Ziram

Toxicity to soil microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to soil microorganisms

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1 February 1998 - 1 June 1999

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Study performed with product.

Qualifier:

according to guideline

Guideline:

BBA Part VI, 1-1

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on preparation and application of test substrate:

- Prior to the application, the soil was enriched with ground lucerne meal (0.5% of the soil dry weight). The test substance was applied at an application rate referring to 4kg/ha and 40 kg/ha at a penetration depth of 5 cm and a specific gravity of 1.5 g/cm3. The water content was adjusted to 40% (soil 1) and 55% (soil 2) of its maximum water holding capacity (WHC). The samples were mixed homogeneously with the lucerne meal. The reference substance was applied at a concentration of 20L/ha (5x concentration)

Test organisms (inoculum):

soil

Total exposure duration:

56 d

Remarks:

28 d - Nitrogen turnover

Test temperature:

18 - 22 °C

Moisture:

Adjusted to 40 % (soil 1) and 55 % (soil 2) of the maximum soil water holding capacity (MWC).

Details on test conditions:

TEST SYSTEM
- Test container: 1 L glass bottles
- Amount of soil: 800 g
- No. of replicates per concentration: 3
- No. of replicates per control: 3
- No. of replicates reference substance: 3

EFFECT PARAMETERS MEASURED : inorganic nitrogen content at 3 hours, 14 and 28 days

Nominal and measured concentrations:

Nominal: 4 kg product/ha (3.04 kg a.s./ha, 1 × recommended application rate) and 40 kg product/ha (30.4 kg a.s./ha, 10 × recommended application rate).

Reference substance (positive control):

yes

Duration:

56 d

Dose descriptor:

NOEC

Effect conc.:

>= 20.3 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

nitrate formation rate

Remarks on result:

other: Recalculated based on target substance concentration in formulation and using a default depth of 10 cm and soil density of 1500 gk/m3

Duration:

56 d

Dose descriptor:

NOEC

Effect conc.:

>= 40 kg/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

nitrate formation rate

Duration:

56 d

Dose descriptor:

NOEC

Effect conc.:

>= 30.4 kg/ha

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

nitrate formation rate

Details on results:

Impact on soil nitrogen turnover is considered as negligible

Conclusions

There were no dinstinct effects of the test substance on the nitrogen turnover activities of soil microorganisms in soil type 1 and 2 in comparison to the control (deviation less than 15%). The ammonium and nitrate contents, expressed as N_min in the treatment groups were not signifincantly different from the control in both soil types within the 28 days incubation period.

Therefore, the impact on soil nitrogen turnover is considered as negligible even at the 10x dosage rate of Ziram 76% WG.

Short term respiration rate in the treatment groups of both soil types was not significantly different from control (deviation less than 15%).

Therefore, the impact on soil respiration is considered as negligible even at the 10x dosage of the highest recommended Ziram 76%WG application rate.

Classification

Based on the results obtained within the study, Ziram 76% WG can be classified to group I (nitrogen turnover, deviation effects within +/- 15% compared with the control group during 28 days) and II (short-term respiration, deviation effects within +/- 15% compared with the control during 56 days), following the standard of assessment of BBA guideline part VI, 1 -1.

Therefore, the impact on soil nitrogen turnover and short term respiration activities can be assessed as negligible even at the 10x dosage rate of Ziram 76% WG.

Validity criteria fulfilled:

yes

Conclusions:

The impact of Ziram 76 % WG on soil nitrogen turnover and short term respiration activities can be assessed as negligible even at the 10 × recommended application rate of 40 kg product/ha.

Executive summary:

Materials and methods: The possible effects of Ziram 76 % WG on the soil microflora were measured in a test on nitrogen turnover after addition of lucerne meal and on short term respiration after enrichment with glucose prior to the measurement of respiration. The test was performed in accordance with BBA guideline, part VI, 1-1. Two soil types were used, specified as sandy soil (BBA type 2.3) and a sandy-loam soil.
Ziram 76 % WG was incubated over a period of 28 days (nitrogen turnover) and 56 days (short term respiration) at 1 time and 10 times dosage rates, referring to 4 kg/ha and 40 kg product/ha, respectively.

The control consisted of a treatment group with deionised water. A reference group with Herbogil liquide, a formulation containing 250 g dinoterb/L, was also tested to demonstrate the normal sensitivity of the soil microflora against pesticides.

Results and discussion: Soil type 1: In the treatment groups, the deviation of the content of inorganic nitrogen (expressed as Nmin) was less than 15 % from the control group within 28 days.
The short term respiration of the soil microflora was not significantly different from the control over a 56 day period after admixture with glucose at 1 × and 10 × dosage rates, referring to 4 and 40 kg/ha, respectively.

Soil type 2: The content of Nmin was in the range of the control groups and was not significantly different from the controls. Therefore, the impact on soil nitrogen turnover is considered negligible even at 10 × dosage rate over a 28 day period.
There were no remarkable effects of Ziram 76 % WG on the short term respiration of the soil microflora at 1 × and 10 × dosage rates after admixture with glucose observed over a period of 56 days.

The reference item dinoterb inhibited the short term respiration and stimulated the turnover of inorganic nitrogen within the 56 days and 28 days incubation. The deviation from the control was more than 15 %.

Reference 2

Endpoint:

toxicity to soil microorganisms

Type of information:

experimental study

Adequacy of study:

key study

Study period:

21 Aug - 19 Sep 2013

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)

Version / remarks:

2000

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: OEPP/EPPO Environmental Risk Assessment Scheme for Plant Protection Products. PP 3/7 (2): Chapter 8: Soil Organisms and Functions-Soil microflora. Bulletin OEPP/EPPO Bulletin 33: 200-202

Version / remarks:

2003

Qualifier:

according to guideline

Guideline:

other: SETAC Guideline - Procedures for Assessing the Environmental Fate and Ecotoxicity of Pesticides, Soil Microorganisms, page 40 - 42

Version / remarks:

1995

GLP compliance:

yes (incl. QA statement)

Remarks:

Hess. Ministerium für Umwelt, Energie, Landwirtschaft und Verbraucherschutz, Wiesbaden, Germany

Analytical monitoring:

yes

Details on sampling:

- Concentrations: control, 1.52, 7.6, 15.2, 40.5 mg/kg soil dw
- Sampling method: For the determination of nitrogen content, soil samples were taken within 6 hours after application and afterwards on each sampling date (7, 14 and 28 days). Samples were extracted as described in field "Details on analytical methods".
- Sample storage conditions before analysis: Extracts were stored deep frozen.

Vehicle:

yes

Remarks:

acetone

Details on preparation and application of test substrate:

APPLICATION OF TEST SUBSTANCE TO SOIL
- Type of organic substrate: lucerne meal (0.5%)
- Method: A stock solution was prepared by dissolving 320 mg Ziram technical in 20 mL acetone. Appropriate amounts of the solution were dropped onto quartz sand. After evaporation of the solvent, the quartz sand was mixed to the soil using a laboratory mixer; in the course of the procedure the soil was ventilated and moistened with an adequate amount of deionised water. The soil water contents were adjusted to approximately 51% to 53% of the water holding capacity (WHCmax).

VEHICLE:
- Chemical name of vehicle: acetone
- Concentration of vehicle in test medium: To the control soil, acetone treated quartz sand, a corresponding amount of deionised water and an amount of 0.5% lucerne meal (related to soil dry weight) was added. The soil water content was adjusted to approximately 53% of the water holding capacity (WHCmax).
- Evaporation of vehicle before use: yes

Test organisms (inoculum):

soil

Total exposure duration:

28 d

Test temperature:

20°C ± 2°C

Moisture:

50.2% - 54.4% of maximum water holding capacity

Organic carbon content (% dry weight):

1.25

Details on test conditions:

TEST SYSTEM
- Testing facility: see reference
- Test container: disposable plastic boxes 250 g - 500 g (dry weight), box size approximately 0.5 L, (width/depth/height = 0.1/0.1/0.065 m)
- Amount of soil: boxes filled up to 6 cm
- No. of replicates per concentration: 3
- No. of replicates per control: 3

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographical reference of sampling site: longitude 8° 44' 38.70'' E, latitude 49° 51' 59.59'' N
- History of site: For at least four years prior to test initiation, no pesticides had been used on the soil. No organic or mineral fertilizer had been applied to the soils for at least 4 years prior to study initiation. The field has been rented since 2004 by the laboratory.
- Treatments with pesticides or fertilizers: see history
- Soil texture: silty sand
- % sand: 59.9
- % silt: 33.2
- % clay: 6.9
- pH (in water): 7.1
- Initial nitrate concentration for nitrogen transformation test (mg nitrate/kg dry weight):
- NH4+: 0.204 mg/kg dry weight
- NO2-: 0.101 mg/kg dry weight
- NO3-: 13.669 mg/kg dry weight
- Nmin: 13.974 mg/kg dry weight
- Maximum water holding capacity (in % dry weigth): 38.2
- Cation exchange capacity (mmol/kg): 55.5
- Pretreatment of soil: The soil batch was sampled (according ISO 10381-6, sampling depth 0.05 to 0.2 m), air dried and sieved (mesh 2 mm) at room temperature.
- Storage: The storage before use was maintained at 20 ± 2°C, with appropriate ventilation and the soil was moistened periodically. The soil dry matter prior to test start was approximately 84.6%. The soil was stored in plastic containers with a sufficient
headspace above the soil to allow gas exchange and the moisture was regulated by spraying deionised water on the surface.
- Initial microbial biomass as % of total organic C: 2.13

TEST CONDITIONS
- Light Regime: in the dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
NH4+, NO2- and NO3- were determined in samples of 6 hours after application and afterwards on each sampling date (7, 14 and 28 days).

VEHICLE CONTROL PERFORMED: yes (acetone treated quartz sand mixed into soil)

Nominal and measured concentrations:

Nominal: Control, 1.52, 7.6, 15.2, 40.5 mg/kg soil dw

Reference substance (positive control):

yes

Remarks:

Sodium chloride (16 g/kg dry soil)

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

> 40.5 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

nitrate formation rate

Remarks on result:

other: estimated retrospectively based on results

Details on results:

- Effect concentrations exceeding solubility of substance in test medium: no

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Results with reference item: Cumulative calculation of nitrate formation rates resulted in statistically significant differences between control and sodium chloride treated soil within the test. The deviation from control was clearly higher than 25%. On days 28 and 98, the difference from control was -113.33% and -103.96%, respectively. Therefore the reference item sodium chloride has a significant impact on nitrogen turnover of soil microflora when applied at 16 g/kg soil dry weight. The reference item sodium chloride has long term influence on soil microflora and confirms the sensitivity of the test system.

The differences between the mineral nitrogen content of the control and the four Ziram technical treated soil treatments were also clearly below the 25% trigger value at day 28 (required only by the EPPO and SETAC guidelines). At day 28 the differences were -0.23%, 5.00%, 7.11% and 10.05%, respectively.

The difference in the soil nitrate formation rates between the control and the four test item treatments was below the OECD guideline 216 trigger value of 25% at the 0 to 28 day interval.

Based on the results of this study, it is concluded that Ziram technical had no significant impact on nitrogen transformation when applied at concentrations up to 40.50 mg Ziram technical/kg soil dry weight.

Table 1: Validity criteria for OECD 216 (2000)

Criterion from the guideline	Outcome	Validity criterion fulfilled
The variation of nitrate concentrations between replicate control samples should be less than ± 15%.	Nitrate content: 0.7 – 4.77 Mineral Nitrogen content: 0.63 – 4.42	yes

Validity criteria fulfilled:

yes

Remarks:

For more details refer to field "any other information on results incl. tables"

Description of key information

LC50 (28 d) > 40.5 mg test item/kg soil dw (nominal, OECD 216)

Additional information

Two studies investigating the toxicity of zinc bis dimethyldithiocarbamate (CAS No. 137-30-4) to soil microorganisms are available.

The key study (2013) was performed according to the OECD Guideline No. 216 and GLP. The study was also conducted in accordance with OEPP/EPPO (2003) Environmental Risk Assessment Scheme for Plant Protection Products and SETAC Guideline (1995) - Procedures for Assessing the Environmental Fate and Ecotoxicity of Pesticides, Soil Microorganisms. Nitrogen-transformation in soil enriched with lucerne meal (concentration in soil 0.5%) was followed for 28 d. For this purpose ammonium-, nitrite- and nitrate-nitrogen levels, were measured by ion chromatography and compared with a non-treated soil. Dose rates of 1.52, 7.6, 15.2, and 40.5 mg Ziram technical/kg soil dw were selected. Sodium chloride was used as a reference substance. The difference in the soil nitrate formation rates between the control and the four test item treatments was below the OECD guideline 216 trigger value of 25% at the 0 to 28 day interval. The differences between the mineral nitrogen content of the control and the four Ziram technical treated soil treatments were also clearly below the 25% trigger value at day 28 (required only by the EPPO and SETAC guidelines). Since no inhibition > 50% was recorded in the study the EC50 value was retrospectively estimated to be higher than the highest tested concentration (LC50 (28 d) > 40.5 mg test item/kg soil dw).

One supporting study (1999) conducted according to BBA Guideline, Part VI, 1-1 (1990) and GLP is available. The test substance was Ziram 76 WG and was incubated in two different soil types (sandy and sandy loam) for 56 days at two concentration rates (4 kg/ha (3.04 kg a.i./ha) and 40 kg/ha (30.4 kg a.i./ha)). The results found in the treatment groups regarding nitrogen turnover (measured as inorganic nitrogen content after 28 days) and short-term respiration rates did not differ significantly from those in the controls. Therefore, the impact of this substance on soil microorganisms activity can be considered as negligible (NOEC (56d) ≥ 30.4 kg a.i./ha). The study does not comply with nowadays standards and was therefore used as supporting information.