3a,4,7,7a-tetrahydro-4,7-methanoindene

Toxicity to soil microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to soil microorganisms

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13/05/2016 - 28/11/2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 216 (Soil Microorganisms: Nitrogen Transformation Test)

Deviations:

yes

Remarks:

Deviations were not considered to imact the outcome, quality or integrity of the study

Principles of method if other than guideline:

Deviations:
The soil was stored at 6 ± 2°C instead of 4 ± 2°C as the climatic chamber for storage of amounts of >5 kg cannot be adjusted to lower temperatures (technical reasons).
Extraction and determination of nitrate was carried out on day 29 instead of day 28 due to organizational reasons. This deviation was considered to have no impact on the quality or integrity of the study.

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Test item (as specified in the report): Dicyclopentadiene
Batch number: 1518148 (LIMS Sample manager report date 2016-02-17)
Cas number: 77-73-6
Active substance / content: Dicyclopentadiene / 92.66%
pH: Not applicable
Appearance: Colourless liquid
Water solubility <= 0.01%

Analytical monitoring:

yes

Remarks:

A field fresh, silty sand soil was used in the study. Nominal soil parameters were: Sand content 50-75 % pH value 5.5-7.5 Organic carbon content 0.5-1.5 % Microbial biomass (expressed as carbon content) at least 1% of the total soil organic carbon.

Details on sampling:

- Soil site Offenbach, "rechts der Landauer Str." Nr. 826/7, Rheinland-Pfalz, Germany
- Sampling date: 02/02/2016
- Pesticides: No crop protection products applied during the year of sampling and 4 preceding years.
- Soil handling: The soil was manually cleared of large objects and then sieved to a particle size up to 2mm.. The maximum water holding capacity and the pH value were determined.
- Sample clean-up: 10 mL of each filtered extract was cleaned via Ce-SPE-cartridges to remove dissolved and coloured organic matter which could interfere with the photometric determination. Conditioning of the cartridges was done with 2 x 2.5 mL methanol and thereafter with 2 x 2.5 mL demineralised water. Care was taken not to allow the cartridges to dry out. After conditioning, the sample was applied. The first 2.5 mL of each cleaned extract was rejected. The following volumes were stored in reagent tubes.

Vehicle:

no

Details on preparation and application of test substrate:

Soil: Field fresh, silty sand soil (LUFA soil 2.3 - LUFA Speyer, Obere Langgasse 40, 67346 Speyer, Germany).
Sample site: Site was not treated with crop protection products for at least 1 year before sampling, organic fertiliser for at least 6 months before sampling or mineral fertiliser for at least 3 months before sampling.
Preparation: Soil was sieved to 2 mm and adjusted to approximately 42% of its maximum Water Holding Capacity. Soil was checked for detectable microbial biomass and amended with lucerne-grass-green-meal (0.5% of soil dry weight).
Storage: Soil was stored for 92 days at 6 ± 2°C in a climatic room before pre-incubation at room temperature (approximately 20°C) for 24 hours before exposure.
Application: Respective amounts of test item were pipetted onto quartz sand (1% of total soil amount per treatment), mixed thoroughly and applied to the surface of the soil. Soil was adjusted to 45% of the maximum water holding capacity (WHCmax) with demineralised water and mixed with an electric mixer before distribution into the replicates.
Soil parameters:
Sampling depth: Approximately 20 cm
pH 5.7 ± 0.6
Soil dry weight before application 87.0 g/100 g soil
Maximum water holding capacity: 35.4 ± 1.5 g/100 g dry weight (DW)
Sand: 57.6%
Silt: 35.9%
Clay: 6.6%
Microbial biomass: 3.78 % total organic carbon
CEC: 7.5 meq/100 g

Test organisms (inoculum):

soil

Total exposure duration:

29 d

Remarks:

Extraction and determination of nitrate was carried out on day 29 instead of day 28 due to organizational reasons. This deviation was considered to have no impact on the quality or integrity of the study.

Test temperature:

Room temperature throughout test duration
nominal: 20 ± 2°C
measured: 21 - 22°C

Moisture:

At the start of the experiment premoistened soil was adjusted to approximately 45% of the maximum water holding capacity. All replicates were checked once per week for losses. Demineralised water was added as neessary.
Moisture: 41.9-43.4% maximum water holding capacity

Details on test conditions:

A field fresh, silty sand soil (LUFA-soil 2.3) was used in the study.
- Nominal soil parameters were:
Sand content 50-75%
pH value 5.5 - 7.5
Organic carbon content 0.5 - 1.5%
Microbial biomass (expressed as carbon content) at least 1% of the total soil organic carbon.

-Soil storage:
The soil was stored for 92 days in the dark at 6 ± 2°C in a climatic room (TE1200, Viessmann). Subsequently, the soul was pre-incubated at room temperature (ca. 20°C) for 24 days before experimental starting to guarantee a temperature adaption of the microorganisms.

- Preliminary study (non-GLP):
Yes, 1, 10, 100 mg/kg soil dry weight

-Test concentrations:
Based on the results of the preliminary study, the following concentrations were tested: 1000, 500, 250, 125, 62.5 mg/kg soild dry weight

- Replicates:
In triplicates for each test concentration and the control

- Soil amount per replicate:
400g soil dry weight

- Test vessels:
Plastic boxes (volume 1.0L, food grade) with perforated tops to enable gas exchange.

- Application:
The respective test item amounts were pipetted onto quartz and sand (1% of the total soil amount per treatment), mixed thoroughly and applied to the surface of the soil. Additional demineralized water was added to adjust the humidity of the artificial soil to 45% of the maximum water holding capacity. Afterwards, the soil was mixed with an electric mixer to ensure a homogeneous distribution of the test item in the soil. Subsequently, the soil was distributed to the replicates.

- Aeration:
The soul was incubated in the above mentioned boxes. The tops of the boxes were perforated to enable gas exchange.

- Photoperiod: Dark

- pH: 6.73-7.00

- soil dry weight: 86.8-87.1%

- Effect parameters measured: Measurements of inorganic nitrate were carried out on days 0, 7, 14 and 29. Nitrate was extracted from soil with a mineral salt medium (potassium chloride) and cleaned with C18-SPE cartridges (conditioned with methanol and demineralised water). Nitrate-nitrogen concentrations were determined photometrically (588 nm). Potassium nitrate was prepared in demineralised water as an extraction standard. LOQ for nitrate-N: 1.74 mg NO3-N/kg SDW.

Nominal and measured concentrations:

Nominal: 1000, 500, 250, 125, 62.5 mg/kg soil dry weight
Control: Untreated soil

Reference substance (positive control):

yes

Remarks:

Cyanoguanidine

Key result

Duration:

29 d

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

nitrate formation rate

Details on results:

No inhibiting effects on the nitrification potential were seen at the highest concentration tested 1000 mg/kg soil dry weight. Enhancing effects in respect to an increase of the nitrification potential could be observed in a concentration dependent manner, trailing off over the exposure time.

Results with reference substance (positive control):

Reference substance concentration of 50 mg/kg soil dry weight saw 82% nitrate-N formation rate compared to the untreated control. At a concentration of 100 mg/kg soil dry weight there was a 92% nitrate-N formation rate compared to the untreated control.

Reported statistics and error estimates:

Normality and equal variance were tested (p=0.05) then one way analysis of variance (ANOVA) was carried out to determine statisticially significant differences between the treatments and the control replicates.
No statistical calculations were performed to derive EC values as no inhibition was detected.

N/A

Validity criteria fulfilled:

yes

Remarks:

Variation between the control replicates was <15% at days 0, 7, 14 and 29 for determination of the nitrate-N content. In detail, variation of nitrate-N contents between control replicates were 7% at day 0, 0% at day 7, 3% at day 14 and 29.

Conclusions:

DPCD showed no inhibiting effects on the nitrification potential up to a concentration of 1000 mg/kg SDW. Therefore, the NOEC can be considered to be 1000 mg/kg SDW and the EC10 can be considered higher than 1000 mg/kg SDW.

Executive summary:

The effect of DCPD on the nitrification of soil microorganisms was determined in a GLP-compliant study following OECD guideline 216. No inhibiting effect on the nitrification potential was observed up to a concentration of 1000 mg/kg SDW, the highest concentration tested. The NOEC is therefore considered to be 1000 mg/kg SDW.

Description of key information

DPCD showed no inhibiting effects on the nitrification potential up to a concentration of 1000 mg/kg SDW. The NOEC can thus be considered equal or higher than 1000 mg/kg SDW and the EC₁₀ can be considered higher than 1000 mg/kg SDW.

Key value for chemical safety assessment

Long-term EC10 or NOEC for soil microorganisms:

1 000 mg/kg soil dw

Additional information

The effect of DCPD on the nitrification of soil microorganisms was determined in a GLP-compliant study following OECD guideline 216. No inhibiting effect on the nitrification potential was observed up to a concentration of 1000 mg/kg SDW, the highest concentration tested. The NOEC is therefore considered to be 1000 mg/kg SDW.