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Toxicity to soil macroorganisms except arthropods

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Endpoint:
toxicity to soil macroorganisms except arthropods: short-term
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2017-11-16 to 2017-12-01
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 207 (Earthworm, Acute Toxicity Tests)
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
Batch No.: 20170214
Purity: >99%
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
other: Eisenia foetida
Details on test organisms:
TEST ORGANISM
- Source: obtained from Chenggong Earthworm Raising Farm in Dongli District, Tianjin.
- Weight at test initiation: At the beginning, the range of body weight was 0.3948g ~ 0.5253g in the control group and 0.3533g ~ 0.5418g in the test concentrations

ACCLIMATION
- Acclimation conditions (same as test or not): Before at least 24 hours of the test, the earthworm was conditioned in an artificial soil under the test condition.
Study type:
laboratory study
Substrate type:
artificial soil
Limit test:
yes
Total exposure duration:
14 d
Test temperature:
19.7°C ~ 20.6°C
pH:
The pH value was 5.91 and 5.86 for the control and test medium at the start.
Moisture:
The moisture content was 32.82% and 30.04% for the control and test medium at the start, 30.16% ~ 31.56% at the end.
Details on test conditions:
TEST SYSTEM
- Preparation of Test Medium:
2.49972 g of test item was weighed and mixed with 50g industrial sand. The treated sand was mixed thoroughly with proper artificial soil (dry weight was 2450 g). Proper distilled water (750 ml) was added to adjust the moisture content to about 30-35% of dry weight and mixed to be homogeneous. The complete mixture was moist but not so wet that water appears when the artificial soil was compressed. For each treated soil, four 750 g of the wet test medium were weighed and put into 4 labeled test containers.
A concurrent control group with four replicates maintained under identical conditions only without test item application would be performed in parallel. 50 g industrial sand was applied to properly pre-moistened artificial soil (dry weight was 2450 g). Proper distilled water (750 ml) was added to adjust the moisture content to about 30-35% of dry weight and mixed to be homogeneous. After the same treatment procedure as with the test medium, the sample was used as the control medium.
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 4
- No. of replicates per control: 4

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Preparation of Artificial Soil:
The artificial soil was prepared as follows:
a) 10 percent sphagnum peat (pH 5.5 to 6.0, no visible plant remains, finely ground, dried to measure moisture content that was determined to be 10.49%,);
b) 20 percent kaolin clay (kaolinite content above 30 percent);
c) 70 percent industrial Quartz sand (fine sand was dominant with more than 50 percent of the particles between 50 and 200 microns).
The dry constituents were blended in the correct proportions and mixed thoroughly in blender. According to above proportions, 2 replicates of 2500 g artificial soil were prepared for the test. For dosage of the test item, 50g of the sand fraction was used as carrier: after mixing, the treated sand sample was reintroduced to the test soil under mixing. After test item application, the moisture content was adjusted to about 30-35%.

OTHER TEST CONDITIONS
- Photoperiod: The light was kept continuous
- Light intensity: 521Lux ~ 674Lux (measured at the beginning and the end of the test)
- Relative humidity: 77% ~ 83%

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Measurement of body weight, soil moisture content and soil pH
At the start and at the end of the test, the individual weights of all live worms in each group were measured and recorded. The worms were washed prior to weighing (with distilled water) and the excess water was removed by placing the worms briefly on filter paper.
At the start and at the end of the test, soil moisture content was determined of each treatment medium and control medium. 1 replicate at the start and 4 replicates at the end. The moisture content was determined by drying a small sample at 105oC at least for 3 hours and re-weighing.
At the start of the test, soil pH was measured. 1 replicate would be measured in test group and control group. The method was as followed: wet soil was dried at room temperature for about 48 h. A suspension of the soil (containing 5 grams of soil) was then made up in five times its volume of a 0.01 M solution of analytical grade calcium chloride (CaCl2). The suspension was then shaken thoroughly for five minutes and then left to settle for at least 2 hours but not for longer than 24 hours. The pH of the liquid phase was then measured using a pH-meter.
- Observations
The mortality was assessed by emptying test medium onto a plate, sorting worms from the medium and testing their reaction to a mechanical stimulus at the front end at 7 and 14 days. After the 7-day assessment, worms and medium were replaced into the test containers. Any observed behavioral or pathological symptoms were recorded.

VEHICLE CONTROL PERFORMED: no

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 300, 1000 and 3000 mg/kg dry soil weight
- Results used to determine the conditions for the definitive study: There was no mortality or abnormal toxic signs observed on 7 and 14 days observation.
Nominal and measured concentrations:
Nominal: 1000 mg/kg dry soil weight
Reference substance (positive control):
yes
Remarks:
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:
During the exposure period, there was no mortality or abnormal signs in the control group, so the test was valid.
There were no mortality or toxic signs observed in the test group of 1000 mg/kg dry soil weight.
Results with reference substance (positive control):
The 14-days LC50 of the reference substance to earthworm is 44.79 mg/kg dry soil weight, with 95% confidence limits of 34.27-58.54 mg/kg dry soil weight.
Validity criteria fulfilled:
yes
Conclusions:
The 14-days LC50 of the test item to the earthworm is greater than 1000 mg/kg dry soil weight.
Executive summary:

This study was performed to assess the acute toxicity of the test item to the earthworm according to OECD Guideline 207 (Earthworm, Acute Toxicity Tests).

Based on the results of a preliminary test, the definitive study was conducted with limit concentration of 1000 mg/kg dry soil weight. A concurrent control group was conducted in parallel. For the test and control groups, four replicates were used with 10 worms in each replicate. Artificial soil was used in this study. The test duration was 14 days, assessment of mortality and abnormal signs were conducted at 7 and 14 days.

During the exposure period, there was no mortality or abnormal signs observed at control group and the test group of 1000 mg/kg dry soil weight.

According to the result, the 14-days LC50 of the test item to the earthworm is greater than 1000 mg/kg dry soil weight.

Endpoint:
toxicity to soil macroorganisms except arthropods: long-term
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
other:

Description of key information

Short-term study:

The 14-days LC50 of the test item to the earthworm is greater than 1000 mg/kg dry soil weight according to OECD Guideline 207.

Long-term study:

Equilibrium partitioning gives rise to a soil predicted no effect concentration which was undemanding.

With this in mind, further testing on the substance is considered not necessary.

Key value for chemical safety assessment

Additional information

According to Regulation (EC) No. 1907/2006, Annex X, section 9.4 column 2, Long-term toxicity testing shall be proposed by the registrant if the chemical safety assessment according to Annex I indicates the need to investigate further the effects on terrestrial organisms. In the absence of toxicity data for soil organisms, the equilibrium partitioning method may be applied to assess the hazard to soil organisms. Wet weight PNECs were calculated with using equilibrium partitioning as described in Guidance R.10 & R.16, conversion to dry weight was performed with factor of 1.13. A further Assessment Factor of 10 was also used to account for the substances high partition coefficient (logKow>5) This gave rise to a soil predicted no effect concentration which was undemanding and as such the chemical safety assessment should conclude safe use of the material. With this in mind, further testing on the substance is considered not necessary.