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

Sediment toxicity

Link to relevant study record(s)

Reference

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

other: BBA

Version / remarks:

“Effects of plant protection products on the development of sediment-dwelling larvae of Chironomus riparius in a water sediment system” 1995.

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sediment and application:

The test sediment used was artificial sediment which was prepared 6 days before the start of the test. It consists of 69 % fine quartz sand (84 % of the sand has a particle size of 0.06 - 0.2 mm), 10 % dried, finely ground peat (sphagnum peat; pH 2 - 4), 20 % kaolin (kaolinite content of about 36 %, pH value ca 7, "Kaolin W", from Erbsloh / Geisenheim) and around 1 % calcium carbonate (pure) to adjust the pH value to 6 ± 0.5 (figures refer to dry weight).

Test organisms (species):

Chironomus riparius

Details on test organisms:

Species: Midge, Chironomus riparius
Age of the parental stock: adult stock culture of 21 to 28 days in age.
Source: Laboratory culture maintained since 1991. Original source: University of Sheffield (UK).
Parental acclimation: Culture has been maintained in lab since 1991. Adults were 21 to 28 days old and the larvae randomly selected for testing were 2 to 3 days post-hatch or L1 stage larvae.
Fed an aqueous suspension of fish food (Tetra Phylla) approx. 3 times per week.
Static water-sediment system with gentle aeration. The aeration was removed for 24 hours after organisms were added to vessels and then aeration was restarted.
Parent acclimation:
Feeding: The same food was used for testing and culturing the midges. An aqueous suspension of commercial ornamental fish food (Tetra Phyll) as 1 g food/20 mL water. Fed each test vessel at least 3 times per week during the study.

Study type:

laboratory study

Test type:

static

Water media type:

freshwater

Type of sediment:

artificial sediment

Duration:

28 d

Exposure phase:

total exposure duration

Hardness:

Test water: 196 mg/L CaCO3

Test temperature:

20 ± 2°c

pH:

8.0

Dissolved oxygen:

Test water: 9.3 mg/L

Nominal and measured concentrations:

During the study, the measured concentrations of the test item in the test water were analyzed
three times on days 0, 7 and 28 at the initial nominal concentrations of 0.010, 0.10 and 1.0
mg/L.

Details on test conditions:

Test and breeding water was prepared as "M7-medium" as documented in the "Original Draft" of an EEC Daphnia magna Pilot Ring Test. The "M7-medium" is similar to the "M4-medium" which is described in: B.-P. ELENDT and W.-R. BIAS: Trace Nutrient Deficiency in Daphnia magna Cultured in Standard Medium for Toxicity Testing. Effects of the Optimisation of Culture Conditions on Life History Parameters of D. magna, Water Research 24 (9), 1157-1167, 1990. The medium is prepared using deionised water and adding mineral salts and vitamins (reagent grade chemicals). The water was aerated and temperated to 20 °C in an in-house preparation tank.
Test containers were 3 L glass beakers with an average diameter of about 13.5 cm.

Reference substance (positive control):

no

Key result

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

0.094 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

emergence rate

Key result

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

0.035 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

emergence rate

Reported statistics and error estimates:

At the termination of the study data obtained on number of emerged midges as well as the date of emergence (development rate) were statistically analyzed to establish the EC15 and EC50. Statistical calculations were processed with the aid of the statistical MS-DOS software package "EASY ASSAY" written by H.T. Ratte, Technical University of Aachen. The chi-test is performed to establish different sensitivities of sexes. Because it is not possible to introduce the same number of female and male organisms as larvae into the individual test beakers, an evaluation of the emergence rate cannot be performed for individual sexes. Thus, for the statistical analysis of the emergence rate, male and female results are pooled. The evaluation of the development time and rate is performed for each sex. The raw data are statistically evaluated in three steps:
1.The calculation of per-vessel statistics.
2.The calculations of per-treatment statistics.
3.The determination of effective concentrations such as the ECx or statistically significant threshold concentrations such as the NOEC and LOEC.

Validity criteria fulfilled:

yes

Conclusions:

The EC10 and EC50 based upon the emergence rate was 35 and 94 µg/L, respectively. Emergence was the most sensitive endpoint in the study.

Executive summary:

The study was performed with water and sediment under static conditions. The test containers were prepared 6 days prior to test initiation. On the day before test initiation the study animals, stage L1 larvae, were randomly added to the test chambers. The test item was applied to the water surface on Day 0 to create a nominal water concentration of 10, 32, 100, 180, 320, 560 and 1000 µg /L (ppb). The study included a control and solvent control treatment, as well.
The 28-day study included observations of behavior and record of the sex, time and number of emerged adults. This data was used to determine the development rate, emergence rate and mortality in the treatments as compared to the control and solvent controls.
The initial measured concentrations in the water column were determined 1 hour after application. The 10, 100 and 1000 ppb treatments were analyzed and the measured concentrations were 80 to 89% of the nominal. Further analysis was done on Day 7 and 28 to document the natural degradation of the compound in the water-sediment system. The Day 7 results indicated less than 15% of the nominal parent concentration in the overlying water, and on Day 28 less than 3% of the parent remained.
The EC05, EC10, EC15 and EC50 based upon the emergence rate was 26, 35, 42 and 94 µg/L, respectively. Emergence was the most sensitive endpoint in the study.
The EC15 for development rate could not be calculated since there were no adverse effects on those treatment levels with emergence. The 320, 560 and 1000 µg /L treatments had 0% emergence. Statistical analysis of the treatment levels with emergence, the 10, 32, 100 and 180 µg /L levels, indicated no difference in development as compared to the controls. Therefore, the development rate was not influenced up to 180 µg /L.
This study is acceptable, but is classified as supplemental since there is no PMRA or USEPA guideline requirement for the 28-day evaluation of development and emergence of the sediment dwelling insect, Chironomus riparius.

Description of key information

In a GLP study according to BBA-Guideline "Effects of plant protection products on the development of sediment-dwelling larvae of Chironomus riparius in a water-sediment system" from 1995, an EC₁₀ of 0.035 mg/L was observed for the emergence rate of Chironomus riparius in a water sediment system (water spiked). 

Key value for chemical safety assessment