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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Reference
Endpoint:
bioaccumulation in aquatic species, other
Remarks:
mollusc
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Qualifier:
no guideline followed
Principles of method if other than guideline:
- Principle of test: The bioaccumulation of 4-methylbenzylidene camphor was investigated in mussel (Mytilus galloprovincialis).
- Short description of test conditions: Mussels were collected from the northwest Iberian coast and exposed to a single concentration of 1 µg/L test item in filtered seawater for 30 days (uptake period), followed by a 20 -day depuration period in untreated filtered seawater. The experiment was conducted in 30 L glass tanks, each containing six mussels, under semi-static regime with test media renewal every 48 hours (except the first day, which was renewed at 24 hours).
- Parameters analysed / observed: Test item concentrations were measured in mussels and test media
GLP compliance:
no
Remarks:
Published study from a peer-reviewed journal.
Radiolabelling:
no
Details on sampling:
- Sampling intervals/frequency for test organisms: After 0, 1, 2, 4, 8, 14, 22 and 30 d exposure, and after 2, 5, 9 and 20 d of depuration
- Sampling intervals/frequency for test medium samples: After 0, 1, 2, 4, 8, 14, 22 and 30 d exposure, and after 2, 5, 9 and 20 d of depuration
- Details on sampling and analysis of test organisms and test media samples: The stability of the test item in seawater was investigated in a preliminary experiment without the test animal and in the definitive test.
Vehicle:
yes
Remarks:
Dimethyl sulfoxide
Details on preparation of test solutions, spiked fish food or sediment:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Test item stock solutions were prepared in DMSO and stored in cold and darkness. DMSO concentration in the experiment was always under 0.1% (v/v).
- Chemical name of vehicle: DMSO
- Concentration of vehicle in test medium: <0.1% (v/v)
Test organisms (species):
other aquatic mollusc: Mytilis galloprovincialis
Details on test organisms:
TEST ORGANISM
- Common name: Mussel
- Source: Pristine area from the outer part of Ria de Vigo (NW Iberian coast)
- Length at study initiation: 40 to 50 mm long at collection
- Feeding during test
- Food type: Mixed diet of Isochrysis galbana, Tetraselmis suecica and Chaetoceros gracilis
- Frequency: Before each water change for 1 hour

ACCLIMATION
- Acclimation period: 1 week
Route of exposure:
aqueous
Justification for method:
aqueous exposure method used for following reason: representative exposure pathway for molluscs
Test type:
semi-static
Water / sediment media type:
natural water: marine
Total exposure / uptake duration:
30 d
Total depuration duration:
20 d
Test temperature:
16°C
Dissolved oxygen:
> 90% of saturation
TOC:
11.5 ± 2.1 uM DOC
Salinity:
34 ± 0.5‰
Details on test conditions:
TEST SYSTEM
- Test vessel: Glass tanks
- Material, size, headspace, fill volume: 30 L total volume
- Aeration: Continuous aeration with 0.22 um filtered air
- Renewal rate of test solution: Every 48 hours, except 24 hour renewal on Day 1
- No. of organisms per vessel: 6

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: 1 um filtered seawater collected from an uncontaminated area

OTHER TEST CONDITIONS
- Photoperiod: Constant darkness
Nominal and measured concentrations:
1 ug/L nominal concentration
Reference substance (positive control):
no
Details on estimation of bioconcentration:
As the data were highly variable and could not be fit to a bioaccumulation model, the peak concentration of test item in the mussels was reported as the maximum BCF.
Key result
Conc. / dose:
1 µg/L
Temp.:
16 K
Type:
BCF
Value:
801 L/kg
Basis:
whole body d.w.
Calculation basis:
other: Peak concentration
Remarks:
Data were highly variable and could not be fit to model
Details on results:
The test item bioaccumulation did not fit to that model due to the high variability of the data. Taking the peak concentration of test item in mussels recorded at day 14, a maximum BCF value of 801 L/kg can be obtained.

Table 1. Test item concentration measured in mussels exposed for 30 days to 1 µg/L and placed in clean seawater for 20 further days

 Exposure day  Measured test item concentration (ng/g dw)
 0  10.5
 1  418
 2  528.5
 4  437
 8  <LOQ
 14  801
 22  411
 30  9.5
 32  <LOQ
 35  <LOQ
 39  <LOQ
 50  5.5
Validity criteria fulfilled:
not specified
Conclusions:
A maximum BCF value of 801 L/kg was reported based on the peak concentration of test item in mussels during the uptake period.
Executive summary:

The bioaccumulation of 4-methylbenzylidene camphor was investigated in mussel (Mytilus galloprovincialis). Mussels were collected from the northwest Iberian coast and exposed to a single concentration of 1 µg/L test item in filtered seawater for 30 days (uptake period), followed by a 20 -day depuration period in untreated filtered seawater. A stock solution of the test item was prepared in dimethyl sulfoxide (DMSO), and the final concentration of DMSO in the test media was maintained below 0.1% (v/v). The experiment was conducted in 30 L glass tanks, each containing six mussels, under semi-static regime with test media renewal every 48 hours (except the first day, which was renewed at 24 hours). Samples of mussels and test media were taken for chemical analyses by LC-MS/MS after 0, 1, 2, 4, 8, 14, 22 and 30 days exposure, and after 2, 5, 9 and 20 days of depuration. The measured water concentrations were 0.87 µg/L at 30 mins, 0.61 µg/L at 24 hours and 0.42 µg/L at 48 hours. Measured test item concentrations in mussels were highly variable, therefore a bioaccumulation model could not be fit to the data. Taking the peak concentration of test item in mussels recorded at day 14, a maximum BCF value of 801 L/kg was obtained. This study is reliable with restrictions (Klimisch 2) as it was not conducted according to guideline, however the study is scientifically acceptable with minor limitations in experimental design and reporting (e.g. number of replicates).

Description of key information

A maximum BCF value of 801 L/kg was reported based on the peak concentration of test item in mussels during the uptake period.

Key value for chemical safety assessment

BCF (aquatic species):
801 L/kg ww

Additional information

The bioaccumulation of 4-methylbenzylidene camphor was investigated in mussel (Mytilus galloprovincialis). Mussels were collected from the northwest Iberian coast and exposed to a single concentration of 1 µg/L test item in filtered seawater for 30 days (uptake period), followed by a 20 -day depuration period in untreated filtered seawater. A stock solution of the test item was prepared in dimethyl sulfoxide (DMSO), and the final concentration of DMSO in the test media was maintained below 0.1% (v/v). The experiment was conducted in 30 L glass tanks, each containing six mussels, under semi-static regime with test media renewal every 48 hours (except the first day, which was renewed at 24 hours). Samples of mussels and test media were taken for chemical analyses by LC-MS/MS after 0, 1, 2, 4, 8, 14, 22 and 30 days exposure, and after 2, 5, 9 and 20 days of depuration. The measured water concentrations were 0.87 µg/L at 30 mins, 0.61 µg/L at 24 hours and 0.42 µg/L at 48 hours. Measured test item concentrations in mussels were highly variable, therefore a bioaccumulation model could not be fit to the data. Taking the peak concentration of test item in mussels recorded at day 14, a maximum BCF value of 801 L/kg was obtained. This study is reliable with restrictions (Klimisch 2) as it was not conducted according to guideline, however the study is scientifically acceptable with minor limitations in experimental design and reporting (e.g. number of replicates).