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Ecotoxicological information

Toxicity to soil microorganisms

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Administrative data

Endpoint:
toxicity to soil microorganisms
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2015-03-19 to 2015-04-17
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2015
Report Date:
2015

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 216 (Soil Microorganisms: Nitrogen Transformation Test)
Deviations:
yes
Remarks:
The soil was stored at 6 ± 2 °C instead of 4 ± 2 °C due to organisational reasons. This minor deviation is not considered to have had any effect on the outcome of the study.
Principles of method if other than guideline:
N/A
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: liquid
Details on test material:
Soybeanoil, epoxidized is a clear, viscous, colourless liquid with 100% purity.
Batch number 2014234102
Expiry date 2015-12-02
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
N/A

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
The effects of the test item on the metabolic activity of the nitrogen-N formation rate (nitrate) were measured on the day of treatment (day 0) and after 7, 14 and 28 days.

Test substrate

Vehicle:
no
Details on preparation and application of test substrate:
The respective test item amounts were weighed out for each test item concentration and blended thoroughly with quartz sand (1 % of the entire soil amount per concentration). Afterwards the test item - quartz sand mixture was mixed carefully into the soil with a mixer to ensure a homogeneous distribution of the test item in the soil. Thereafter the soil was distributed to the replicates, there were three replicates per test concentration. Nominal test concentrations were 1000 - 500 - 250 - 125 - 62.5 mg/kg soil dry weight (nominal concentrations).

Test organisms

Test organisms (inoculum):
soil

Study design

Total exposure duration:
28 d

Test conditions

Test temperature:
Nominal test temperature range - 18 - 22 °C, measured range 20 - 21 °C
Moisture:
Start of exposure period (day 0) - 47.7 - 48.0 % of dry weight, end of exposure period (day 28) - 46.2 - 48.0 % of dry weight
Details on test conditions:
Test chambers were plastic boxes (volume 1.0L, food grade) with perforated tops to enable gas exchange. Test chambers were kept in continuous darkness. Test concentrations were replicated in triplicate. 400 g soil dry weight was used per replicate. At experimental start the premoistened soil was adjusted to approximately 50% of its maximum water holding capacity. All replicates were checked once per week for water losses by evaporation (recommended maximum 5%, actual 0.2 - 1.3%). Compensation with demineralised water was done.
Nominal and measured concentrations:
Nominal concentrations were 1000 - 500 - 250 - 125 - 62.5 mg/kg soil dry weight.
Reference substance (positive control):
yes
Remarks:
Cyanoguanidine

Results and discussion

Effect concentrationsopen allclose all
Duration:
28 d
Dose descriptor:
EC50
Effect conc.:
402 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
nitrate formation rate
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
< 62.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
nitrate formation rate
Details on results:
After 7 days of exposure to Soybeanoil, epoxidised a significant inhibition of the microbial nitrate formation rate was observed for the test item concentrations 62.5, 125 and 250 mg/kg soil dry weight. For the test item concentrations 500 and 1000 mg/kg soil dry weight no nitrate formation rate was determined since the nitrate-N content was under the limit of quantification (LOQ). After 14 days of exposure a significant inhibition of the microbial nitrate formation rate was observed for the test item concentrations 125, 250 and 500 mg/kg soil dry weight. No nitrate formation rate was determined for the test item concentration 1000 mg/kg soil dry weight, since the nitrate-N content was < LOQ. After 28 days of exposure a significant inhibition of the nitrate formation rate was determined at all test item concentrations.

After 7 days of exposure the EC25-value for inhibition of the nitrate-N formation rate in soil was under the lowest test item concentration of 62.5 mg/kg soil dry weight. The EC50-value was determined to be 76.6 mg/kg soil dry weight.

After 14 days of exposure the EC25- and EC50-values for inhibition of the nitrate-N formation rate were 109 and 169 mg/kg soil dry weight, respectively.

After 28 days of exposure the EC25-value for inhibition of the nitrate-N formation rate in soil was 182 mg/kg soil dry weight. The EC50-value was 402 mg/kg soil dry weight.
Results with reference substance (positive control):
Cyanoguanidine is tested once per year as toxic reference with 50 and 100 mg/kg soil dry weight.

Inhibition [%] compared to Control
Day 7 14 28
Cyanoguanidine 50 mg/kg soil dry weight 68* 87* 86*
Cyanoguanidine 100 mg/kg soil dry weight 97* 96* 96*
* difference to control ≥25 %
Reported statistics and error estimates:
One Way Analysis of Variances (ANOVA) and DUNNETT'S test were carried out for the determination of statistically significant differences compared to control replicates. When running the tests a Normality test and an Equal Variance test was done first. P-values for both Normality and Equal Variances test are 0.05. The ą-value for ANOVA and DUNNETT'S test (acceptable probability of incorrectly concluding that there is a difference) is ą = 0.05. A statistically significant difference is reported for all test concentrations at all sampling points (except 62.5 mg/kg soil dry weight at 14 days) for inhibition of nitrogen formation compared to the control.

EC25 and EC50-values were calculated by sigmoidal dose-response and linear regression, respectively

Any other information on results incl. tables

Table 1. Nitrate-N Formation Rate: NOEC-, LOEC and ECx-Values

 

Day 7

Day 14

Day 28

mg/kg soil dry weight

NOEC

<62.5

62.5

<62.5

LOEC

62.5

125

62.5

EC25

<62.5

109

182

95 % confidence interval

-

<62.5 - 145

154 - 213

EC5o

76.6

169

402

95%confidence interval

<62.5 - 89.1

135 - 206

369 - 442

Table 2. Inhibition of Inorganic-N Formation Rates

Nitrate-N Formation Rate

Test concentration Inhibition [%] compared to control

[mg/kg soil dry weight]

Inhibition [%] compared to Control

7d

14d

28d

62.5

39*

13

11*

125

77*

32*

17*

250

#

71*

34*

500

n.d.

#

59*

1000

n.d.

n.d.

93*

 

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The effects of Soybeanoil, epoxidized on the metabolic activity of soil micro-organisms was determined according to OECD Guideline 216 (2000) over a 28 day period. The effects of the test item on the metabolic activity of the nitrogen-N formation rate (nitrate) was measured on the day of treatment (day 0) and after 7, 14 and 28 days. The 7 day EC50 value was 76.6 mg/kg soil dry weight. The 14 day EC50 value was 169 mg/kg soil dry weight. The 28 day EC50 value was 402 mg/kg soil dry weight.
Executive summary:

The effects of Soybeanoil, epoxidized on the metabolic activity of the nitrogen-N formation rate (nitrate) soil micro-organisms was determined according to OECD Guideline 216 (2000) over a 28 day period. Nominal test concentrations were 62.5, 125, 250, 500 and 1000 mg/kg soil dry weight. The effects of Soybeanoil, epoxidized on the metabolic activity of the nitrogen-N formation rate (nitrate) was measured on the day of treatment (day 0) and after 7, 14 and 28 days. Untreated soil was tested as the control under the same test conditions as the test item replicates. After 7 days of exposure the EC25-value for inhibition of the nitrate-N formation rate in soil was under the lowest test item concentration of 62.5 mg/kg soil dry weight. The EC50-value was determined to be 76.6 mg/kg soil dry weight with a corresponding NOEC of <62.5 mg/kg dw. After 14 days of exposure the EC25- and EC50-values for inhibition of the nitrate-N formation rate were 109 and 169 mg/kg soil dry weight, respectively with a corresponding NOEC of 62.5 mg/kg dw. After 28 days of exposure the EC25-value for inhibition of the nitrate-N formation rate in soil was 182 mg/kg soil dry weight. The 28 day EC50-value was 402 mg/kg soil dry weight with corresponding LOEC and NOECs of 62.5 and <62.5 mg/kg dw soil respectively. Test validity criteria were fulfilled

.