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 soil microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to soil microorganisms

Type of information:

experimental study

Adequacy of study:

key study

Study period:

08 Aug - 05 Sep 1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

BBA Part VI, 1-1

Version / remarks:

1990

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on preparation and application of test substrate:

AMENDMENT OF SOIL
- Type of organic substrate: Natural soils collected on June 15 1995 passed through a 2 mm sieve and stored until used, as described in the BBA Guideline (1990) and ISO/DIS 1036-6 (1992).

APPLICATION OF TEST SUBSTANCE TO SOIL
- Method: treated with either 10 g ground quartz sand/kg dry wt soil (control) or a mixture of quartz sand and the test item (0.26 mg a.i. or 2.57 mg a.i./kg dw soil). The samples were mixed with pulverized lucerne-grass-green meal (5000 mg/kg dw soil) and quartz sand in 4 L aluminium containers by rolling on a gyrowheel mixer for 15 min at 50 rpm.

Test organisms (inoculum):

soil

Total exposure duration:

28 d

Test temperature:

20 ± 2 °C

Moisture:

40 % (Soil 1) and 43.6 % (Soil 2) water capacit

Details on test conditions:

TEST SYSTEM
- Testing facility: laboratory
- Test container (type, material, size): 500 mL brown glass bottles
- Amount of soil: 250 g dw
- No. of replicates per concentration: 1
- No. of replicates per control: 1

SOIL INCUBATION
- Method: series of individual subsamples

SOURCE AND PROPERTIES OF SUBSTRATE (soil 1)
- Organic carbon content (% dry weight): 0.6
- Nitrogen content (% dry weight): 0.06
- Geographical reference of sampling site: from Field plot F on the lab´s experimental farm Laacherhof
- Vegetation cover: Grass was planted in 1987, summer wheat in 1988, winter rye in 1988/89, winter barley in 1989/90, winter wheat in 1990/91, grass in Spring 1991, summer wheat in 1993 and winter rye in 1993/1994.
- Treatments with pesticides or fertilizers: Plant protection chemicals have not been used on this field since 1981.
- Accidental contamination: no
- Particle size distribution (in weight %): 2000-630 µm: 5.0, 630-200 µm: 53.2, 200-63 µm: 17.5, 63-20 µm: 9.3, 20-6.3 µm: 6.6, 6.3-2.0 µm: 4.7, 2.0-0 µm: 3.7
- Soil taxonomic classification: silty sand (according to DIN ‘schluffiger Sand’)
- pH: 5.8
- Initial nitrate concentration for nitrogen transformation test (mg nitrate/kg dry weight): 34.5
- Maximum water holding capacity (in % dry weigth): 40
- Pretreatment of soil: mixed with pulverized lucerne-grass-green meal (5000 mg/kg soil dw)
- Microbial biomass: 187 mg microbial C/kg soil dw

SOURCE AND PROPERTIES OF SUBSTRATE (soil 2)
- Geographical reference of sampling site: from Field plot am Hohenseh 4 a on the lab's experimental farm Höfchen.
- Vegetation cover: 1985/86, summer barley; 1986/87, winter barley; 1987/88, oats; Fall 1988, winter barley ploughed up, perennial ryegrass planted.
- Treatments with pesticides or fertilizers: Plant protection chemicals have not been used on this field since 1988. The last fertilizer was applied in the Fall of 1988.
- Accidental contamination: no
- Particle size distribution (in weight %): 2000-630 µm: 1.8, 630-200 µm: 1.9, 200-63 µm: 3.0, 63-20 µm: 49.7, 20-6.3 µm: 26.7, 6.3-2.0 µm: 10.6, 2.0-0 µm: 6.3
- Soil taxonomic classification: silt (according to DIN ‘Schluff’)
- pH: 7.2
- Initial nitrate concentration for nitrogen transformation test (mg nitrate/kg dry weight): 90.59
- Maximum water holding capacity (in % dry weigth): 43.6
- Microbial biomass: 187 mg microbial C/kg soil dw


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : determination of ammonium (indophenol green reaction), nitrite (samples were treated in acid medium with sulfanilic acid and N-1-naphthylethylenediaminedihydrochloride. The nitrite ions reacted to form a diazo dye, and the extinction of the dye was measured at 540 nm) and nitrates plus nitrite (nitrate ions were reduced to nitrite ions by hydrazine sulfate in the presence of Cu-ll-sulfate in alkaline medium. The nitrite ions were determined as described before)

Nominal and measured concentrations:

Nominal concentrations: 0 (control), 0.26 and 2.57 mg a.i./kg soil dw

Reference substance (positive control):

no

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 2.57 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

nitrate formation rate

Remarks on result:

other:

Remarks:

Soil 1 and soil 2

In the time intervals analysed from 14-28 days exposure the difference in the daily nitrate-N rates does not exceed the trigger value of 25 %.

Table 1: Nitrogen mineralization in Soil 1, a silty sand, 0.6 % org.C, pH (KCI) 5.8, after treatment with the test item and addition of lucerne-grass-green meal (5000 mg/kg dry wt soil)

Days after treatment	Control		0.26 mg a.i./kg soil dw		2.57 mg a.i./kg soil dw
	Ammonium	Nitrate	Ammonium	Nitrate	Ammonium	Nitrate
	[mg Nitrogen/kg soil dw]*
0	2.85 ± 0.19	33.29 ±2.64	2.83 ± 0.30	32.57 ± 1.81	2.60 ± 0.24	32.32 ± 2.60
14	1.78 ± 0.47	14.98 ± 5.98	1.69 ± 0.08	16.62 ± 1.75	1.68 ± 0.14	18.92 ± 4.08
28	0.77 ± 0.05	32.59 ± 4.67	0.79 ± 0.03	30.36 ± 0.94	0.73 ± 0.05	32.63 ± 4.33

*Averages and standard deviations from 3 soil samples

Table 2: Nitrogen mineralization in Soil 2, a silt, 2.3 % org. C, pH (KCI) 7.2, after treatment with the test item and addition of lucerne-grass-green meal (5000 mg/kg drywt soil)

Days after treatment	Control		0.26 mg a.i./kg soil dw		2.57 mg a.i./kg soil dw
	Ammonium	Nitrate	Ammonium	Nitrate	Ammonium	Nitrate
	[mg] Nitrogen/kg soil dw*
0	4.18 ± 0.20	94.43 ± 0.60	4.17 ± 0.07	93.23 ± 1.06	4.14 ± 0.18	95.02 ± 0.81
14	1.64 ± 0.07	103.46 ± 1.53	1.67 ± 0.06	101.85 ± 0.72	1.68 ± 0.01	100.28 ± 2.04
28	1.15 ± 0.06	106.05 ± 4.08	1.15 ± 0.06	104.55 ± 1.51	1.13 ± 0.04	103.44 ± 1.01

*Averages and standard deviations from 3 soil samples

Table 3: Rates of nitrogen transformation/day for silty sand soil 

Time interval (days)	control	0.26 mg/kg		2.57 mg/kg
	mg nitrogen / kg dry weight soil / time interval / day
	nitrate (MV)	nitrate (MV)	% Diff.	nitrate (MV)	% Diff.
0-14	-1,31	-1,14	-12,89	-0,96	-26,82
14-28	1,26	0,98	-21,98	0,98	-22,15

 

Table 4: Rates of nitrogen transformation/day for silt soil 

Time interval (days)	control	0.26 mg/kg		2.57 mg/kg
	mg nitrogen / kg dry weight soil / time interval / day
	nitrate (MV)	nitrate (MV)	% Diff.	nitrate (MV)	% Diff.
0-14	0,64	0,62	-4,54	0,38	-41,75
14-28	0,19	0,19	4,25	0,23	22,01

Table 5: 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%.	CV% < 25% after 28 days	yes

Validity criteria fulfilled:

yes

Remarks:

For further details please refer to “Any other information on results incl. tables”.

Conclusions:

The test item concentrations of 0.26 mg a.i./kg soil dw and the 10-fold overdose (2.57 mg a.i./kg soil dw) did not affect the nitrogen turnover in two different soils during 28-day experiment performed according to BBA Part VI, 1-1.

Reference 2

Endpoint:

toxicity to soil microorganisms

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

BBA Part VI, 1-1

Version / remarks:

1990

GLP compliance:

yes (incl. QA statement)

Vehicle:

yes

Remarks:

quartz sand

Details on preparation and application of test substrate:

Sieved soil was treated with either 10 g ground quartz sand/kg dry wt soil (control) or a mixture of quartz sand and the test substance (0.26 mg or 2.57 mg test substance/kg dry wt soil). The samples were mixed in 4 liter aluminium containers by rolling on a gyrowheel mixer (Elte 650, J. Engelsmann AG, Ludwigshafen, Germany) for 15 min at 50 rpm.

Test organisms (inoculum):

soil

Total exposure duration:

28 d

Nominal and measured concentrations:

Nominal: 187.5 g and 1875 g test substance/ha corresponded to 0.26 mg and 2.57 mg test substance/kg dry wt soil

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

0.26 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

respiration rate

Remarks on result:

other:

Remarks:

Silty sand soil

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

2.75 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

respiration rate

Remarks on result:

other:

Remarks:

Silt soil

Validity criteria fulfilled:

not specified

Conclusions:

During 28-day experiments, 187.5 g a.i./ha (equivalent to 0.26 mg a.i./kg dry wt soil) and 1875 g a.i/ha (equivalent to 2.57 mg a.i. /kg dry wt soil) had no influence on soil respiration after addition of glucose to a silty sand (0.6 % org. C, pH (KCI) 5.7) or a silt (2.3 % org. C, pH (KCI) 7.1).

Description of key information

NOEC (28 d): ≥ 2.57 mg/kg soil dw (nominal, soil microflora, BBA Part VI, 1-1)

Additional information

Two studies are available assessing the effects of 3-(2-chlor-5-pyridyl-methyl)-cyanimino-1,3-thiazolidin on soil microorganisms according to BBA Part VI, 1-1.

In the first study, 2 lucerne-grass-green-meal amended soils (5000 mg/kg) were treated with 187.5 g test item/ha (corresponding to 0.26 mg a.i./kg soil dw) and the 10-fold overdose of the test item (1875 g a.i./ha, corresponding to 2.57 mg a.i./kg soil dw). Immediately after treatment and after 14 and 28 days, the soils were analyzed for their content of ammonium-N, nitrite-N and nitrate-N plus nitrite-N. The analyzes revealed that the test item treatment had no influence on the turnover of nitrogen in both soils (NOEC (28 d) ≥ 2.57 mg a.i./kg soil dw).

The second study supports the results of the key study. The test substance (0.26 mg or 2.57 mg test substance/kg dry wt soil) showed no influence on soil respiration after addition of glucose to two soils during 28 days of incubation (NOEC (28 d) ≥ 2.57 mg a.i./kg soil dw).