imidacloprid (ISO); 1-(6-chloropyridin-3-ylmethyl)-N-nitroimidazolidin-2-ylidenamine

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13 Jun to 25 Jun, 1990

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPP 72-2 (Aquatic Invertebrate Acute Toxicity Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

The measured concentrations of the test material in test dilution water were determined at 0- and 48-hours of the toxicity test. Control and the test material fortified samples were also determined at each sampling period.
During the 0-hour sampling, 40 mL aliquots from parent solutions were sampled. At the 48-hour sampling period, 20 ml aliquots from each replicate, for a total of 40 mL were sampled.

Vehicle:

no

Details on test solutions:

The preparation of the test solutions was corrected for the specified purity. This material was used to prepare quality control samples. The highest test concentration (113 mg/L) was sonicated for approximately 20 minutes to break up some precipitate that had formed when adding the compound to the dilution water.

Test organisms (species):

Daphnia magna

Details on test organisms:

The Daphnia magna used in the test were cultured at the ABC facilities. The adult daphnids were fed with a suspension of at least one algae species Selenastrum capricornutum, Ankistrodesmus falcatus and/or Chlamydomonas reinhardtii. Along with the algae, the daphnids were fed with a supplement consisting of trout chow and yeast. The daphnids were fed with this feeding regime at least every three days. The original culture of daphnids at ABC Labs were identified to species using the taxonomic key presented by Pennak. A total of 120 instar from ABC culture were used for definitive bioassay.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

140 mg/L

Test temperature:

20-21°C

pH:

8.3 - 8.4

Dissolved oxygen:

8.0 - 8.4 mg/mL (94 - 97% saturation)

Salinity:

Not applicable

Conductivity:

310 µmhos/cm

Nominal and measured concentrations:

Nominal: 16, 27, 45, 75 and 125 mg/L
Measured: 15, 25, 42, 71 and 113 mg/L

Details on test conditions:

The bioassay was conducted in 250 mL glass beakers containing 200 mL of daphnid culture/test water. The depth and diameter of the test vessels were approximately 9 and 6.5 cm, respectively. The depth and surface diameter of the test solution in the test vessels was approximately 6.3 and 6.5 cm, respectively. All test vessels were covered with loose-fitting petri dish covers to minimize evaporation and prevent contamination during the study. These vessels were kept at 20 ±1.0°C in a temperature controlled water bath with a continuous recording of the water bath temperature maintained during the study. The lighting was maintained at 50-70 footcandles on a 16-hour daylight photoperiod with 30-minute simulated dawn and dusk periods.

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

85 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

mobility

Details on results:

The no-effect concentration based on the absence of immobility and abnormal effects was 42 mg/L since no abnormal effects were observed at or below this concentration after 48 hours. The abnormal effects of immobility, daphnids coated with extraneous material and/or daphnids on the bottom of test chambers were observed in the mean measured concentrations of 71 and 113 mg/L during the study.

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 48-hour EC50 for Daphnia magna was 85 mg/L.

Description of key information

From the acute toxicity study of the test substance on Cloeon dipterum the 48-hours EC50 for aquatic invertebrates was 2.7 µg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

2.7 µg/L

Additional information

In the key study (1990), the acute toxicity of test material to aquatic invertebrates was investigated in a 48-hours static test with the Daphnia magna according to guideline EPA No. 72-2. Ten daphnia per replicate and 2 replicates per test concentration were exposed for 48 hours under static conditions to mean measured concentrations of 15, 25, 42, 71 and 113 mg a.s./L, alongside with a control. The 48-hour EC50 was determined to be 85 mg a.s./L

 

A non-guideline study on acute toxicity of the test substance on Cloeon dipterum is available. The EC50 (48 h) value was determined to be 0.0027 mg/L. This study was considered relevant and reliable for use in classification in accordance with RAC “Opinion proposing harmonised classification and labelling at EU level of imidacloprid”and will therefore be used for the PNEC derivation.