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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:
other: Non-guideline, non-standard guideline, but acceptable method, Ag concentration measured through out the study.
Principles of method if other than guideline:
An investigation of 110mAg accumulation over a 6 week period followed by a depuration period.
GLP compliance:
not specified
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Not applicable
Radiolabelling:
yes
Details on sampling:
Radioactivity of the water measured several times a week. 110mAg uptake kinetics followed by radioactivity measurements in 10-20 randomly selected individuals. In depuration period all individuals were monitored for 110mAg. Tissue distribution of the residual radionuclide measured after 42 days depuration.
Vehicle:
no
Details on preparation of test solutions, spiked fish food or sediment:
The 110mAgCN solution was held in dissolved form in 0.1 N NH4OH. The water labelled with 30 Bq/mL of 110mAg was completely renewed three times a week. 110mAg specific activity was 7.2x104 Bq/µg Ag.
Test organisms (species):
Cyprinus carpio
Details on test organisms:
20 individuals, 6 months old, mean initial body mass of 1.46g (SD 0.10)
Route of exposure:
aqueous
Test type:
not specified
Water / sediment media type:
not specified
Remarks:
freshwater
Total exposure / uptake duration:
41 d
Total depuration duration:
42 d
Hardness:
No data reported
Test temperature:
20±1°C
pH:
No data reported
Dissolved oxygen:
No data reported
TOC:
No data reported
Salinity:
Not applicable
Details on test conditions:
5L aquarium, aerated, animals fed 5 days out of 7 with non-radioactive field captured midge larvae.
Nominal and measured concentrations:
No data reported
Reference substance (positive control):
not specified
Details on estimation of bioconcentration:
No data reported
Type:
BCF
Value:
70 dimensionless
Basis:
whole body w.w.
Time of plateau:
30 d
Calculation basis:
steady state
Remarks on result:
other: Conc.in environment / dose:0.14-0.28 ppb
Details on kinetic parameters:
Steady state achieved after ~30d, exposure concentration approximately 0.14 to 0.28 ppb, BCF ~70 at steady state.
Metabolites:
No data reported
Results with reference substance (positive control):
Not applicable
Details on results:
The maximum 110mAg concentration factor was extrapolated to be 106 and would be reached after 180 days. The liver showed the highest 110mAg concentration factor at the end of the exposure phase.
Reported statistics:
No data reported
Validity criteria fulfilled:
not applicable
Conclusions:
The reported BCF at a steady state was ~70.
Executive summary:

The reported BCF at a steady state was ~70. This study does not follow a standard guideline and only tests one concentration. However, the method is acceptable and therefore this study is considered suitable for use for this endpoint.

Description of key information

A BCF of 70 for Cyprinus carpio based on wet weight of whole fish is selected as the key study.

Key value for chemical safety assessment

BCF (aquatic species):
70 dimensionless

Additional information

Bioaccumulation in aquatic organisms: Bioaccumulation in fish

Several studies report the bioaccumulation potential of silver in fish after exposure to ionic silver. The key study selected for this endpoint is Baudin et al. (1993) in which carp were exposed to approximately 0.2 µg Ag/L for a six-week period. A steady state concentration in fish was achieved after 30 days and a BCF value of 70 was calculated for the whole fish on a wet weight basis. Various other bioaccumulation studies in fish are available, including Garnier et al. (1990), Webb et al. (2002), Galvez et al. (2002), Scown et al. (2010) and Zarco-Fernandez et al. (2018).

Galvez (2002) exposed juvenile rainbow trout Oncorhynchus mykiss to a two day radioactive pulse of 110mAg at 11.9 µg/L followed by a 19 day post-tracer exposure to non-radioactive Ag(l). A whole body BCF of 2.5 was reported after days one and eight. Garnier et al. (1990) reported a whole body BCF of 2.7 for brown trout Salmo trutta fingerlings over 57 days. In both studies, the greatest accumulation was observed in the liver.

Webb et al. (2000) report BCF for a range of marine species based on studies employing OECD guideline 305. The data available for most of the species was not fully reported and did not provide sufficient information for assessment. The steady state BCF for silver in the liver of Oligocuttus maculosus was calculated using data presented within the study to be 9.2 - 15.1 L/Kg at a salinity of 30 ppt (normal seawater) and 44.3 to 79.4 L/Kg at a salinity of 18 ppt.

Bioaccumulation in aquatic organisms: Bioaccumulation in aquatic invertebrates

Whilst bioaccumulation in fish drives the assessment of bioaccumulation under REACH, several studies that describe the relative bioaccumulation potential of silver from ionic silver exposures in aquatic invertebrates are available.

According to the CLP guidance, high-quality data on the BCF value for invertebrate species may be used if there is no BCF value for fish species. An invertebrate (mussel, oyster or scallop) BCF can be used as a worst-case (conservative) value for fish, while BCF for algae should not be used (ECHA, 2017). Reliable bioaccumulation data are available for bivalves, crustaceans, gastropods and one echinoderm species, showing a wide range in bioaccumulation factors (2.5 to 27500 L/kg ww). There is no clear trend in the data:

- BCF values above 500 L/kg ww are only observed for Daphnia magna (1520-3600 L/kg ww), the marine bivalve Gafrarium tumidum (±7500 L/kg ww) and freshwater and marine gastropod species (570-27500 L/kg ww).

- results for 2 freshwater and 2 marine bivalves, marine crustacea and the echinoderm Paracentrotus lividus all show BCF values below 500 L/kg ww.