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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From Februaru 2011 to May 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study (OECD, EPA, etc)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2012

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)
Deviations:
no
Qualifier:
according to
Guideline:
other: ASTM Standard E729-96: Standard Guide for Conducting Acute Toxicity Tests on Test Materials with Fishes, Macroinvertebrates and Amphibians
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): XP-7866
- Physical state: Solid
- Lot/batch No.: 10188-1JM
- Expiration date of the lot/batch: February 28, 2015
- Storage condition of test material: Stored under ambient conditions
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
PHYSICO-CHEMICAL PROPERTIES, refer to chapter 4 for details on test item.

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
- Sampling method: Samples were collected from the batches of test solution prepared for each treatment and control group at the beginning of the test and at 24 hours, and from each test chamber prior to renewal at 24 hours and at 48 hours (± 1 hour) to measure concentrations of the test substance. The samples were collected at mid-depth, placed in glass vials.
- Sample storage conditions before analysis: Processed immediately for analysis.

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:
1) Primary stock solution in methanol, for a nominal concentration of 100 mg a.i./mL
2) The stock solution was sonicated for approximately 3 minutes and inverted at least 20 times to mix, and appeared clear and colorless with no visible precipitate. An appropriate volume of the stock solution that would result in the nominal test solution concentration was transferred to a clean, empty 2000 mL volumetric flask using an Eppendorf™ pipette or a glass graduate pipette.
3) The methanol was evaporated off from the flasks under a stream of nitrogen gas.
4) The flasks were brought to volume with pH adjusted well water to prepare the five nominal test concentrations of 20, 40, 80, 160 and 320 μg a.i./L. The test solutions were inverted to mix.
- Controls: Dilution water
The dilution water was prepared at the beginning of the test and at renewal on Day 1 of the test by adding aliquots of HEPES buffer to 15 L of UV sterilized well water and mixed using a whisk until the final pH of approximately 7 was achieved. A total of 15 g of HEPES buffer was used at each preparation.
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): methanol for the primary stock solution but evaporated in later stage (refer method above)
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no - All test solutions appeared clear and colorless.

Test organisms

Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Source: obtained from cultures maintained by Wildlife International, Ltd., Easton, Maryland.
- Age at study initiation (mean and range, SD): Daphnid neonates less than 24 hours old.
- Method of breeding: The four adult daphnids used to supply neonates for the test were held for 26 days prior to collection of the juveniles for testing, and had each produced at least one previous brood. Adult daphnids in the culture had produced an average of at least three young per adult per day over the 7-day period prior to the test. The adults showed no signs of disease or stress and no ephippia were produced during the holding period.
- Feeding during test: No


ACCLIMATION (Adult daphnids used to supply neonates)
- Acclimation period: 26 days prior to collection of the juveniles for testing
- Acclimation conditions (same as test or not): During the 2-week period immediately preceding the test:
* water temperatures in the cultures ranged from 19.9 to 21.4ºC, measured with a hand-held, liquid-in-glass thermometer.
* pH of the water ranged from 8.3 to 8.5, measured with a Thermo Orion Model 525Aplus pH meter.
* dissolved oxygen concentrations were >=7.3 mg/L (>=81% of saturation), measured with a Thermo Orion Model 850Aplus dissolved oxygen meter.
- Type and amount of food: Adult Daphnids in the cultures were fed daily a mixture of yeast, cereal grass media and trout chow (YCT), as well as a suspension of the freshwater green alga, Pseudokirchneriella subcapitata.
- Health during acclimation (any mortality observed): The adults showed no signs of disease or stress and no ephippia were produced during the holding period.

Study design

Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h

Test conditions

Hardness:
172 mg/L as CaCO3
Test temperature:
20 +/-1°C
pH:
ranged from 7.0 to 7.4
Dissolved oxygen:
>= 7.2 mg/L (>= 80% of saturation)
Nominal and measured concentrations:
- nominal concentrations 20, 40, 80, 160 and 320 μg active ingredient (a.i.)/L.
- mean measured test concentrations: 6.5, 15, 19, 36 and 79 μg a.i./L, representing 33, 38, 24, 22 and 25% of nominal concentrations, respectively.
Note: Measured concentrations of the samples collected from the newly prepared test solutions at 0 and 24 hours ranged from 6.95 to 55.3% of nominal for the 40, 80, 160 and 320 μg a.i./L treatment groups, and were less than the limit of quantitation (LOQ). for the solution at 20 μg a.i./L treatment group. Measured concentrations of the samples collected from the 24-hour old test solutions at 24 and 48 hours ranged from 17.9 to 52.9% of nominal. When the measured concentration was below the LOQ, a value equivalent to one half of the LOQ (5.00 μg a.i./L) was used in the calculation of the mean measured test concentration.
Details on test conditions:
TEST SYSTEM
- Test vessel: Test chambers were 250-mL glass beakers filled with approximately 220 mL of test water. The depth of the test water in a representative chamber was 6.3 cm.
- Renewal rate of test solution (frequency/flow rate): after 24-hours
- No. of organisms per vessel: 10 daphinds
- No. of vessels per concentration (replicates): Two replicates
- No. of vessels per control (replicates): Two replicates

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Obtained from a well approximately 40 meters deep located on the Wildlife International, Ltd. site. The well water was passed through a sand filter to remove particles greater than approximately 25 µm, and pumped into a 37,800-L storage tank where the water was aerated with spray nozzles. Prior to use, the water was filtered to 0.45 µm to remove fine particles and passed through an ultraviolet sterilizer
- Analyses of pesticides, organics and Metals of water were conducted by Lancaster Laboratories on samples collected on December, 28, 2011. Details are available in the original report.

OTHER TEST CONDITIONS
- Adjustment of pH: the ph of the dilution water was adjusted to pH neutral
- Photoperiod: 16 hours of light and 8 hours of darkness. 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: ambient laboratory light Fluorescent = 440 lux at test initiation at the surface of the water - Light bulbs that emit wavelengths similar to natural sunlight. Light intensity was measured at the water surface of one representative test chamber at test initiation using a SPERScientific Model 840006C light meter.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
* immobile organisms
Note: Immobility was defined as a lack of movement by the organism except for minor activity of the appendages.
* signs of toxicity
Note: Observations were made approximately 3, 24 and 48 hours (±1 hour) after test initiation.
Reference substance (positive control):
no

Results and discussion

Effect concentrationsopen allclose all
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
> 79 µg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
mobility
Remarks on result:
other: could not be calculated with the immobility data obtained.
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 79 µg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
mobility
Remarks on result:
other: could not be calculated with the immobility data obtained.
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
> 79 µg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
mobility
Remarks on result:
other: could not be calculated with the immobility data obtained.
Details on results:
Daphnids exposed to XP-7866 at concentrations ≤79 μg a.i./L appeared normal with no immobility or overt signs of toxicity.
Results with reference substance (positive control):
No reference substance
Reported statistics and error estimates:
The absence of immobile daphnids in any of the XP-7866 treatment groups during the test precluded the statistical calculation of EC50 values at 24 and 48 hours. Therefore, the EC50 values were estimated to be greater than the highest concentration tested. The no-immobility concentration and the no-observed-effect concentration (NOEC) were determined by visual interpretation of the immobility and observation data.

Any other information on results incl. tables

Conditions for the Validity of the Test:

The following criteria were used to judge the validity of the test:

1. immobility of the daphnids in the control did not exceed 10% by the end of the test; and

2. the dissolved oxygen concentration was ≥ 80% of the air-saturation value throughout the test.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The cladoceran, Daphnia magna, was exposed for 48 hours under static-renewal conditions to five mean measured concentrations of XP-7866 ranging from 6.5 to 79 μg a.i./L. The 48-hour EC50 value was greater than 79 μg a.i./L, the highest concentration tested. The 48-hour no-immobility concentration and the NOEC were both 79 μg a.i./L.