spirodiclofen (ISO);3-(2,4-dichlorophenyl)-2-oxo-1-oxaspiro[4.5]dec-3-en-4-yl 2,2-dimethylbutyrate

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

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

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

1984, Part 1

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

The 48-hr acute toxicity of spirodiclofen technical to Daphnia magna was studied under flowthrough
conditions. The animals in the definitive test were exposed to a dilution water control and the nominal concentrations of 5.6, 10, 18, 32, and 56 µg/L.

Daily observations were for mortality, immobility, and others behavioral sublethal effects. Immobility was equivalent to mortality in this study.

Vehicle:

yes

Details on test solutions:

Method: Flow through conditions. 12 volume turnovers per day. Diluter system delivered fresh test solutions once every two hours.
Source of dilution water: “M7 medium” was used as the dilution water for testing and breeding of the daphnids.
Stock solutions: Day 0 ranged from 90 to 113% on nominal. Day 2 ranged from 104 to 132% of nominal. The variation in any on test level from Day 0 to Day 2 was within acceptable limits (< 1.5) and met the requirements for consistent exposure concentrations (factor of 1.0 - 1.2) Test solutions: Only the three highest test solutions and the controls were analyzed. Since there was no significant mortality at any treatment level, the study director decided to eliminate analysis on the 5.6 and 10 µg/L levels. The Day 0, Day 1 and Day 2 analyses indicated consistent, stable exposure concentrations. The mean measured concentrations for the 18, 32 and 56 µg/L nominal levels were 15.8, 30.7 and 50.8 µg/L, respectively.
Solvent: acidified methanol at 0.1 mL/L. Methanol with 1 volume-percent glacial acetic acid. The methanol was acidified to improve the stability of the stock solution. The solvent did not influence
the test solution pH or the health of the daphnids.

Test organisms (species):

Daphnia magna

Details on test organisms:

Age at test initiation: Less than 24 hours old
Source: In house culture
The animals used for testing were maintained under static renewal test conditions and
fed with green alga (S. subspicatus) or an aqueous Tetramin suspension. The culture conditions and test conditions were the same in temperature, lighting, water and light intensity. No details given on health of the subculture. The test organisms were not fed during the study.

Test type:

static

Water media type:

freshwater

Total exposure duration:

48 h

Hardness:

hardness = 196 mg/L as CaCO3

Test temperature:

temperature = 19.8°C

pH:

pH = 7.7 - 7.8

Nominal and measured concentrations:

Nominal: Stock solutions: Day 0 ranged from 90 to 113% on nominal. Day 2 ranged from 104 to
132% of nominal. The variation in any on test level from Day 0 to Day 2 was within acceptable limits (< 1.5) and met the requirements for consistent exposure concentrations (factor of 1.0 -
1.2).

Nominal concentrations: 18, 32 and 56 µg/L
Mean measured concentrations: 15.8, 30.7 and 50.8 µg/L

Details on test conditions:

Test vessel: 400-mL glass beakers. Each beaker contained 250 mL of test solution and 10 daphnids
per vessel.
Aeration: none
Type of flow-through (e.g. peristaltic or proportional diluter): Flow through conditions. 12 volume turnovers per day.
Renewal rate of test solution (frequency/flow rate): Diluter system delivered fresh test solutions once every two hours.
No. of organisms per vessel: Four replicates of 10 daphnids each at each test level. The solvent used was acidified methanol at 0.1 mL/L. This was methanol with 1 volume-percent glacial acetic acid. Control, solvent control, 5.6, 10, 18, 32 and 56 µg/L.
No. of vessels per concentration (replicates): 10 daphnids per replicate for a total of 40 organisms per treatment level. Loading was 1 daphnid per 25 mL of test solution. Control, solvent control, 5.6, 10, 18, 32 and 56 µg/L.

Source/preparation of dilution water: “M7 medium” was used as the dilution water for testing and breeding of the daphnids.
Total organic carbon: TOC = < 2 mg/L

Lighting: 16 hours light and 8 hours dark and approximately 700 lux

Parameters measured including the sublethal effects: Daily observations were done for mortality, immobility, and others behavioral sublethal effects. Immobility was equivalent to mortality in this study.
Observation intervals: Daily

Vehicle control performed: Yes

Range finding study:
The Daphnia magna were exposed to spirodiclofen technical in a static acute test. The range find included a dilution water control, solvent control (dimethylformamide at 0.1 ml/L) and nominal concentrations from 0.1 to 10,000 ug ai/L spaced by a factor of 10.
The solubility limit of spirodiclofen technical was not addressed in this range find test. There were no mortalities at any treatment level in the range find. The definitive study test levels were based upon the range find results and the solubility limit in water (50 ug ai/L).

Water quality acceptable: Yes
Were raw data included? Yes

Reference substance (positive control):

yes

Remarks:

K2Cr2O7

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 50.8 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

mortality

Details on results:

"Daphnia magna
24-h EC50 >50.8 µg/L (measured)
48-h EC50 >50.8 µg/L (measured)
Flow-through test conditions: no effects within the limit of solubility"

Results with reference substance (positive control):

K2Cr2O7. Acute toxicity test using 0.75, 1.00, 1.33, 1.78, 2.37 and 3.16 mg/L test concentrations.

Reported statistics and error estimates:

No statistical analysis was possible since do dose-response was observed. No difference compared to the solvent control.

Table 3: Effect of spirodiclofen Technical on mortality of Daphnia magna

Treatment (µg/L) [Nominal conc.]	No. of organisms	Observation period
		24 hours		48 hours
		No Dead	% mortality	No Dead	% mortality
Control	40	0	0	0	0
Solvent control	40	0	0	1	2.5
5.6	40	0	0	0	0
10	40	0	0	0	0
18	40	0	0	1	2.5
32	40	0	0	1	2.5
56	40	1	2.5	1	2.5
NOEC			56 µg/L		56 µg/L
EC50			> 56 µg/L		> 56 µg/L
Positive control K2Cr2O7.	24 hour EC50 = 1.20 mg/L (95% CI = 1.08 - 1.32 mg/L). Gradient of the line of regression was s = 1.52.

Validity criteria fulfilled:

not applicable

Conclusions:

Test Organism Age: first instar, less than 24 hours old
Test Type: Flow through
24-hour NOEC >50.8 µg/L.
48-hour NOEC >50.8 µg/L.
24-hour EC50 >50.8 µg/L.
48-hour EC50 >50.8 µg/L.
Endpoint(s) Effected: No mortality was observed in this 48-hour study. No sublethal effects were noted in the study.

Executive summary:

The 48-hr acute toxicity of spirodiclofen technical to Daphnia magna was studied under flowthrough conditions. The animals in the definitive test were exposed to a dilution water control and the nominal concentrations of 5.6, 10, 18, 32, and 56 µg/L. The 24- and 48-hour EC₅₀ for spirodiclofen technical was greater than 50.8 µg/L. Based on the results of this study, spirodiclofen would be classified as very highly toxic to Daphnia magna in accordance with the classification system of the U. S. EPA. This classification is somewhat misleading in this case. The maximum solubility for spirodiclofen is less than 0.1 mg/L which automatically classifies the result as “very highly toxic” despite the lack of mortality and sublethal effects in this 48 hour study. This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates

Description of key information

The 48-hr acute toxicity of spirodiclofen technical to Daphnia magna was studied under flowthrough conditions. The animals in the definitive test were exposed to a dilution water control and the nominal concentrations of 5.6, 10, 18, 32, and 56 µg/L. The 24- and 48-hour EC50 for spirodiclofen technical was greater than 50.8 µg/L. This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

> 50.8 µg/L