Registration Dossier

Ecotoxicological information

Toxicity to soil microorganisms

Currently viewing:

Administrative data

Endpoint:
toxicity to soil microorganisms
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2015-04-01 to 2015-04-29
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study according to OECD guidelines
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:
no
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:
Tetraethylenepentamine, TEPA is a pale yellow, clear liquid.
Purity 96.4%
Expiry 2015-09-19
Batch Number P1027
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 dissolved in demineralised water. Afterwards the test item solutions were 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 500, 250, 125, 62.5 and 31.3 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 temperature range - 18 - 22°C, measured temperature range 20-22.5°C. The measured temperature as above 22°C for 48 hours, however this minor deviation is not considered to have affected the outcome of the study.
Moisture:
Start of exposure period (day 0) - 43.5 – 43.80 % of maximum water holding capacity, end of exposure period (day 28) - 43.6 - 44.1 % of maximum water holding capacity.
Organic carbon content (% dry weight):
The measured organic carbon of the soil is 0.63% - LUFA soil 2.3 - Batch number F2.30915
Nitrogen content (% dry weight):
Measured total inorganic carbon = 15.5 mg/kg dw - LUFA soil 2.3 - Batch number F2.30915. The % dry weight is therefore 0.155%
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 test concentrations were 500, 250, 125, 62.5 and 31.3 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.:
> 500 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.:
500 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
nitrate formation rate
Details on results:
The rates of nitrate formation were consistently higher in all the TEPA treatments than in the untreated control at all timepoints throughout the study. Consequently, there was no evidence that exposure to TEPA inhibited the nitrogen transformation activity of soil microflora at the range of concentrations applied. The EC50 based on inhibition of nitrogen transformation processes could therefore not be determined reliably, but it exceeded 500 mg TEPA/kg soil dry weight, the highest concentration applied in the definitive test. The corresponding no-observed effect concentration (NOEC) was 500 mg TEPA/kg soil dry weight.
The cause of the dose-related increase in nitrate formation observed across the range of test item treatments is unknown. One explanation may be that TEPA stimulated the breakdown of the lucerne meal substrate and accelerated the mineralisation of plant-derived organic nitrogen relative to the control. Alternatively (or additionally), partial breakdown of the test item may have released nitrogen for mineralisation; the nitrate-nitrogen concentrations in the TEPA treatments at the end of the test exceeded the day 28 nitrate-nitrogen concentration in the control by amounts that are all within the range of the applied TEPA treatments expressed as N-equivalent concentrations. Discrimination between these two possibilities is not possible without making substantial alterations to the study design that are beyond the requirements and purpose of the test guideline.
Results with reference substance (positive control):
Inhibition compared to Control was calculated as; 68%, 87%, 86% at 7 d, 14d and 28d respectively for 50 mg/kg soil dry weight. 97%, 96%, 96% at 7 d, 14d and 28d respectively for 100 mg/kg soil dry weight.
Reported statistics and error estimates:
One Way Analysis of Variances (ANOVA) and DUNNETT'S test, if possible was carried out for the determination of statistically significant differences compared to control replicates. When running a One Way Analysis of Variances 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.

Any other information on results incl. tables

Table 1. 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

31.3

-43*

-29*

-10

62.5

-46*

-36*

-19*

125

-67*

-62*

-39*

250

-74*

-90*

-71*

500

-133*

-130*

-117*

*) Statistically significant difference compared to control (ANOVA, p0.05)

positive values = inhibition negative values = increase


Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The effects of Tetraethylenepentamine, TEPA 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 28 day EC50 value was >500 mg/kg soil dry weight. The corresponding no-observed effect concentration (NOEC) was 500 mg TEPA/kg soil dry weight.
Executive summary:

The effects of Tetraethylenepentamine, TEPA on the metabolic activity of the nitrogen-N formation rate (nitrate) soil micro-organisms were determined according to OECD Guideline 216 (2000) over a 28 day period. Nominal test concentrations were 31.3, 62.5, 125, 250 and 500 mg/kg soil dry weight. Effects were recorded 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. The rates of nitrate formation were consistently higher in all the TEPA treatments than in the untreated control at all timepoints throughout the study. Consequently, there was no evidence that exposure to TEPA inhibited the nitrogen transformation activity of soil microflora at the range of concentrations applied. The 28 day EC50 value was >500 mg/kg soil dry weight. The corresponding no-observed effect concentration (NOEC) was 500 mg TEPA/kg soil dry weight. Test validity criteria were fulfilled.