222 under GLP (Boeri, 2002).

Exposure of adult enchytraeid worms, Eachytraeus albidus, to the test substance resulted in a no observed effect concentration (NOEC) of 13 mg a.i./kg based on the number of juveniles produced. The three validation criteria specified in the guideline for the control samples were met.

Exposure of adult earthworms, Eisenia fetida, to the substance resulted in a no observed effect concentration (NOEC) of 0.89 mg a.i./kg based on the number of juveniles produced.

The study on Earthworms was selected as key study due to lower NOEC value.