1-[2-(allyloxy)ethyl-2-(2,4-dichlorophenyl)-1H-imidazolium hydrogen sulphate

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

bioaccumulation in aquatic species: fish

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:

OECD Guideline 305 E (Bioaccumulation: Flow-through Fish Test)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: BEB191, synthesized in own laboratories. Because the solubility of the free base was too low to prepare the required stock solutions, a sufficient amount was transformed to the sulphate salt and received the batch number PFA011.
- Expiration date of the lot/batch: not indicated
- Purity test date: not indicated

Radiolabelling:

no

Details on sampling:

- Sampling intervals/frequency for test organisms:
* accumulation: 4, 8, 16, 32, 48, 96, 168 h
* depuration: 180, 192, 216, 240, 264 h
- Sampling intervals/frequency for test medium samples:
* accumulation: 0, 2, 3, 4, 8, 16, 32, 48, 96, 168 h
* depuration: 172, 176, 180, 192, 216, 240, 264 h
- Sample storage conditions before analysis: all samples were frozen at 20°C until determination of the test substance concentration
- Details on sampling and analysis of test organisms and test media samples (e.g. sample preparation, analytical methods): Upon each sampling occasion, fish from the aquaria with test substance were considered as individual samples, whereas fish from the control aquarium were pooled.
To check for a possible contamination of the test substance, some fish from the stock culture were homogenised (Ultra-Turrax). The homogenate was stored at -20°C until analysis.

Vehicle:

no

Details on preparation of test solutions, spiked fish food or sediment:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Imazalil from batch BEB191, synthesized in own laboratories and with a purity of 97.6% was used. Because the solubility of the free base was too low to prepare the required stock solutions, a sufficient amount was transformed to the sulphate salt and received the batch number PFA011 (purity 99.5%).
- Controls: yes
- Evidence of undissolved material (e.g. precipitate, surface film, etc): none indicated

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Common name: rainbow trout
- Strain: certified by the supplier to belong to the genus Salmo
- Source: local hatchery (Wijnant-Meussen, Voeren)
- Length at study initiation (length definition, mean, range and SD): 5.87 cm, standard deviation 0.37cm, 95% confidence interval 5.73-6.01cm
- Weight at study initiation (mean and range, SD): 1.96g, standard deviation 0.46g, 95% confidence interval 1.78-2.13g
- Lipid content at test initiation (mean and range, SD): 2.3% fat content
- Health status: Upon arrival at the test facilities, the fish were free from diseases and malformations.
- Feeding during test
- Food type: commercial dry fish food
- Amount: 2% of the wet fish weight
- Frequency: daily

ACCLIMATION
- Acclimation period: 48 hours
- Health during acclimation (any mortality observed): Fish were immediately transferred to an aquarium with a permanent flow-through of tap water. The mortality during the acclimation period recorded after a settling-in period of 48 hours was < 5%, so that the lot was accepted.

Route of exposure:

aqueous

Justification for method:

minimised test method used to support BCF estimates based on Kow

Test type:

flow-through

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

168 h

Total depuration duration:

92 h

Hardness:

155.2 mg/l CaCO3 (first week)
159.4 mg/l CaCO3 (second week)

Test temperature:

14.65 °C (mean measured)

pH:

7.99 (mean measured)

Dissolved oxygen:

10.36 mg/l O2 (mean measured)

TOC:

not indicated

Salinity:

not applicable

Conductivity:

not applicable

Details on test conditions:

TEST SYSTEM
- Test vessel: aquaria
- Material, size, headspace, fill volume: all-glass aquaria with a 40l capacity
- Aeration: the aquaria were fitter out with an aeration device and covered with a glass pane to prevent the fish from jumping out
- Type of flow-through (e.g. peristaltic or proportional diluter): The metering system consisted of a supply of cooled filtered tap water, flow meters, a peristaltic pump, brown 5l jars containing a concentrated stock solution of the test substance and static mixers.
- Renewal rate of test solution (frequency/flow rate): The flow rate of the tap water was adjusted with the flow meters at 139 ml/min. A flow rate of 1 ml/min of the concentrated stock solution of the test substance was adjusted with the peristaltic pump. Both streams were mixed in the static mixers and brought into the aquaria. At this rate, the aquaria were renewed 5x/day.
- No. of organisms per vessel: 48
- No. of vessels per concentration (replicates): 1
- No. of vessels per control / vehicle control (replicates): 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Tap water, dechlorinated over activated charcoal, was used as dilution water.
- Intervals of water quality measurement: measurements took place on days 0, 1, 2, 3, 6, 7, 8, 9, 10, 11
- Intervals of test medium replacement: the aquaria were renewed 5x/day

OTHER TEST CONDITIONS
- Photoperiod: 16h light - 8h dark
- Light intensity: fluorescent lamp (Philips 58W/33)

Nominal and measured concentrations:

Nominal concentration: 0.025 mg imazalil /L
Time (h) 0 2 3 4 8 16 32 48 96 168 172 176 180 192 216 240 264
Concentration in medium (µg/ml) 0.0166 0.0130 0.0163 0.0124 0.0162 0.0148 0.0210 0.0166 0.0194 0.0220 - - - - - - -
Mean concentration in fish (µg/g) - - - 0.734 0.852 0.783 0.967 1.030 1.180 1.050 - - 0.318 0.221 0.108 0.062 -

Nominal concentration: 0.25 mg imazalil /L
Time (h) 0 2 3 4 8 16 32 48 96 168 172 176 180 192 216 240 264
Concentration in medium (µg/ml) 0.245 0.187 0.198 0.190 0.197 0.313 0.225 0.199 0.212 0.445 - - - - - - -
Mean concentration in fish (µg/g) - - - 5.43 7.24 8.87 9.21 8.87 9.64 10.0 - - 2.88 1.10 0.54 0.30 0.27

Reference substance (positive control):

no

Details on estimation of bioconcentration:

BASIS INFORMATION
- Measured/calculated logPow: 3.82

BASIS FOR CALCULATION OF BCF
- Estimation software: SAS-NLIN (Non Linear Regression Program) was used to calculate the depuration and redistribution rate constants and to fit a curve through the experimental points

Key result

Conc. / dose:

0.025 mg/L

Temp.:

15 °C

pH:

8

Type:

BCF

Value:

63.8 dimensionless

Key result

Conc. / dose:

0.25 mg/L

Temp.:

15 °C

pH:

8

Type:

BCF

Value:

48.7 dimensionless

Rate constant:

overall depuration rate constant (d-1)

Remarks:

alpha

Value:

0.493

Remarks on result:

other: 0.025 mg/l test concentration

Rate constant:

overall depuration rate constant (d-1)

Remarks:

beta

Value:

0.025

Remarks on result:

other: 0.025 mg/l test concentration

Rate constant:

overall depuration rate constant (d-1)

Remarks:

alpha

Value:

0.148

Remarks on result:

other: 0.25 mg/l test concentration

Rate constant:

overall depuration rate constant (d-1)

Remarks:

beta

Value:

0.016

Remarks on result:

other: 0.25 mg/l test concentration

Rate constant:

overall uptake rate constant (L kg-1 d-1)

Value:

14.3

Remarks on result:

other: 0.025 mg/l test concentration

Rate constant:

overall uptake rate constant (L kg-1 d-1)

Value:

5.5

Remarks on result:

other: 0.25 mg/l test concentration

Details on kinetic parameters:

- Uptake rate constant k(s):
* test concentration 0.025 mg/L: 14.3 1/h
* test concentration 0.25 mg/L: 5.5 1/h

- Depuration rate constant k(e):
* test concentration 0.025 mg/L: alpha = 0.493 1/h, beta = 0.025 1/h
* test concentration 0.25 mg/L: alpha = 0.148 1/h, beta = 0.016 1/h

A graphical representation of the experimental data and fitted curves calculated with SAS-NLIN shows that for both test substance concentrations a rapid depuration of Imazalil has occured. However, the depuration curve is not linear on the log concentration versus time plot, as is to be expected for the first-order depletion process - frequently proposed in literature - for the elimination of xenobiotics from fish. In contrast, the depuration curve seemed to be composed of a sum of two first-order depletion phases. The calculated terminal elimination half-life was 27.3 h after the 0.025 mg/l exposure and 43.3 h after the 0.25 mg/l exposure. This meant that imazalil was rapidly eliminated by the Rainbow trout (Salmo gairdneri) which is in agreement with previous observations in mammals and birds.

Details on results:

- Mortality of test organisms: no fish died within the given test period
- Behavioural abnormalities: fish subjected to either exposure level did not react different from the control group
- Mortality and/or behavioural abnormalities of control: none indicated

Validity criteria fulfilled:

yes

Conclusions:

The bioaccumulation of Imazalil in fish was investigated according to the OECD guideline 305E with the test species Salmo gairdneri (Rainbow trout). The fish were exposed to two test concentrations, 0.025 and 0.25 mg Imazalil /L, and the corresponding bioconcentration factors were calculated as 63.8 and 48.7 respectively. The terminal elimination half-life was in the range from 27.3 to 43.3h. The calculated BCF values were lower than theoretical predictions based upon the octanol-water partition coefficient of Imazalil and the fish eliminated and/or transformed the test substance, which prevented a build-up in their tissues.

Reference 2

Endpoint:

bioaccumulation in aquatic species: fish

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

Conc. / dose:

0.025 mg/L

Temp.:

15 °C

pH:

8

Type:

BCF

Value:

63.8 dimensionless

Key result

Conc. / dose:

0.25 mg/L

Temp.:

15 °C

pH:

8

Type:

BCF

Value:

48.7 dimensionless

Description of key information

The study of Weytjens et al. (1995) investigating the bioaccumulation of Imazalil in fish was considered as the key study for endpoint converage. The study was carried out according to the OECD guideline 305E with the test species Salmo gairdneri (Rainbow trout). The fish were exposed to two test concentrations, 0.025 and 0.25 mg Imazalil /L, and the corresponding bioconcentration factors were calculated as 63.8 and 48.7 respectively. The terminal elimination half-life was in the range from 27.3 to 43.3h. The calculated BCF values were lower than theoretical predictions based upon the octanol-water partition coefficient of Imazalil and the fish eliminated and/or transformed the test substance, which prevented a build-up in their tissues.

Key value for chemical safety assessment

BCF (aquatic species):

63.8 dimensionless