(3E)-1,7,7-trimethyl-3-(4-methylbenzylidene)bicyclo[2.2.1]heptan-2-one

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

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).