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 algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

effects on growth of green algae

Type of information:

experimental study

Adequacy of study:

key study

Study period:

08 - 13 May 1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

1984

Deviations:

yes

Remarks:

Age of pre-culture: 5 days, initial cell densitiy was 3000 cells/mL instead of 5 x 10^3-10^4 cells/mL, analyses of the test item were made cell-free samples of the nutrient medium. These deviations have no impact on the outcome of the study.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0 (conrtol), 3.20, 5.60,10.0,18.0, 32.0, 56.0 und 100 mg/L (in cell-free samples of the nutrient medium)
- Sampling method: Samples were taken at the begining and at the end of the test.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Stock solutions was prepared by adding 56.3 mg of the test item to a 1000 mL flask and mixed with sterile, deionized water. The stock solution was used to prepare cultures treated with 3.20 to 5.60 mg test item/L. Before use, the stock solution was ultrasonicated for 10 minutes and stirred for 40 minutes. For cultures treated with 10.0 to 56.0 mg test item/L, the appropriate quantities of test item needed were weighed out, added directly to the nutrient medium, which was also ultrasonicated and stirred.
- Differential loading: no
- Controls: dilution water only
- Test concentration separation factor: 1.75 - 1.8

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Strain: 61.81
- Source: laboratory culture
- Age of inoculum (at test initiation): 5 days
- Method of cultivation: Cultured under 23 ± 2 °C under 16 h light/day in cotton plugged, 300-mL Erlenmeyer flasks containing 50 mL of nutrient solution number 1 (Bringmann and Kuhn, 1980). Fresh stock cultures were prepared once a week. All operations were conducted under sterile conditions.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

120 h

Test temperature:

23 ± 2 °C

pH:

7.87 - 9.87

Nominal and measured concentrations:

Nominal concentrations: 0 (control), 3.20, 5.60,10.0,18.0, 32.0, 56.0 und 100 mg/L
Mean measured concentrations: < LOQ, 2.98, 5.25, 9.44, 16.8, 30.1, 52.8 and 184.4 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 300 mL Erlenmeyer flasks
- Type (delete if not applicable): closed (sealed with cotton wool plugs)
- Material, headspace, fill volume: glass, 150 mL, 150 mL
- Aeration: no
- Initial cells density: 3000 cells/mL
- Control end cells density: 82.17 (72 h), 293 (96 h), 522 (120 h)
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes (OECD TG 201 medium)

TEST MEDIUM / WATER PARAMETERS
- Culture medium different from test medium: yes
- Intervals of water quality measurement: pH and temperature (daily)

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: continuous fluorescent light
- Light intensity and quality: 8000 lux ± 20 %

EFFECT PARAMETERS MEASURED: Cell numbers were determined daily and microscopically at a magnification of 400 times using a Thoma counting chamber.

Reference substance (positive control):

yes

Remarks:

K2Cr2O7

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Results with reference substance (positive control):

ErC50 (72 h) = 0.81 mg/L (The guideline OECD 201 does not recommend an appropriate range for the EC50. However, the guideline ISO 8692 (2004) recommends an EC50 around 1.19 mg potassium dichromate /L which is comparable to the value found in this reference test.)

Reported statistics and error estimates:

The NOEC and LOEC were calculated by an analysis of variance ("Dunnett's-Test").

Table 1: Mean cell numbers in the test 

Nominal concentration [mg/L]	Cell numbers (× 10^4/mL)
	0 h	24 h	48 h	72 h	96 h	120 h
Control	0.3	1.75	13.42	82.17	293	522
3.2	0.3	1.67	11.17	79	278	504
5.60	0.3	1.50	11	83	263.33	526.67
10	0.3	0.67	12	81	282.67	509
18	0.3	1.50	13.67	100	242	505
32	0.3	1	10	91.5	218.67	446.67
56	0.3	0.50	7.67	41.67	156.33	349.33
100	0.3	0.17	2.00	6.33	33	123.5

Table 2: Analytical results in the test

Nominal conc. [a.i./L]	Sample time [days]	Measured concentrations of thiacloprid
		1. measurement [mg a.i./L]	2. measurement [mg a.i./L]	Average (rounded) [mg a.i./L]
Control	0	< 0.05	< 0.05	< 0.05
	5	< 0.05	< 0.05	< 0.05
3.1	0	3.005	2.972	2.99
	5	2.982	2.943	2.96
5.42	0	5.308	5.248	5.28
	5	5.200	5.220	5.21
9.68	0	9.356	9.435	9.40
	5	9.478	9.478	9.48
17.4	0	16.66	16.92	16.8
	5	16.62	16.70	16.7
31	0	30.26	30.41	30.3
	5	29.78	29.93	29.9
54.2	0	53.41	53.28	53.3
	5	52.13	52.33	52.2
96.8	0	92.09	91.69	91.9
	5	92.31	92.64	92.5

Table 3: Validity criteria for OECD 201 (2006)

Criterion from the guideline	Outcome	Validity criterion fulfilled
The biomass in the control cultures should have increased exponentially by a factor of at least 16 within the 72-hour test period.	273 (72 h)	yes
The mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3, for 72-hour tests) in the control cultures must not exceed 35%	20.9 (72 h)	yes
The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures must not exceed 7% in tests with Pseudokirchneriella subcapitata. For other less frequently tested species, the value should not exceed 10%.	2.09 (72 h)	yes

Validity criteria fulfilled:

yes

Remarks:

For further, details, please refer to 'Any other information on results incl. tables'.

Conclusions:

The ErC50 (72 h) for Pseudokirchneriella subcapitata exposed to thiacloprid is > 100 mg/L (nominal). The NOErC was determined to be 32 mg/L (nominal).

Reference 2

Endpoint:

effects on growth of green algae

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

26 - 29 Jun 1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

1984

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

no

Test organisms (species):

other: Scenedesmus subspicatus

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Nominal and measured concentrations:

Nominal concentrations: 0 (control), 10, 18, 32, 56, 100 and 180 mg/L
Mean measured concentrations: < LOQ (control), 11.0, 16.8, 29.7, 52.5, 91.8 and 149 mg/L

Details on test conditions:

- Initial cells density: 1 x 10^4 cells/mL

Reference substance (positive control):

yes

Remarks:

K2Cr2O7

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

96.7 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Validity criteria fulfilled:

yes

Conclusions:

The ErC50 (72 h) for Scenedesmus subspicatus exposed to the test item is 96.7 mg/L (nominal). The NOErC was determined to be 32 mg/L (nominal).

Description of key information

NOErC (72 h) = 32 mg/L (nominal, Pseudokirchneriella subcapitata, OECD 201)

ErC50 (72 h) > 100 mg/L (nominal, Pseudokirchneriella subcapitata, OECD 201)

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L

EC10 or NOEC for freshwater algae:

32 mg/L

Additional information

Two GLP studies assessing the toxicity of the test item on green algae are available. Both studies were performed under static conditions according to OECD 201.

The key study was performed with Pseudokirchneriella subcapitata which was exposed to nominal test item concentrations ranging from 3.2 to 100 mg/L for 120 h. Mean measured concentrations measured in separate cell-free replicates were between 94.7 and 98.5 % of nominal concentrations. The derived ErC50 (72 h) for growth rate was determined to be > 100 mg/L (nominal) and the NOErC (72 h) was 32 mg/L (nominal).

This result is supported by a further study with green algae Scenedesmus subspicatus. The influence of the test item on growth of shake cultures of the green alga, Scenedesmus subspicatus, was determined in a 72 h experiment with nominal concentrations in the range of 10 and 180 mg test item/L. Mean measured concentrations in separate cell-free replicates were between 11 and 149 mg/L. The derived ErC50 (72) was determined to be 96.7 mg/L (nominal) and the NOErC was 32 mg/L.