clothianidin (ISO); (E)-1-(2-chloro-1,3-thiazol-5-ylmethyl)-3-methyl-2-nitroguanidine

Toxicity to terrestrial plants

Link to relevant study record(s)

Reference

Endpoint:

toxicity to terrestrial plants: long-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12 Oct - 30 Nov, 1999

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.4100 (Terrestrial Plant Toxicity Tier I (seedling emergence))

Version / remarks:

1996

Deviations:

not specified

Remarks:

Deviations according to the current guideline OECD 208: few toxicity symptoms are observed in the control, evaluation done after 14 days after spraying (not 14 days after 50% of seedling emergence), the number of seed per pot is high.

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Analytical samples were collected immediately after spray mixtures were prepared. After thorough mixing triplicate samples were collected from the 225 g a.i./ha treatment group spray mixture. Single samples were collected from the formulation blank and the negative control
spray mixtures. Samples were transferred upon their collection to the Analytical Laboratory for analysis.

Vehicle:

no

Details on preparation and application of test substrate:

The spray mixture for the test concentration was prepared by diluting 0.4875 g of the test substance to a volume of 1000 mL with water purified by reverse osmosis and mixing by swirling and inversion. The physical appearance of the mixture was a tan, cloudy liquid with a foam layer. The spray mixture was then packaged in an amber glass bottle to prevent further exposure of the mixture to light.
Spray mixtures were applied at a rate of 940 L/ha with a pressurized spray applicator system. Applications were made to the control first, followed by the formulation blank, and lastly the 225 g a.i./ha treatment group in order to avoid cross-contamination.

Species:

Raphanus sativus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Source: Meyer Seed Co. Baltimore, MD
Family: Cruciferae

Species:

Lycopersicon esculentum

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Source: Meyer Seed Co. Baltimore, MD
Family: Solanaceae

Species:

Glycine max (G. soja)

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Source: Johnny's Selected Seeds Albion, ME
Family: Leguminosae

Species:

Brassica oleracea var. capitata

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Source: Meyer Seed Company Baltimore, MD
Family: Cruciferae

Species:

Lactuca sativa

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Source: Territorial Seed Co. Cottage Grove, OR
Family: Compositae

Species:

Phaseolus vulgaris

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Source: Meyer Seed Co. Baltimore, MD
Family: Leguminosae

Species:

Triticum aestivum

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

Source: Arrowhead Mills Inc. Hereford, TX
Family: Gramineae

Species:

Zea mays

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

Source: Johnny's Selected Seeds Albion, ME
Family: Gramineae

Species:

Lolium perenne

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

Source: Meyer Seed Co. Baltimore, MD
Family: Gramineae

Species:

Allium cepa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

Source: Territorial Seed Co. Cottage Grove, OR
Family: Liliaceae

Test type:

seedling emergence and seedling growth test

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

yes

Total exposure duration:

14 d

Remarks:

Duration of the study is based on the application day and not on the 50% emergence day.

Test temperature:

73 to 83°F (22.7 to 28.4°C)

pH:

7.8

Moisture:

21 to 89% of humidity

Details on test conditions:

The replicate pots were placed in a randomized block design on a greenhouse table after spray mixtures were applied.
Seeds used in this study were not treated with fungicides, insecticides or repellents prior to test initiation. Seeds were impartially assigned to pre-labeled growth pots on the day of test initiation.
Seeds were planted in plastic pots (approximately 16 cm in diameter and 11 cm deep) on the day of test substance application. A total of ten seeds in each pot and four replicates per treatment group.

The well water and soil used for plant studies were periodically screened for pesticides and metals. No analytes were measured at levels that were expected to have an impact on the study.
Natural sunlight was not supplemented with artificial lighting during the test. The photoperiod was determined by counting the number of hours with light intensity readings greater than 0.001 kW/m2/sec.
Seedlings were subirrigated.

The soil was determined to consist of 91% sand, 2% silt, and 7% clay, with an organic matter content of 2.4%.

Nominal and measured concentrations:

Nominal: 240 mg a.s./L
Mean measured: 228 mg a.s./L

Reference substance (positive control):

not specified

Key result

Species:

other: for the ten species

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

225 g/ha

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

seedling emergence

Remarks on result:

other: Equivalent to 0.3 mg a.s/kg dws

Details on results:

There were no observed treatment-related effects on any of the test species. The OPPTS 850.4100 guideline states that if less than a 25% detrimental effect or response is noted for a seedling emergence test, no additional testing is ordinarily required. In this study the greatest difference was seen in tomato where there was a 22% reduction in emergence compared to the pooled control. Therefore, the application of 225 g a.i. TI-435 50% WDG/ha and the application of its formulation blank were determined to be a no-observed effect concentration (NOEC) for emergence and growth of all ten species tested.

Please refer to "overall remark/ attached background material" field for result tables.

Validity criteria fulfilled:

not specified

Conclusions:

The present guideline study was conducted in compliance with GLP. Under the test conditions used, the overall NOEC for seedling emergence for the ten species was 225 g a.s./ha (equivalent to 0.3 mg a.s./ kg dws)

Description of key information

The overall NOEC was 225 g a.s./ha (the highest tested rate) equivalent to 0.3 mg a.s./kg dws for both seedling emergence and vegetative vigour studies.

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for terrestrial plants:

0.3 mg/kg soil dw

Additional information

Two GLP-studies are available for toxicity testing to terrestrial plants and one of them was identified as key study.

 

In the key study (2000), the toxicity of test substance sprayed to terrestrial plants was investigated in a 14-day test on seedling emergence according to US EPA OPPTS 850.4100 guideline. Ten species (4 monocotyledonous and 6 dicotyledonous) were exposed to nominal concentration of 225 g a.s./ha (equivalent to 0.3 mg a.s./kg dry soil), alongside with a control. No effect exceeding 25% (22% max compared to controls in tomato) or no significant adverse effects were observed after 14 days exposure for survival and shoot height and dry weight.

 

In the supportive study (2000), the toxicity of substance sprayed sprayed to terrestrial plants was investigated in a 14-day test on vegetative vigor according to US EPA OPPTS 850.4150 guideline. No effect exceeding 25% (9% max compared to controls) were observed after 14 days exposure for survival and shoot height and dry weight.

 

Long-term toxicity testing is not deemed necessary considering the lack of effects in short-term toxicity studies with plants over 21 days.