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Sediment toxicity

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Endpoint:
sediment toxicity: long-term
Type of information:
experimental study
Adequacy of study:
key study
Study period:
7 December 1995 to 12 January 1996
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
ASTM E1383 (Sediment Toxicity Test (Media: Sediment-freshwater))
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: DoE toxicity tests in support of environmental quality standards (final report DoE3460(P) (S Vine & M crane)
GLP compliance:
yes
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
* Non-radiolabelled imazalil (used for toxicity test)
- Source and lot/batch No.of test material: STAN-9404-014-1
- Expiration date of the lot/batch: July 1998
- purity: 99.8%

* Non-radiolabelled imazalil sulphate (used for determination of Kd)
- Source and lot/batch No.of test material: V840-413
- Expiration date of the lot/batch: July 1996
- purity: 100.43%

* Radiolabelled imazalil (used for toxicity test and determination of Kd)
- Source and lot/batch No.of test material: 1154
- Expiration date of the lot/batch: 29 May 1996
- purity: 99.2%

RADIOLABELLING INFORMATION (if applicable)
- Radiochemical purity: 99.2%
- Specific activity: 26.85 MBq
- Locations of the label: 14C
- Expiration date of radiochemical substance: 29 May 1996

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: not indicated
- Stability under test conditions: the radiochemical purity of (14C)-imazalil as determined by HPLC was 97.5% and 91.1% in the overlying water at the start and end of the 17 day test; the corresponding purity in the sediment was 98.7% and 93.1%

Analytical monitoring:
yes
Details on sampling:
SEDIMENT
- Concentrations: sediments were extracted using methanol (100 mL)
- Sampling interval: one day before the start (addition of the larvae) and days 0, 1, 4, 7, 14, 17 (test end)
- Sample storage before analysis: not indicated

OVERLYING WATER
- Concentrations: 1 mL aliquots of test medium were taken from the test vessels
- Sampling interval: daily
- Sample storage before analysis: not indicated
Vehicle:
no
Details on sediment and application:
PREPARATION OF SPIKED SEDIMENT
- Preparation of radiodilutions for spiking sediment: Radiodilutions of imazalil were prepared by mixing non-radiolabelled imazalil and radiolabelled (14C)-imazalil (equivalents) in 250 mL dilution water. The non-radiolabelled imazalil was added to dilution water and then sonicated for approximately two hours before adding the radio-labelled (14C)-imazalil.
- Details of spiking: Clean sediment was spiked with a series of concentrations of imazalil prepared as a radiodilutions of (14C)-imazalil sulphate with non-radiolabelled imazalil. The radiodilution was used to spike sediment/water suspensions, before shaking. Approximately 800g of wet sediment (equivalent to approximately 380g dry sediment) was weighed into 1 liter amber glass bottles treated with 'Aquasil' (a siliconising fluid used to reduce adsorption). The appropriate stock was then added to the sediment contained in the amber glass bottles. The bottles were then placed on a shaker overnight. The dosed sediment was then distributed between the appropriate vessels. The vessels were then placed in the flow-through system immediately after addition of the test sediment to the test vessels.
- Controls: yes

PREPARATION OF SPIKED WATER
- Preparation of radiodilutions for overlying water: Radiodilutions of imazalil were prepared by mixing non-radiolabelled imazalil with radiolabelled (14C)-imazalil sulphate, in 10 mL of acetone. The quantities of non-radiolabelled imazalil, used in the radiodilutions, were calculated based on the sulphate salt of imazalil.
- Details of spiking: Approximately 5L of dilution water was added to each glass aspirator and a 0.25 mL aliquot of the appropriate radiodilution added before adding the remaining dilution water. The target specific radioactivity in the overlying water was 53.8 dpm/mL for the nominal 0.002 mg/L treatment and 500 dpm/mL for the remaining treatments.
- Controls: yes (water control and acetone control)
Test organisms (species):
Chironomus riparius
Details on test organisms:
TEST ORGANISM
- Common name: harlequin fly
- Strain/clone: not indicated
- Source: from a laboratory culture set up at Corning Hazleton (Europe) from egg ropes supplied by the University of Sheffield
- Breeding conditions: larvae were maintained in silver sand
- Age of animals at beginning of exposure: 6 day old larvae
- Feeding during test: yes
- Food type: ground TetraMin(TM)
- Amount: 0.016 g per vessel
- Frequency: Monday, Wednesday, Friday

ACCLIMATION
- Acclimation period: on the day of the start of the test, the larvae were sieved out of the silver sand and held in freshwater of the same composition and quality as that to be used in the toxicity test, before addition to the test vessels
- Acclimation conditions (same as test or not): yes
Study type:
laboratory study
Test type:
flow-through
Water media type:
freshwater
Type of sediment:
natural sediment
Limit test:
no
Duration:
17 d
Exposure phase:
total exposure duration
Hardness:
78 mg/L CaCO3 (mean)
Test temperature:
19.2 °C (mean minimum) - 20.0 °C (mean maximum)
pH:
7.2 (mean)
Dissolved oxygen:
87-92 % air concentration (mean)
Salinity:
not applicable
Ammonia:
not indicated
Conductivity:
not applicable
Nominal and measured concentrations:
Overlying water:
- Nominal concentrations: 0.002, 0.02, 0.2, 2 mg/l
- Mean measured concentrations: 0.001, 0.0114, 0.1814, 1.5798 mg/l

Sediment:
* Nominal concentrations: 0.46, 3.27, 23.24, 165.4 mg/kg
* Mean measured concentrations: 0.51, 4.29, 27.5, 228 mg/kg
Details on test conditions:
TEST SYSTEM
- Test container (material, size): 400 ml "tall form" glass beakers
- Sediment volume: 50 ml test sediment
- Overlying water volume: 250 ml

EXPOSURE REGIME
- Feeding regime: Monday, Wednesday, Friday
- Type and preparation of food: ground TetraMin(TM)
- Amount of food: 0.016 g per vessel
- For the imazalil dosed treatments, 20C. riparius larvae were randomly allocated to four vessels. To the remaining analytical desginated vessels per treatment, 10C. riparius larvae were randomly allocated to seven vessles and 20 larvae to two vessels.


RENEWAL OF OVERLYING WATER
- Details on volume additions: 5 volume replacements per day
- Flow-rate: 0.7 mL/min

OVERLYING WATER CHARACTERISTCS
- Source of water: the water used for culturing and for the sediment test with C. riparius was the laboratory mains supply

SOURCE OF NATURAL SEDIMENT
- Location and description of sampling site: test sediment was obtained commercially from Millstream pond by the Institute of Freshwater Ecology
- Contamination history of site: the site is known to be free of contamination

HANDLING OF NATURAL SEDIMENT
- Treatment: The sediment was diluted with silversand to give an organic carbon content of approximately 3.76% (organic matter content of 6.48%). The sediment was sieved to 0.5 mm before dilution. The sediment was homogenised before use.
- Storage conditions: in darkness at 4°C

OTHER TEST CONDITIONS
- Photoperiod: 16h daylength

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
The effect measured was emergence, which is considered equivalent to survival. The C. riparius were observed daily after the onset of emergence. The number of adults collected in nets placed over the test vessels were recorded and removed daily.

Reference substance (positive control):
no
Key result
Duration:
17 d
Dose descriptor:
NOEC
Effect conc.:
27.5 mg/kg sediment dw
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
emergence rate
Duration:
17 d
Dose descriptor:
LOEC
Effect conc.:
228 mg/kg sediment dw
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
emergence rate
Duration:
17 d
Dose descriptor:
NOEC
Effect conc.:
0.181 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
emergence rate
Duration:
17 d
Dose descriptor:
LOEC
Effect conc.:
1.58 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
emergence rate
Details on results:
- Percent emergence per replicate and test concentration: For each treatment 80% or greater emergence was observed by the end of the 17 day exposure duration.

Validity criteria fulfilled:
yes
Conclusions:
The toxicity of Imazalil to Chironomus riparius was determined in a 17 day flow-through test according to ASTM 1383-94. The highest measured concentrations resulting in no observable reduction of emergence, hence survival of C. riparius after 17 days exposure (NOEC), was 0.1814 mg/L and 27.5 mg/kg in the overlying water and sediment respectively. The results of the test can be considered reliable without restriction.
Endpoint:
sediment toxicity: long-term
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Data from the related substance imazalil base is used to cover this endpoint. The justification for read across is attached in IUCLID Section 13.
Reason / purpose for cross-reference:
read-across source
Key result
Duration:
17 d
Dose descriptor:
NOEC
Effect conc.:
36.6 mg/kg sediment dw
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
emergence rate

Description of key information

The study of Wyness (1996), investigating the toxicity of Imazalil sulphate in Chironomus riparius according to ASTM 1383 -94, was considered as the key study for endpoint coverage. A NOEC of 27.5 mg imazalil /kg was found after an exposure of 17 days in freshwater, which corresponds to 36.57 mg imazalil sulphate/kg sediment dw .

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater sediment:
36.57 mg/kg sediment dw

Additional information