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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:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
No guidance study. Ba-levels were measured in field-collected fish at different locations. Relevant study for natural field conditions. Bioaccumulation factors calculated using Ba concentrations in unfiltered water.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Bluegills and filtered water were sampled from the field and analysed for several elements, among which barium.
GLP compliance:
not specified
Details on sampling:
- Sampling intervals/frequency: Composite samples of filtered and unfiltered water from the Channel were collected, acidified in the field and frozen/refrigerated. Bluegills were collected from the Merced River and from the Salt Slough with a gas-powered electrofisher. Ten composite carcass and 10 composite gonad samples each from the Merced River and the Salt Slough were analysed. Each composite sample consisted of carcass or gonad samples either from 2 female bluegills or 3 male bluegills.
Test organisms (species):
Lepomis macrochirus
Route of exposure:
aqueous
Test type:
field study
Water / sediment media type:
natural water: freshwater
Hardness:
Merced river: 45.6-79.6 mg/L as CaCO3 (mean: 60.1 mg/L as CaCO3)
Salt Slough: 347.0-535.3 mg/L as CaCO3 (mean: 422.7 mg/L as CaCO3)
Test temperature:
Field temperature at time of collection: 15.2-24.1 degrees Celcius.
pH:
Merced River: 7.25-7.57 (mean: 7.40)
Salt Slough: 7.58-7.92 (mean: 7.72)
Nominal and measured concentrations:
Merced river: filtered: 0.034 µg/mL
Merced river: unfiltered: 0.043 µg/mL
Salt Slough: filtered: 0.065 µg/mL
Salt Slough: unfiltered: 0.101 µg/mL
Type:
BCF
Value:
68.4 L/kg
Basis:
other: wet weight of bluegill tissue (carcass)
Remarks on result:
other: female bluegill in River Merced (range: 37.6-98.8)
Remarks:
Conc.in environment / dose:0.034 mg/L
Type:
BCF
Value:
6.4 L/kg
Basis:
other: wet weight of bluegill tissue (gonad)
Remarks on result:
other: female bluegill in River Merced (range: 4.2-11.5)
Remarks:
Conc.in environment / dose:0.034 mg/L
Type:
BCF
Value:
74.4 L/kg
Basis:
other: wet weight of bluegill tissue (carcass)
Remarks on result:
other: male bluegill in River Merced (range: 54.0-92.7)
Remarks:
Conc.in environment / dose:0.034 mg/L
Type:
BCF
Value:
22.8 L/kg
Basis:
other: wet weight of bluegill tissue (carcass)
Remarks on result:
other: female bluegill in Salt Slough (range: 18.6-30.6)
Remarks:
Conc.in environment / dose:0.065 mg/L
Type:
BCF
Value:
1.2 L/kg
Basis:
other: wet weight of bluegill tissue (gonad)
Remarks on result:
other: female bluegill in Salt Slough (range: 0.7-2.2)
Remarks:
Conc.in environment / dose:0.065 mg/L
Type:
BCF
Value:
20.2 L/kg
Basis:
other: wet weight of bluegill tissue (carcass)
Remarks on result:
other: male bluegill in Salt Slough (range: 15.5-33.3)
Remarks:
Conc.in environment / dose:0.065 mg/L
Reported statistics:
Analysis of variance, t-tests, and Spearman's rank correlation tests were used to determine significant differences at p <= 0.05.
Validity criteria fulfilled:
not specified
Conclusions:
Reported bioconcentration values can be used in a weight of evidence approach for the evaluation of Ba bioaccumulation in the aquatic environment.
The highest mean bioaccumulation factor obtained was 74.4 L/kg, indicating the low potential of Ba for bioaccumulation.

Description of key information

Bioconcentration values reported by Nakamoto and Hassler (1992) for bluegills catched in the field can be used for the evaluation of barium bioaccumulation in the aquatic environment. Barium does not seem to accumulate further in the aquatic foodchain, as was clear from the results of this field study. Bioconcentation factors from 15.5 to 98.8 L/kg ww were reported for carcass and from 0.7 to 64.8 L/kg ww for female gonads. Because these values were calculated using barium concentrations in unfiltered water, and barium concentrations in filtered water were lower than those in unfiltered water, it was decided to use the highest mean bioaccumulation factor reported by this study, i.e., 74.4 L/kg ww, for use in case exposure calculations are needed for secondary poisoning (aquatic foodchain) or for exposure of man via the environment. 

Key value for chemical safety assessment

BCF (aquatic species):
74.4 L/kg ww

Additional information

Only one study was identified as containing relevant and reliable information on this endpoint. In this key study from Nakamoto and Hassler (1992), the effects of water quality and exposure to trace elements in irrigation return flows on bluegills (Lepomis macrochirus) were studied in the Merced River and Salt Slough, tributaries to the San Joaquin River, California. The mean concentrations of barium were significantly lower in filtered than in unfiltered water.

The concentrations of barium were below levels that have significant adverse chronic effects on bluegills. Reported bioaccumulation values were calculated using barium concentrations in carcass and gonads on the one hand and barium concentrations in unfiltered water on the other hand (which may lead to somewhat lower bioaccumulation factors). Therefore, it is advised to use the highest mean reported bioaccumulation factor as key value, which is 74.4 L/kg ww. The reported values indicate that barium has a low potential for bioaccumulation in the aquatic foodchain.