Reaction mass of 1,3-dioxane-5,5-dimethanol and 1,3-Propanediol, 2-(hydroxymethyl)-2-[(methoxymethoxy)methyl]-

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:

From 12 NOV 2015 to 10 DEC 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

GLP study conducted to the appropriate OECD Test Guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 216 (Soil Microorganisms: Nitrogen Transformation Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

no

Test organisms (inoculum):

soil

Total exposure duration:

28 d

Test temperature:

20 ± 2 °C (nominal)

Moisture:

At experimental starting the soil was adjusted to approximately 45 % of its maximum water holding capacity. All replicates were weighed once per week to check for water losses by evaporation (recommended maximum 5 %, actual 0.2 – 0.8 %). Compensation of demineralised water was done as necessary. Replicates were weighed for this procedure.

Organic carbon content (% dry weight):

42.8

Nitrogen content (% dry weight):

2.83

Details on test conditions:

TEST SYSTEM
- Testing facility: DR.U.NOACK-LABORATORIEN, Käthe-Paulus-Str.1, D-31157 Sarstedt, Germany
- Test container (type, material, size): Plastic boxes (volume 1.0 L, food grade) with perforated tops to enable gas exchange.
- Amount of soil: 400 g soil dry weight per replicate
- No. of replicates per concentration: Triplicates
- No. of replicates per control: Triplicates

SOIL INCUBATION
- Method: The soil was incubated in the above mentioned boxes. The tops of the boxes were perforated to enable gas exchange.

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographical reference of sampling site: Offenbach, “rechts der Landauer Str.“ Nr. 826/7, Rheinland-Pfalz, Germany, Gauß-Krüger-Coordinates: R-439683; H-5449554
- History of site: Cultures: 2011 - 2014: uncultivated, Fertilisation: 2015: none, 2014: 3500 kg/ha CaO (05.06.2014 and 24.09.2014) 3500 kg/ha CaO; 1463 kg/ha MgO (15.12.2014), 2013: none, 2012: none, 2011: none
- Treatments with pesticides or fertilizers: No crop protection products applied during the year of sampling and 4 preceding years.
- Depth of sampling: ca. 20 cm
- Soil texture: silty sand (uS) acc. to German DIN classification
- % sand: 2.0 - 0.63 mm: 2.7 ± 0.8 % dry weight, 0.63 - 0.2 mm: 30.3 ± 0.6 % dry weight, 0.2 - 0.063 mm: 24.6 ± 1.5 % dry weight
- % silt: 0.063 - 0.02 mm: 19.0 ± 1.8 % dry weight, 0.02 - 0.006 mm: 11.5 ± 0.6 % dry weight, 0.006 - 0.002 mm: 5.4 ± 0.8 % dry weight
- % clay: 6.6 ± 1.7 % dry weight
- pH (in water): 5.7 ± 0.6
- Initial nitrate concentration for nitrogen transformation test (mg nitrate/kg dry weight): 17.3 mg NO3-N/kg DW
- Maximum water holding capacity (in % dry weigth): 35.4 ± 1.5 g/100 g DW
- Cation exchange capacity (mmol/kg): 7.5 ± 0.9 meq / 100 g
- Pretreatment of soil: Prior to final moistening at test start, the soil was adjusted to about 42 % of its maximum water holding capacity with demineralised water. Drying out of the soil was prevented by moistening with demineralised water as necessary. The soil was checked for a detectable microbial biomass (result expressed in terms of percentage of total organic carbon) and the amount of total inorganic nitrogen. The soil amounts were amended with powdered lucerne-green-grass-meal (0.5 % of soil dry weight). The C/N ratio was between 12/1 and 16/1. A ratio of 5 g Lucerne per kg of soil (dry weight was used. Content of total inorganic nitrogen: 2.83 % (dry weight) Content of total organic carbon: 42.8 % (dry weight) C/N-ratio: 15.1
- Storage (condition, duration): The soil was stored for 14 days (2015-10-07 to 2015-10-21) in the dark at 6 ± 2 °C in a climatic room (TE1200, VIESSMANN).
- Initial microbial biomass as % of total organic C: 2.48

DETAILS OF PREINCUBATION OF SOIL (if any): the soil was pre-incubated at room temperature (ca. 20 °C) for 22 days (2015-10-21 to 2015-11-12) to adapt the micro-organisms to test conditions before the start of the study

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Measurements of nitrate concentrations were carried out after 0, 7, 14 and 28 days.The pH values and water contents were determined on day 0 and 28. The room temperature was measured and recorded continuously with a thermohygrograph.

RANGE-FINDING STUDY
- Test concentrations: 10, 100, 1000 mg/kg soil DW
- Results used to determine the conditions for the definitive study: Based on the results of the preliminary study, the test concentrations for the definitive study were selected: 10, 31.6, 100, 316, 1000 mg /kg soil dry weight (spacing factor √10)

Nominal and measured concentrations:

Nominal concentrations: 10, 31.6, 100, 316, 1000 mg/kg dw of soil

Reference substance (positive control):

yes

Remarks:

Cyanoguanidine

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/kg soil dw

Basis for effect:

nitrate formation rate

Duration:

7 d

Dose descriptor:

other: LOEC

Effect conc.:

> 1 000 mg/kg soil dw

Basis for effect:

nitrate formation rate

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

316 mg/kg soil dw

Basis for effect:

nitrate formation rate

Duration:

14 d

Dose descriptor:

other: LOEC

Effect conc.:

1 000 mg/kg soil dw

Basis for effect:

nitrate formation rate

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

316 mg/kg soil dw

Basis for effect:

nitrate formation rate

Duration:

28 d

Dose descriptor:

other: LOEC

Effect conc.:

1 000 mg/kg soil dw

Basis for effect:

nitrate formation rate

Duration:

28 d

Dose descriptor:

EC25

Effect conc.:

> 1 000 mg/kg soil dw

Basis for effect:

nitrate formation rate

Key result

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/kg soil dw

Basis for effect:

nitrate formation rate

 

Nitrate-N Content                                 Inhibition [%] compared to control
Test concentration (mg/kg soil dry weight)	0 d	7 d	14 d	28 d
10	0	-9	-3	-1
31.6	-5	-16	-11	-9
100	1	-6	-2	-1
316	1	-4	2	1
1000	6	6	11	16

negative values = increase

 

 

Nitrate-N Formation Rate Inhibition [%] compared to control
Test concentration (mg/kg soil dry weight)		7 d	14 d	28 d
10		-22	-5	-2
31.6		-31	-16*	-10
100		-15	-4	-2
316		-11	3	1
1000		5	14*	20*

* Statistically significant difference compared to control (ANOVA, p ≤ 0.05)

negative values = increase

Validity criteria fulfilled:

yes

Conclusions:

The effects of the test item on the metabolic activity of the nitrogen-N (nitrate) formation rate were measured on the day of treatment (day 0) and subsequently after 7, 14 and 28 days.
After 14 and 28 days of exposure to POLYOL PX, a significant inhibition of the microbial nitrate transformation was observed for the test item concentration 1000 mg/kg soil dry weight. The mean inhibition on day 28 compared to the control was 20 %. The EC25 and EC50-values could not be determined since no inhibition effects ≥ 25 or 50 % were detected. Therefore the EC25-value and EC50-value were determined to be > 1000 mg test item/kg soil dry weight.
The corresponding no-observed effect concentration (NOEC) was 316 mg POLYOL PX/kg soil dry weight and the LOEC was determined to be 1000 mg POLYOL PX/kg soil dry weight.

Executive summary:

The effects of Polyol PX on the metabolic activity of soil microorganisms were determined according to OECD Guideline 216 (2000). The approach for non-agrochemical substances, which entails a dose-response test design and focuses primarily on inhibitory effects was adopted in this study.

 

The test item was applied via quartz sand at nominal concentrations of 1000, 316, 100, 31.6, 10 mg/kg soil DW (spacing factor √10). Untreated field soil, adjusted to a moisture content corresponding to nominally 45% of its maximum water holding capacity and mixed with a source of organic nitrogen (lucerne green grass meal), was tested as the control under the same trst conditions as the test item replicates. Plastic boxes (V=1.0 L) with perforated tops to enable gas exchange and filled with 400g soil DW were used as test vessels.

 

The effects of the test item on nitrogen transformation by soil microflora were determined by comparing rates of formation of the terminal transformation product, nitrate-nitrogen (NO3-/N), in soil treated with Polyol PX against the rate observed in the untreated control. Measurements of nitrate-nitrogen concentrations in soil were made in all treatments and the control on the day of treatment application (day 0) and after 7, 14 and 28 days.

 

After 14 and 28 days of exposure to Polyol PX, a significant inhibition of the microbial nitrate transformation was observed for the test item concentration of 1000 mg/kg soil DW. The mean inhibition on day 28 compared to the control was 20%. The EC25 and EC50 values could not be determined since no inhibition effects ≥25% or 50% were detected. Therefore, the EC25 and EC50 values were determined to be >1000 mg/kg soil DW.

 

The corresponding NOEC was 316 mg/kg soil DW and the LOEC was determined to be 1000 mg/kg soil DW.

Description of key information

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

 

After 14 and 28 days of exposure to POLYOL PX, a significant inhibition of the microbial nitrate transformation was observed for the test item concentration 1000 mg/kg soil dry weight. The mean inhibition on day 28 compared to the control was 20 %. The EC25 and EC50-values could not be determined since no inhibition effects ≥ 25 or 50 % were detected. Therefore the EC25-value and EC50-value were determined to be >1000 mg test item/kg soil dry weight.

 

The corresponding no-observed effect concentration (NOEC) was 316 mg POLYOL PX/kg soil dry weight and the LOEC was determined to be 1000 mg POLYOL PX/kg soil dry weight

Key value for chemical safety assessment

Short-term EC50 for soil microorganisms:

1 000 mg/kg soil dw

Long-term EC10 or NOEC for soil microorganisms:

316 mg/kg soil dw