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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Reference
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:
other: GLP Guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 305 C (Bioaccumulation: Test for the Degree of Bioconcentration in Fish)
Principles of method if other than guideline:
Modified for use with Mytilus edulis
GLP compliance:
yes
Details on sampling:
Both controls were sampled weekly
Treatments sampled at end of exposure
Visual comparisons three times weekly
Vehicle:
yes
Details on preparation of test solutions, spiked fish food or sediment:
DMSO used as a solvent. 0.096 ml/L DMSO used as solvent control
Quantities of ca. 166.67 mg and 1666.66 mg of test substance accurately weighed then dissolved in 500ml DMSO resulting in stock solutions of 333.34 and 3333.32 mg/L
Test organisms (species):
other aquatic mollusc: Mytilus edulis
Details on test organisms:
TEST ORGANISM
- Common name: Blue mussel
- Source: Commercial mussel beds in Eastern Schelde estuary
- Length at initiation: 27.1 ± 0.29 mm
- Weight at termination: 0.56 ± 0.21 g

ACCLIMATION
- Acclimation period: In laboratory for 48 days in seawater at 15 °C
Route of exposure:
aqueous
Test type:
flow-through
Water / sediment media type:
natural water: marine
Total exposure / uptake duration:
42 d
Test temperature:
15 °C
pH:
7.6-8.2
Dissolved oxygen:
lowest value: 7.2 mg/L
Salinity:
3.19 - 32.6%
Details on test conditions:
TEST SYSTEM
- Test vessel: glass aquaria (length x width = 58.6 x 5.05 cm)
- Aeration: only during feeding periods
- Renewal rate of test solution (frequency/flow rate): flow rate of 500 L per 24 h, regulated by hydrostatic pressure
- No. of organisms per vessel: 120

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: seawater collected from clean source at Eastern Schelde estuary

OTHER TEST CONDITIONS
- Photoperiod: 16:8 h Light:dark regime

RANGE-FINDING / PRELIMINARY STUDY
Adopted a theoretical 96 h LC50 of 32 mg/L on which to base test concentrations
Nominal and measured concentrations:
0.32 and 0.032 mg/L
Measured values did not deviate from nominal by more than 10%
Details on estimation of bioconcentration:
Estimated using following equation:

BCFn = Cf,n - Cf,b/Cw

BCFn = concentration factor after n weeks
C f,n = Concentration of test compound in the mussels flesh after n week exposure
C f,b = Arithmetical mean concentration of the test compound in the mussels body at the start of and at the termination of the control test
Cw = Mean concentration of the test compound in the water
Temp.:
15 °C
Type:
BCF
Value:
5.2 dimensionless
Basis:
whole body w.w.
Calculation basis:
steady state
Remarks on result:
other: pH value 7.6 - 8.2; Concentration: 0.32 and 0.032 mg/L
Details on results:
The values achieved in the low and high concentration are considered to be similar and it is assumed that the BCF in mussel tissue was concentration independent.
Some mortality occured but deemed negligible (< 1%)

The BCF after exposure to two concentrations of preventol A6 for 42 d was found to be 5.2 on average (range: 4.4 -6.6, based on wet weight tissue concentration of the substance

Executive summary:

A GLP Guideline study is available for this substance, modified for use with Mytilus edulis. Considering the low logPow (< 3) for Diuron this substance is not expected to bioaccumulate and a bioaccumulation study is not necessary. Nevertheless, the results of this study confirm the low potential of Diuron to bioaccumulate with the determination of a low BCF of 5.2.

Description of key information

Due to the low logPow (2.89), an accumulation in aquatic organisms is not expected.  

Key value for chemical safety assessment

Additional information

A calculated BCF of 57.1 confirms the low potential of Diuron to accumulate in the aquatic food chain. Experimental data are not considered necessary. However, a GLP Guideline study is available for this substance, modified for use with Mytilus edulis. The calculated BCF of 5.2 confirms the low potential for Diuron to bioaccumulate in aquatic organisms.