clothianidin (ISO); (E)-1-(2-chloro-1,3-thiazol-5-ylmethyl)-3-methyl-2-nitroguanidine

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

fish early-life stage toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

06 Oct - 10 Nov, 2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1400 (Fish Early-life Stage Toxicity Test)

Version / remarks:

1996

Deviations:

not specified

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Prior to test initiation, samples of water were collected from one replicate test chamber of each treatment and control group to evaluate diluter performance. On Days 0, 4, 7, 14, 21, 28 and at test termination, water samples were collected from one alternating replicate test chamber of each treatment and control group and analyzed as soon as possible (without storage) to measure concentrations of the test substance. Water samples were collected at mid-depth from each test chamber and placed in glass scintillation vials.

Vehicle:

yes

Remarks:

DMF

Details on test solutions:

One stock solution was prepared for each of the 5 concentrations tested. A primary stock was prepared by dissolving the test substance in dimethylformamide (DMF) at a concentration of 200 mg a.i./mL. Based on preliminary solubility trials, 200 mg a.i./mL appeared to be the limit of solubility for the test material in DMF. The primary stock solution was inverted and sonicated to aid in the solubilization of the test substance. Aliquots of the primary stock solution were proportionally diluted with DMF to prepare four additional secondary stocks at concentrations of 100, 50, 25 and 12.5 mg a.i./mL. Stock solutions were prepared twice during the definitive test. The five stocks were injected into the diluter mixing chambers (at a rate of 0.0125 mL/minute) where they were mixed with dilution water (at a rate of 125 mL/minute) to achieve the desired test concentrations. The resultant test concentrations were adjusted for the purity of the active ingredient in the test substance (97.6%). The mixing chambers and test solutions appeared clear and colorless at test initiation and test termination.
The solvent control was prepared by injecting DMF into the mixing chamber assigned to the solvent control. The concentration of DMF in the solvent control and all Tl-435 treatment groups was 0.1 mL/L.

Test organisms (species):

Pimephales promelas

Details on test organisms:

Fathead minnow embryos used in this test originated from cultures maintained by laboratory. The embryos were removed from spawning substrates and examined under a dissecting microscope to select healthy viable specimens at approximately the same stage of development. Embryos collected for use in the test were from 10 individual spawns and were less than 24 hours old when the test was initiated.
Newly-hatched larvae were fed live brine shrimp nauplii (Artemia sp.) two to three times per day during the test. Fish were not fed for at least 48 hours prior to the termination of the test to allow for clearance of the digestive tracts before weight measurements were made.

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

33 d

Hardness:

128 - 140 mg/L CaCO3

Test temperature:

23.5 - 25.5 °C

pH:

7.9 - 8.2

Dissolved oxygen:

6.0 - 8.2 mg/L

Salinity:

Not applicable

Conductivity:

345 - 375 µmhos/cm

Nominal and measured concentrations:

Nominal: 1.3, 2.5, 5.0, 10 and 20 mg a.i./L
Mean measured: 1.2, 2.5, 5.5, 9.7 and 20 mg a.i./L
It was not practical to test the test substance at concentrations greater than 20 mg a.i./L due to the solubility in the carrier solvent (DMF) and the solvent concentrations recommended by the testing guidelines.

Details on test conditions:

A continuous-flow diluter was used to deliver each concentration of the test substance, a solvent control and a negative (well water) control.
The test chambers were 9 L glass aquaria filled with approximately 7 L of test solution. The depth of the test water in a representative test chamber was approximately 17 cm. The test chambers were impartially positioned in a temperature-controlled environmental chamber designed to maintain a temperature of 25 ± 1 °C.
Lighting used to illuminate the cultures and test chambers during culturing and testing was provided by fluorescent tubes that emitted wavelengths similar to natural sunlight. A photoperiod of 16 hours of light and 8 hours of dark was controlled with an automatic timer. A 30-minute transition period of low light intensity was provided when lights went on and off to avoid sudden changes in lighting. Light intensity at test initiation was 504 lux at the surface of the water over the negative control.
Temperature was measured in each test chamber at the beginning and end of the test and at weekly intervals during the test. Temperature also was measured continuously in one negative control replicate.

Reference substance (positive control):

not specified

Key result

Duration:

33 d

Dose descriptor:

NOEC

Effect conc.:

>= 20 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

other: hatching success, larval survival, total length, wet weight or dry weight

Details on results:

On Day 4 of the test, it was observed that no embryos were present in replicate C of the 20 mg a.i./L treatment group; only one larval fish was found in the test chamber (not in the embryo incubation cup where it should have been). On Day 3 of the test, all embryos were transferred to new embryo incubation cups and the test chambers were cleaned. It appeared that as the test chambers refilled, the height of the test solution must have risen above the top of the embryo incubation cup, releasing the newly hatched larvae into the test chamber. It is assumed that the larvae subsequently escaped out the aquarium drain (Note: prior to hatch, there are no screens on the aquarium drains.). Consequently, all potential data from replicate C of the 20 mg a.i./L treatment group was lost.

There were no apparent differences among the experimental groups in the time required to hatch.
In general, the majority of all fish appeared normal throughout the test. The most prevalent adverse sublethal observation was the presence of a curved spine. However, this condition was considered to be inherent in the population of organisms used in the test and was not considered to be treatment-related.
The Bonferroni t-test shows no significant reductions in total length, wet weight or dry weight in comparison to the pooled controls.

Please refer to "overall remark/ attached background material" field for result tables.

Validity criteria fulfilled:

not specified

Remarks:

According to OECD 210 criteria, the validity criteria are fullfiled.

Conclusions:

The present guideline study was conducted in compliance with GLP. Under the test conditions used, the overall NOEC (33-day) for early life stage of Pimephales promelas was ≥ 20 mg a.s./L, the highest concentration tested.

Description of key information

The overall NOEC for the early life stages of P. promelas is higher than 20 mg a.s./L.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

NOEC

Effect concentration:

>= 20 mg/L

Additional information

In the key study the long-term effects of the substance towards fish were examined in early-life stage toxicity test with P. promelas under flow-through conditions (2000). The study was carried out according to GLP and OPPTS 850.1790 guidelines. Fish were exposed to mean measured concentrations of 1.2, 2.5, 5.5, 9.7 and 20 mg a.s./L, alongside with a control and a solvent control. Based on mean measured concentrations of the test substance a NOEC≥20 mg a.s./L was determined.