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 microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

03 - 05 Jul 1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: waste treatment plant Odenthal, Germany
- Method of cultivation: not reported
- Preparation of inoculum for exposure:
- Pretreatment: none
- Initial biomass concentration: 800 mg/L

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

30 min

Test temperature:

20 ± 2 °C

pH:

8.0

Nominal and measured concentrations:

Nominal concentrations: 1000, 1800, 3200, 5600 and 10000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: not reported
- Material, size, headspace, fill volume: not reported
- Aeration: yes
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2
- No. of vessels per abiotic control (replicates): 1 (10000 mg/L)
- Sludge concentration: 800 mg/L
- Nutrients provided for bacteria: not reported
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: synthetic medium
OTHER TEST CONDITIONS
- Adjustment of pH: no

EFFECT PARAMETERS MEASURED: respiratory rate after 3 hours

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

6 330 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

The abiotic O2-consumption was determined at a concentration of the test substance of 10000 mg/L. As no abiotic O2-consumption was determined at this concentration, also lower concentrations of the test substance do not cause O2-consumption.

Results with reference substance (positive control):

- Results with reference substance valid? yes (EC50 (30 min) of 3,5-DCP should be in the range 2 – 25 mg/L
- Relevant effect levels: EC50 (30 min) = 14 mg/L

Table 1: Results on respiratory rate in the test after 3 hours

Nominal Concentration [mg/L]	Respiratory rate [mg/L*h]	Abiotic O2consumption [mg/L*h]	Respiratory abiotic O2consumption [mg/L*h]	Inhibition [%]
1000	50.0	0.0*	50.0	16.7
1800	52.0	0.0*	52.0	13.3
3200	50.0	0.0*	50.0	16.7
5600	46.0	0.0*	46.0	23.3
10000	7.3	0.0	7.3	87.8
Control	60.0

* No abiotic O₂consumption was determined at the highest test concentration. Lower concentrations of the test substance do not cause O₂consumption either (postulated values).

Table 2: Validity criteria for OECD 209

Criterion from the guideline	Outcome	Validity criterion fulfilled
The blank controls (without the test substance or reference substance) oxygen uptake rate should not be less than 20 mg oxygen per one gram of activated sludge (dry weight of suspended solids) in an hour.	75 mg O2/g	yes
The coefficient of variation of oxygen uptake rate in control replicates should not be more than 30% at the end of definitive test.	0%	yes

Validity criteria fulfilled:

yes

Conclusions:

The EC50 (30 min) of the test item towards activated sludge was 6330 mg/L (nominal) based on total respiration inhibtion.

Description of key information

EC50 (30 min) = 6330 mg/L (nominal, activated sludge, ISO 8192)

Key value for chemical safety assessment

EC50 for microorganisms:

6 330 mg/L

Additional information

One study is available assessing the effects of the test item on microorganisms according to ISO 8192. In this key study, 800 mg/L of activated sludge (mixed population of different microorganisms) was treated with synthetic medium for 30 minutes and the respiratory rate was measured. This respiratory rate was compared with those measured in test batches containing different concentrations of the test substance (1000 - 10000 mg/L). The sensitivity of the activated sludge being used was checked with 3,5-dichlorphenol as reference substance. The EC50 (30 minutes) was determined to be 6330 mg/L (nominal). For the reference substance 3,5-dichlorphenol an EC50 (30 min) value of 14 mg/L (nominal) was determined.