thiacloprid (ISO);(Z)-3-(6-chloro-3-pyridylmethyl)-1,3-thiazolidin-2-ylidenecyanamide;{(2Z)-3-[(6-chloropyridin-3-yl)methyl]-1,3-thiazolidin-2-ylidene}cyanamide

Toxicity to aquatic plants other than algae

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic plants other than algae

Type of information:

experimental study

Adequacy of study:

key study

Study period:

18 Oct - 02 Nov 1995

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: U.S. EPA-FIFRA PesticideAssessment Guideline § 123-2 Tier 2 "Non-target AquaticPlant Toxicity"

Deviations:

yes

Remarks:

Deviation to OECD 221: Different growth medium used, test duration was 15 d instead of 14 d, no measurement of another another parameter (total frond area, dry weight or fresh weight) besides frond number, no assessment based on specific growth rate made

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0 (control), 3.03, 6.05, 12.1, 24.2, 48.4 and 96.8 mg a.i./L
- Sampling method: Samples were taken at day 0 and 15

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Test concentrations were prepared by adding aliquots of the stock solution (1000 mg test item/L) to a total of 1000 ml test medium.
- Controls: control: dilution water only, solvent control: 1 mL DMF/L
- Chemical name of vehiclle: dimethylformamide
- Concentration of vehicle in test medium: stock solution: 100%, final test solutions: max. 1 mL/L, control: 0%, solvent control: 1 mL/L
- Test concentration separation factor: 2

Test organisms (species):

Lemna gibba

Details on test organisms:

TEST ORGANISM
- Common name: gibbous duckweed
- Strain: G3
- Source: laboratory stock culture (originally obtained from Dr. Janet Slovin, Horticulture Crops Quality Laboratory,U.S. Department of Agriculture, Beltsville, USA)
- Age of inoculum: < 14 days
- Method of cultivation: maintained under sterile conditions in glass dishes filled with Hoagland E medium without Sucrose, Yeast extract, Bactotryptone and EDTA under illumination of 5000 lux ± 15% and temperature of 25 ± 2°C. Transfers are made regularly into fresh mediumto provide less than 14-day old cultures for toxicity test inoculations.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

15 d

Test temperature:

23.7 - 24.2 °C

pH:

4.6 - 6.1

Nominal and measured concentrations:

Nominal concentrations: 0 (control), 3.03, 6.05, 12.1, 24.2, 48.4 and 96.8 mg a.i./L
Mean measured concentrations: < LOD (control), 2.98, 6.05, 12.3, 25.7, 46.8 and 95.4 mg a.i./L

Details on test conditions:

TEST SYSTEM
- Incubation chamber used: yes
- Test vessel: 400 mL glass dishes
- Type: covered with lits of glass to permit gas exchange and illumination
- Material, size, headspace, fill volume: glass, 10 cm diameter x 6 cm height,
- Type of cover: lits of glass
- Aeration: no
- Control end frond number: 189 (solvent control), 235 (control)
- No. of colonies per vessel: 5
- No. of fronds per colony: 3
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3
- No. of vessels per vehicle control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes (M-Hoagland's Medium, ASTM E 1415 -91 (modified: without EDTA, Sucrose, Yeast extract or Bactotryptone)

TEST MEDIUM / WATER PARAMETERS
- Culture medium different from test medium: no
- Intervals of water quality measurement: pH (test start and end) and temperature (daily)

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: continuous light
- Light intensity and quality: 5124 lux (mean of a total of 5 measurements)

EFFECT PARAMETERS MEASURED:
- Determination of frond number: manual counting (day 2, 5, 7, 9, 12 and 15)
- Determination of biomass: no
- Shoot length: no
- Shoot weight (fresh / dry): no
- Determination of frond area: no

Reference substance (positive control):

no

Duration:

15 d

Dose descriptor:

NOEC

Effect conc.:

46.8 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

frond number

Duration:

15 d

Dose descriptor:

EC50

Effect conc.:

141.8 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

frond number

Reported statistics and error estimates:

Data which did not fit a normal distribution were analyzed by the non-parametric Kruskal-Wallis' test and Dunn's Multiple Comparison test to determine if there was a significant difference between the control and treatment groups. Control data were pooled if the t-test criteria was met. If the data was not poolable, only the
corresponding solvent control data was used for further analyses.
This growth data, without previous data transformation were analyzed according to the following statistical methods: the Dunnett's test,the Bonferroni's t-test, the Tukey's test and the Williams' test.

Table 1: Measured concentrations in experimental study

Nominal concentration [mg a.i./L]	Measured concentrations in mg a.i./L
	Day 0	Day 15	Mean
Control	< 0.1	< 0.1<	-
Solvent control	< 0.1	< 0.1<	-
3.03	3.03	2.94	2.98
6.05	6.02	6.07	6.05
12.1	12.3	12.3	12.3
24.2	25.8	25.6	25.7
48.4	46.1	47.6	46.8
96.8	92.0	98.7	95.4

Table 2: Frond counts during test

Mean measured concentration (mg a.i/L)	Replicate	Day 0	Day 12	Day 15
Control	A	15	130	199
	B	15	136	231
	C	15	162	274
	Mean	15	143	235
Solvent control	A	15	115	178
	B	15	128	189
	C	15	126	201
	Mean	15	123	189
2.98	A	15	117	237
	B	15	126	201
	C	15	112	208
	Mean	15	118	215
6.05	A	15	140	238
	B	15	151	244
	C	15	157	267
	Mean	15	149	250
12.3	A	15	138	219
	B	15	147	242
	C	15	148	217
	Mean	15	144	226
25.7	A	15	144	218
	B	15	118	188
	C	15	132	213
	Mean	15	131	206
46.8	A	15	108	156
	B	15	113	186
	C	15	141	225
	Mean	15	121	189
95.4	A	15	82	115
	B	15	104	157
	C	15	119	162
	Mean	15	102	145*

*Denotes statistically significant difference from pooled controls (α = 0.05) at day 15.

Table 3: Validity criteria for OECD 221 (2006)

Criterion from the guideline	Outcome	Validity criterion fulfilled
The doubling time of frond number in the control must be less than 2.5 days (60 h), corresponding to approximately a seven-fold increase in seven days and an average specific growth rate of 0.275 d^-1.	Not determinable since growth rate is not determined.	Not applicable

Validity criteria fulfilled:

not applicable

Conclusions:

The EC50 (15 d) for Lemna gibba exposed to the test item is 141.8 mg a.i./L (mean measured). The NOEC was determined to be 46.8 mg a.i./L (mean measured). Both values refer to frond number inhibition.

Description of key information

NOEC (15 d) = 46.8 mg a.i./L (frond number, mean measured, Lemna gibba, EPA-FIFRA Pesticide Assessment Guideline 123-2 Tier 2)

EC50 (15 d) = 141.8 mg a.i./L (frond number, mean measured, Lemna gibba, EPA-FIFRA Pesticide Assessment Guideline 123-2 Tier 2)

Key value for chemical safety assessment

EC50 for freshwater plants:

141.8 mg/L

EC10 or NOEC for freshwater plants:

46.8 mg/L

Additional information

A 15-day toxicity test is available assessing the toxicity of the test item to Lemna gibba G3, a species of duckweed according to EPA-FIFRA Pesticide Assessment Guideline 123-2 Tier 2. Duckweed plants were exposed under static conditions to six concentrations in the range between 2.98 and 95.4 mg a.i./L. Measured concentrations were between 95 % and 107 % of nominal concentrations. The statistical analyses indicate that the frond count values in the highest tested concentration 95.4 mg a.i./L on day 15, was significantly different from those in the controls.The NOEC (15 d) and EC50 (15 d) were determined to be 46.8 and 141.8 mg a.i./L (mean measured), respectively, based on the number of counted fronds.