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Ecotoxicological information

Toxicity to soil microorganisms

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Administrative data

Endpoint:
toxicity to soil microorganisms
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2007
Report Date:
2007

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 217 (Soil Microorganisms: Carbon Transformation Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.22 (Soil Microorganisms: Carbon Transformation Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Creosote Grade B
- Physical state: brown liquid
- Analytical purity: 100% creosote (Creosote Grade B according to EU standard EN 13991, August 2003)
- Impurities (identity and concentrations): not applicable
- Composition of test material, percentage of components: complex mixture of numerous aromatic hydrocarbons, phenolics,
nitrogen-containing heterocycles and others

- Expiration date of the lot/batch: 2047-03-09
- Storage condition of test material: at room temperature, protected from moisture and light
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
--

Sampling and analysis

Analytical monitoring:
no
Details on sampling:
--

Test substrate

Vehicle:
no
Details on preparation and application of test substrate:
APPLICATION OF TEST SUBSTANCE TO SOIL
- Method: The test substance was weighed out on quartz sand and mixed homogeneously. The amount of quartz sand corresponds to 1 % of the bulk sample (= 10 g quartz sand / kg soil dry weight). Afterwards the mix of the test substance and quartz sand, the soil and demineralized water (to achieve a nominal moisture content of 50 % of the maximum water holding capacity) were mixed thoroughly with a long-handled blender for at least three minutes. Care was taken to insure a homogeneous distribution of the test item in the soil. Afterwards the soil was distributed to the replicates.

Test organisms

Test organisms (inoculum):
soil

Study design

Total exposure duration:
28 d

Test conditions

Test temperature:
19 - 21°C
Moisture:
49.5% of the maximum water holding capacity
Details on test conditions:
TEST SYSTEM
- Testing facility: Dr. U. Noack Labotatorien, Käthe-Paulus- Straße 1, 31157 Sarstedt, Germany
- Test container (type, material, size): Plastic boxes (volume 0.5 L, food grade) with perforated tops to enable gas exchange
- Amount of soil:
- No. of replicates per concentration: 3
- No. of replicates per control: 3

SOIL INCUBATION
- Method: bulk

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Soil was provided by Landwirtschaftliche Untersuchungs- und Forschungsanstalt (LUFA) Speyer, Germany. Soil was standard soil type 2.3.
- Geographical reference of sampling site: Offenbach, Im Bildergarten Nr. 586, Germany
- History of site: 2007: uncultivated; 2006: uncultivated; 2005: pumpkin; 2004: pumpkin; 2003: pumpkin;
- Vegetation cover: no data
- Treatments with pesticides or fertilizers: no organic fertilization; 2005: 300 kg/ha Nitrophoska Spezial (12 % N, 12 % P2O5, 17 % K2O); 2004: 400 kg/ha Nitrophoska Spezial (12 % N, 12 % P2O5, 17 % K2O); 2003: 400 kg/ha Nitrophoska (15 % N, 5 % P2O5, 20 % K2O)
- Accidental contamination: no
- other: no crop protection products applied during sampling year and 4 former years.
- Depth of sampling: ca. 20 cm
- Soil texture: loamy sand (lS)
- % sand: 57.4
- % silt: 31.5
- % clay: 8.9
- Soil taxonomic classification: no data
- Soil classification system: lS acc. to German DIN cclassification
- pH (in water): ca. 6.7
- Maximum water holding capacity (in % dry weigth): 34.9 g/100 g dw
- Cation exchange capacity: 9 mVal/100 g
- Pretreatment of soil: the soil was manually cleared of large objects and sieved to a particle size of 2 mm (carried out by LUFA Speyer). The maximum water holding capacity and the pH-value were determined by LUFA Speyer. The soil moisture content was determined and the soil was adjusted to 45% of its maximal water holding capacity.
- Storage (condition, duration): in the dark at 4 ± 2°C in a climatic room for 61 days.
- Initial microbial biomass as % of total organic C: 4.0

DETAILS OF PREINCUBATION OF SOIL (if any): The soil was preincubated at room temperature (ca. 20°C) for 7 days before the experimental start to guarantee a temperature adaption of the micro-organisms.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): respiratory rates were measured at day 0, 7, 14, and 28. pH and water content were determined on days 0 and 28. All replicates were checked at least once per week for losses by evaporation (recommended maximum 5 %; actual 0.2 to 0.8 %). Replicates were weighed for this procedure.

RANGE-FINDING STUDY
- Test concentrations: 1, 10, 100, and 1000 mg/kg dw
- Results used to determine the conditions for the definitive study: respiratory rate was inhibited after 28 days by 2% at 100 mg/kg dw but it was stimulated by 35% at 1000 mg/kg dw.
Nominal and measured concentrations:
Nominal concentrations: 0, 10, 31.6, 100, 316, and 1000 mg/kg dw
Reference substance (positive control):
yes
Remarks:
Dinoterb (2-tert-butyl-4,6-dinitrophenol, 98%)

Results and discussion

Effect concentrationsopen allclose all
Duration:
28 d
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
respiration rate
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
respiration rate
Remarks on result:
other: highest concentration tested
Results with reference substance (positive control):
Inhibition of respiration rate
day 0 7 14 28
% inhibition 17 19 42 58
Reported statistics and error estimates:
One Way Analysis of Variance (ANOVA) and DUNNETT’s test were carried out for the determination of statistically significant differences compared to control replicates. When running a One Way Analysis of Variance, a Normality test and an Equal Variance test were done first. P-values for both Normality and Equal Variance test are 0.05. The alpha-value for ANOVA and DUNNETT’s test (acceptable probability of incorrectly concluding that there is a difference) is alpha = 0.05.

Any other information on results incl. tables

Changes [%] of the Respiration Rate in Comparison to the Untreated Control

 

Nominal Test Concentration
[mg/kg DW]

Respiration Rate [%]

0 d

7 d

14 d

28 d

10

-1

7

13

4

31.6

8

-9

3

1

100

16

-28

-15

-9

316

29

-77

-22

-11

1000

24

-179

-107

-87

 

negative values = stimulation, positive values = inhibition

 

 

In this study, Creosote Grade B caused only transient inhibitory effects ≤29% inhibition on the day of application. Seven days post-application, a strong stimulation was found at test concentrations of ≥100 mg/kg, two weeks post-application at test concentrations of ≥316 mg/kg and four weeks after application at the test concentration of 1000 mg/kg. Therefore, under normal conditions, Creosote Grade B is not expected to lead to any long-term detrimental inhibitions of carbon transformation in soil when applied at a maximum of 1000 mg/kg DW.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
In this study, Creosote Grade B caused only transient inhibitory effects ≤ 29% inhibition on the day of application. Seven days post-application a strong stimulation was found at test concentrations of ≥ 100 mg/kg, two weeks post-application at test concentrations of ≥ 316 mg/kg and four weeks after application at the test concentration of 1000 mg/kg. Therefore, under normal conditions, Creosote Grade B is not expected to lead to any long-term detrimental inhibitions of carbon transformation in soil when applied at a maximum of 1000 mg/kg dw.