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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
Principles of method if other than guideline:
The steady state bioaccumulation factor of aluminium in brook trout Salvenlinus fontinalis was determined under flow-through conditions at a fixed nominal concentration of 200 µg/L aluminium and at pH 5.3, 6.1 and 7.2.
GLP compliance:
no
Specific details on test material used for the study:
See test material information
Radiolabelling:
no
Details on sampling:
- Sampling intervals/frequency for test organisms: Five fish from each treatment collected on days 0, 3, 7, 14, 28 and 56 during exposure and duplicate or triplicate fish samples collected on days 3, 7, 14 and 28 during depuration.
- Sampling intervals/frequency for test medium samples: Sampled weekly during exposure period of 56 days.
- Sample storage conditions before analysis: Fish weighed and then frozen for later analysis. Test medium collected in 100 mL polyethylene bottle , acidified with nitric acid to a final concentration of 1% (v/v).
- Details on sampling and analysis of test organisms and test media samples (e.g. sample preparation, analytical methods):
Test organism: Fish with wet weights less than 3.4 g were pooled, predigested overnight in a glass pressure tube 5 mL with sub-boiled nitric acid. The samples were then vortexed and the sealed tubes heated in a water bath at 70°C for 48 hours to digest the sample. The cooled sampled was then diluted to 100 mL with reverse osmois water to produce a final sample containing 5% nitric acid. Fish samples with wet weights greater than 3.4 g were lyophilized and then homogenized before being treated as above.
Test medium: 100 mL samples from each treatment were acidified with distilled reagent-grade nitric acid to a final concentration of 1% (v/v).
Vehicle:
no
Details on preparation of test solutions, spiked fish food or sediment:
PREPARATION OF SPIKED WATER
- Details of spiking: Proportional diluter delivered appropriate amounts of aluminiium sulphate stock solution and acid (1/3 nitric acid and 2/3 sulphuric acid) to glass aquaria (length 52 cm x width 32 cm x height 30.5 cm) equipped with 20.5 cm standpipes and containing 34.1 litres of solution. The diluter delivered one litre of exposure water to each aquarium every 15 minutes (2.8 volume replacement per day).
- Controls: Test medium only (fish analysed at day 0 only).
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): Not applicable
Test organisms (species):
Salvelinus fontinalis
Details on test organisms:
TEST ORGANISM
- Common name: Brook trout
- Source: Eyed eggs obtained from Beity's Resort, Valley, Washington.
- Age at study initiation: 30 days
- Length at study initiation: Not reported
- Weight at study initiation: 0.2 g
- Weight at termination: 0.24 to 1.50 g
- Method of breeding: Fish cultured from eyed eggs in well water (alkalinity 250 mg/L and hardness 270 mg/L as CaCO3) at 17 to 18ºC until they were about 30 days old.
- Health status: Not reported
- Description of housing/holding area: Glass aquaria (length 52 cm x width 32 cm x height 30.5 cm)
- Feeding during test: Yes
- Food type: Rangen commercial feed
- Amount: Ad libitum
- Frequency: Twice daily

ACCLIMATION
- Acclimation period: Three days
- Acclimation conditions (same as test or not): Yes
- Type and amount of food: Not reported
- Feeding frequency: Not reported
- Health during acclimation (any mortality observed): Not reported
Route of exposure:
aqueous
Test type:
flow-through
Water / sediment media type:
natural water: freshwater
Total exposure / uptake duration:
56 d
Total depuration duration:
28 d
Hardness:
Alkalinity 236-244 µeq/L
Test temperature:
12 ºC
pH:
Treatment 1: 5.3 (SD = 0.5)
Treatment 2: 6.1 (SD = 0.3)
Trwtment 3: 7.2 (SD = 0.1)
Dissolved oxygen:
Not reported
TOC:
Not reported
Salinity:
Not applicable
Details on test conditions:
TEST SYSTEM
- Test vessel: Glass aquaria
- Type: Open
- Material, size, headspace, fill volume: Length 52 cm x width 32 cm x height 30.5 cm equipped with 20.5 cm standpipes and containing 34.1 litres of solution.
- Aeration: No details given
- Type of flow-through (e.g. peristaltic or proportional diluter): Proportional diluter
- Renewal rate of test solution (frequency/flow rate): One litre every 15 minutes (2.8 volume replacements per day)
- No. of organisms per vessel: 100 (at start)
- No. of vessels per concentration (replicates): 2
- No. of vessels per control / vehicle control (replicates): None

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Well water
- Alkalinity: 236 - 244 µeq/L
- Holding medium different from test medium: Yes. See above
- Intervals of water quality measurement: pH measured daily
- Intervals of test medium replacement: Flow-throught system. 2.8 volume replacements per day.

OTHER TEST CONDITIONS
- Adjustment of pH: Yes by proportional controller using nitric (1/3) and sulphuric (2/3) acid mixtures.
- Photoperiod: Not reported
- Light intensity: Not reorted
Nominal and measured concentrations:
Nominal concentration 200 µg/L at nominally three pH's 5.3, 6.1 and 7.2.
Measured values: Treatment 1: 251.5 to 198.1 µg/L at nominal pH 5.3. Treatment 2: 323.5 to 211.9 µg/L at nominal pH 6.1. Treatment 3: 415.0 to 253.6 µg/L at nominal pH 7.2.
Reference substance (positive control):
no
Details on estimation of bioconcentration:
The BIOFAC computer program of Blau and Agin was used to derive uptake and clearance rate constants, biological half-lives, bioconcentration factors (BCF) and the time to 90% steady state for aluminium in whole-body tissues.

Reference: Blau GE, Agin GL (1978). A user's manual for BIOFAC: A computer program for characterizing the rate of uptake and clearance of chemicals in aquatic organisms. Central research, physical research and math applications. The Dow Chemical Company, Midland, MI, USA.
Type:
BCF
Value:
215 dimensionless
Basis:
whole body w.w.
Calculation basis:
steady state
Remarks on result:
other: Optimal estimated value at pH 5.3. Linearized standard deviation 90.
Remarks:
Conc.in environment / dose:200 µg/L aluminium
Type:
BCF
Value:
123 dimensionless
Basis:
whole body w.w.
Calculation basis:
steady state
Remarks on result:
other: Optimal estimated value at pH 6.1. Linearized standard deviation 54.
Remarks:
Conc.in environment / dose:200 µg/L aluminium
Key result
Type:
BCF
Value:
36 dimensionless
Basis:
whole body w.w.
Calculation basis:
steady state
Remarks on result:
other: Optimal estimated value at pH 7.2. Linearized standard deviation 20.
Remarks:
Conc.in environment / dose:200 µg/L aluminium
Elimination:
yes
Parameter:
DT50
Depuration time (DT):
0.46 d
Elimination:
yes
Parameter:
DT50
Depuration time (DT):
1.26 d
Key result
Elimination:
yes
Parameter:
DT50
Depuration time (DT):
0.52 d
Details on kinetic parameters:
- Uptake rate constant (k1): 352 (SD = 102)/d at pH 5.3, 68 (SD = 21)/d at pH 6.1 and 49 (SD = 20) at pH 7.2.
- Depuration (loss) rate constant (k2): 1.5 (SD = 0.41)/d at pH 5.3, 55 (SD = 0.17)/d at pH 6.1 and 1.34 (SD = 0.50) at pH 7.2.
- Biological half-life: 0.46 (SD = 0.12) days at pH 5.3: 1; 1.26 (SD = 0.39) days at pH 6.1; and 0.52 (SD = 0.19) at pH 7.2.
- Days to 90% steady state: 1.53 (SD = 0.42) days at pH 5.3, 4.17 (SD = 1.31) days at pH 6.1 and 1.72 (SD = 0.64) days at pH 7.2.
Metabolites:
No data
Results with reference substance (positive control):
Not applicable
Details on results:
- Mortality of test organisms: At pH 5.3: 2.0 % (day 3), 11.5 % (day 7), 21.0 % (day 14), 42.5 % (day 28) and 73.0 % (day 56). At pH 6.1: 0.0 % (day 3), 0.0 % (day 7), 3.5 % (day 14), 27.5 % (day 28) and 48.0 % (day 56). At pH 7.2: 0.0 % (day 3), 0.0 % (day 7), 0.0 % (day 14), 0.0 % (day 28) and 1.0 % (day 56).
- Observations on body length and weight: The weight of fish exposed to aluminium at pHs 5.3 and 6.1 did not differ significantly throughout the exposure periods. Except for day 3, all fish exposed to aluminium at pH 7.2 had significantly higher weights than the fish exposed to the lower pHs.
Reported statistics:
ANOVA was used to statistically analyse percentage mortality (arcsine transformed values), fish weight and whole-body residues of aluminium. Least significant difference (LSD) tests were used to determine significant differences between paramater means. The two-compartment model of Blau et al (Blau GE, Neely WB, Branson DR (1975). Ecokinetics: A study of the fate and distribution of chemicals in laboratory ecosystems. Am. Inst. Chem. Eng. J. 21: 854-861) was used to determine the residue dynamics of aluminium in whole-body tissues at each test treatment.
Mortality measured daily.

During the exposure the measured pHs were close to the nominal values. The measured concentrations were initially higher than the nominal value (200 µg/L aluminium) but gradually approached the expected value.

Background concentrations of aluminium average 0.68 µg/g for fish from the laboratory culture. Aluminium concentrations in fish during exposure ranged from 2.8 to 78 µg/g and during depuration ranged from 0.7 to 5.3 µg/g

The maximum observed BCF were 232 at pH 5.3, 153 at pH 6.1 and 46 at pH 7.2. The results clearly show that aluminium uptake and absorption by brook trout decreases markedly at higher pHs.

During the depuration period all fish eliminated aluminium very quickly and by day 3 all fish contained less than 5 µg/g.

Mortality was significantly higher for fish exposed to aluminium at pH 5.3, except at day 56 when mortality at pHs 5.3 and 6.1 were not significantly different. Mortality of brook trout exposed to aluminium at pH 7. was less than 3 %.

Validity criteria fulfilled:
not applicable
Conclusions:
The bioconcentration factor of aluminium in the fish species, Salvelinus fontinalis is 215 at pH 5.3, 123 at pH 6.1 and 36 at pH 7.2.
Executive summary:

The bioconcentration factor of aluminium in the fish species,Salvelinus fontinalis is 215 at pH 5.3, 123 at pH 6.1 and 36 at pH 7.2.The bioconcentration factor was determined in a non-GLP, non-guideline study published in a peer-reviewed journal (Cleveland et al 1991).The study measured the uptake of aluminium in Salvelinus fontinalis under flow-through conditions at a fixed nominal concentration of 200 µg/L aluminium and at three pHs, 5.3, 6.1 and 7.2.There are limitations in design and/or reporting but the study follows sound scientific principles and is considered reliable and relevant for use for this endpoint.

Description of key information

Aluminium is expected to have a low potential for bioaccumulation, with BCF of around 36 at pH 7.2, and the fatty acids are natural substances with a long history of safe use in foods. In realistic use scenarios, the aluminium thickener will be contained in base oil, with the formulated greases specifically designed to minimise the leaching of the thickener. Therefore, the substance is not expected to bioaccumulate in the aquatic environment.

Key value for chemical safety assessment

BCF (aquatic species):
36 dimensionless

Additional information

No data are available on the bioaccumulation of the substance in aquatic species. The dissociation of the substance in the aquatic environment would result in hydrated aluminium oxide species and fatty acids. The fatty acids used for the formation of the substance are either natural substances or chemically indistinguishable from natural substances. The fatty acid components of the substance are considered to be non-hazardous. Fatty acids of natural origin have a long history of safe use in foods and, under the REACH regulation Annex V, natural C6 to C24 fatty acids are exempt from registration. In addition, fatty acids in the range C16-18 are considered to be readily biodegradable based on the data presented in this dossier, and therefore, bioaccumulation data are presented here for the aluminium component only.

Cleveland et al (1991) determined the steady state bioaccumulation factor of aluminium in brook trout Salvenlinus fontinalis. The flow-through experimental procedure followed sound scientific principles and is considered reliable and suitable for use for this endpoint. The fish were exposed to a steady state nominal aluminium concentration of 200 µg/L for 56 days followed by a 28 day depuration period. Duplicate studies were run at nominal pH of 5.3, 6.1 and 7.2. The whole fish estimated steady state BCF, which were inversely related to pH, was 215 at pH 5.3, 123 at pH 6.1 and 36 at pH 7.2. The estimated time to 90% steady state was 1.5 days at pH 5.3, 4.2 days at pH 6.1 and 1.7 days at pH 7.2. The fish eliminated aluminium rapidly with biological half-life of 0.46 days at pH 5.3, 1.26 days at pH 6.1 and 0.52 days at pH 7.2.

The availability of aluminium in the aqueous environment is very dependent on pH. Soluble aluminium species are only readily available to aquatic species at pH < 4. At neutral pH, aluminium will be in the form of essentially insoluble hydrated oxide species, which reduces their bioavailability by direct uptake from water. Since the fatty acid components are considered not to bioaccumulate in the aquatic environment, the substance is not expected to pose a risk of secondary poisoning. Furthermore, in realistic use scenarios, the aluminium thickener will be contained in base oil, with the formulated greases specifically designed to minimise the leaching of the thickener. Therefore, during use, the concentrations of the substance which would be bioavailable are further limited.