Desmedipham

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Endpoint:

toxicity to soil macroorganisms except arthropods: long-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010-04-30 to 2010-12-07

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

April 13, 2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

ISO 11268-2 (Effects of Pollutants on Earthworms. 2. Determination of Effects on Reproduction)

Version / remarks:

July 1998

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

The test material is a white powder.

Analytical monitoring:

no

Details on preparation and application of test substrate:

- Method of mixing into soil: The test item was mixed with quartz sand as homogeneously as possible. The application mixture of the highest test concentration was further diluted with quartz sand to obtain the desired test concentrations. Uniform amounts of the application mixtures were used for all replicates of the test concentrations. They were thoroughly mixed into the artificial soil of each replicate by using a laboratory mixer, in the order lowest test concentration to highest test concentration.
- Controls: 8 replicates of 10 earthworms (8 x 10)

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Details on test organisms:

TEST ORGANISM
- Common name: Eisenia fetida
- Age at test initiation: approximately 6 months old
- Weight at test initiation: 0.25 g to 0.45 g per worm

ACCLIMATION
- Acclimation period: 7 days
- Acclimation conditions: Seven days prior to the start of exposure, the test organisms were acclimated to the artificial soil and test temperature.

Study type:

laboratory study

Substrate type:

artificial soil

Remarks:

500 g artificial soil (dry weight)

Limit test:

no

Total exposure duration:

8 wk

Remarks:

The study consisted of 2 parts. Adult earthworms were exposed to the a.s. for a period of 4 weeks (first part). Juvenile earthworms remained in the test vessels for additional 4 weeks (second part).

Post exposure observation period:

Mortality and Adverse Effects: after 4 weeks of exposure, living adult earthworms were counted and checked for any abnormal behaviour or other adverse effects (e.g. lack of movement, rigidity etc.). Those earthworms, which did not move after gentle mechanical stimulus, were considered to be dead. Also missing earthworms (compared to the number of initially placed test organisms) were considered to have died, since dead earthworms completely decompose in the soil in short time and hence cannot always be found.
Growth: at the beginning (prior to exposure) and at the end of the 4 weeks of exposure, the adult test organisms of each vessel were weighed (at the start each individually, at the end together of each test vessel). Changes in body weight values of the surviving test organisms of the treatment groups during the test period were compared to the values of the control group.
Reproduction: at the end of the test, after 8 weeks of exposure, the number of surviving juveniles per test vessel was determined. The test vessels were placed in a water bath at 50 – 60°C. By this treatment, alive juvenile earthworms rose to the soil surface. The emerging earthworms were removed and counted. Afterwards, the content of each test vessel was checked additionally by carefully stirring up the artificial soil with the help of tweezers. The reproduction of the surviving test organisms per test vessel at the end of the study was compared to the control values.

Test temperature:

20°C ± 2

pH:

Test start: 6.09; test end: 6.77 - 6.89

Moisture:

29.8 g water / 100 g dry weight artificial soil (nominal 22.96% soil moisture),

Details on test conditions:

TEST SYSTEM
- Test container (material, size): Non-re-usable plastic boxes (length x width x height ca. 16.5 cm x 12 cm x 6 cm, area approximately 200 cm2 )
- Amount of soil or substrate: 500 g artificial soil (dry weight) per test vessel
- No. of organisms per container (treatment): 10 earthworms
- No. of replicates per treatment group: 4 replicates
- No. of replicates per control: 8 replicates

SOURCE AND PROPERTIES OF SUBSTRATE
- Composition (if artificial substrate): Sphagnum peat (shredded): 5%, Kaolinite clay: 20% (content of Kaolinite (Al2 Si2 O5 (OH)4) = 56.0%), Industrial quartz sand (Sort: F 36) (Particle size: 0.20 mm – 0.05 mm = 91.5%): 73.82%, Calcium carbonate (CaCO3) (for the adjustment to pH 6.0 ± 0.5): 0.18%, Food (dried ground cow manure): 1%.
- Maximum water holding capacity (in % dry weight): 58%

OTHER TEST CONDITIONS
- Photoperiod: 16 h light to 8 h darkness photoperiod
- Light intensity: 400 and 800 Lux

Nominal and measured concentrations:

Nominal concentration: 8, 16, 32, 64 and 128 mg a.s./kg dw artificial soil.

Reference substance (positive control):

yes

Remarks:

Carbendazim

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 128 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 128 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

EFFECTS OF TREATMENTS ON SURVIVAL OF ADULTS
A mortality rate of 1.25% of adult earthworms was observed after 28 days of exposure at the control group. A mortality rate of 2.5% was observed at the test concentrations of 16, 32 and 64 mg a.s./kg dry weight artificial soil. This mortality was not considered to be treatment related. No mortality of adult earthworms was observed at the test concentrations of 8 and 128 mg a.s./kg dry weight artificial soil after 28 days of exposure (see Table 1 and 2).

EFFECTS OF TREATMENTS ON BIOMASS OF ADULTS
The mean body wet weight of the ten earthworms in each replicate from the control and from all treatment groups at test start, and the mean weights of the surviving animals after the exposure period of 28 days are listed in Table 2. The individual wet weights of all test organisms at test start are given in the APPENDIX I. The mean body weight of the adult earthworms in the control group had increased during the 4 weeks of exposure. The mean body weight was 0.45 g per worm (+ 43.9% of the mean initial weight; see Table 2). The mean changes in body weight of the test concentrations of 8, 16, 32, 64 and 128 mg test item / kg dry weight soil were + 48.3%, + 32.7%, + 38.1%, + 29.3% and + 34.8%, respectively. No statistically significant different values for the growth relative to the control were observed at any test concentration of the test item in this study (result of a Williams Multiple Sequential t-test, two-sided, a = 0.05).

EFFECTS OF TREATMENTS ON THE REPRODUCTION
Table 4 shows the total number of living offspring, produced by all adults within 28 days of continuous exposure expressed per test vessel and per surviving adult (reproduction rate). In the control group, on average 192.1 juvenile earthworms per test vessel were found (corresponding to a mean reproduction rate of 19.5 juveniles per surviving adult). At the a.s. treatment groups exposed to Desmedipham tech. up to and including the highest test concentration of 128 mg a.s./kg dry weight artificial soil, the mean reproduction rate was in the range of 95.8% to 103.6% of the control value.

Results with reference substance (positive control):

The results of the reference test item indicated that the test system was sensitive to the reference test item. No mortality of the adult earthworms was observed 28 days after application (just one worm died in one of the control vessels). No statistically significant different values for the biomass relative to the control were observed at the lowest test concentration of 1.25 mg a.s./kg dry weight artificial soil. The change of body weight of the adult earthworms of the test concentrations of 2.5 and 5.0 mg a.s./kg dry weight soil was statistically significant reduced in comparison to the control (results of a Williams multiple sequential t-test, two-sided, a = 0.05). No statistically significant different values for the number of juveniles per test vessel relative to the control were observed at the lowest test concentration of 1.25 mg a.s./kg dry weight artificial soil. The number of juveniles per test vessel of the test concentrations of 2.5 and 5.0 mg a.s./kg dry weight soil were statistically significant reduced to the control (results of a multiple sequential U-test after Bonferoni-Holm, one-sided smaller, a = 0.05.

See "Attachments" in "Overall remarks, attachments" for the tables and appendix;

Validity criteria fulfilled:

yes

Conclusions:

The study fulfilled the validity criteria for control mortality (<10%), for the mean number of offsprings per test vessel (= 30) and for the coefficient of variance of reproduction (=30%). Also, the physico-chemical parameters measured at the start and at the end of the tests met the guideline requirements. The toxic standard showed statistically significant reduction in the number of juveniles at test concentration of 5 mg a.s./kg dw soil. The study is considered valid. The NOEC value is = 128 mg a.s./kg dry weight soil.

Executive summary:

This study was conducted in order to determine the toxicity of desmedipham technical to the earthworm Eisenia fetida in artificial soil with 5% peat, and its effects on survival, growth and reproduction. The test was conducted at the following nominal concentrations of the test substance: 0 (control),  8, 16, 32, 64 and 128 mg a.s./kg dw artificial soil. Mortality was observed after 28 days of exposure at the control group (1.25%) and at the test concentrations of 16, 32 and 64 mg a.s./kg dry weight artificial soil (2.5% at each named concentration) in this study. This mortality was not considered to be treatment related. No mortality of adult earthworms was observed at the test concentrations of 8 and 128 mg a.s./kg dry weight artificial soil after 28 days of exposure. No statistically significant different values for the growth relative to the control were observed. No statistically significant different values for the number of juveniles per test vessel relative to the control were observed. Overall, based on the biological and statistical significance of the effects observed on growth and reproduction, it is concluded, that the NOEC for this study is ≥128 mg a.s./kg dry weight soil.

Description of key information

The purpose of this study was to determine the sublethal effects of Desmedipham on reproduction, mortality, and growth of the earthworm Eisenia fetida in a laboratory test. Mortality and biomass change were determined after 4 weeks, and reproduction was determined after 8 weeks. The NOEC (reproduction) was determined to be ≥128 mg/kg soil dw.

In the table below all available studies are listed. For some studies only the results are presented since they are not considered relevant due to the reasons given under “Assessment”. All available studies have been evaluated within the scope of Plant Protection Regulation in the respective Draft Renewal Assessment Report (DAR) under Regulation (EC) 1107/2009.

Test species	Result	Assessment	Reference
Eisenia fetida	NOEC (56-d) ≥128 mg/kg dws	Key study	Leicher (2010)

Key value for chemical safety assessment

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

128 mg/kg soil dw