Strontium chloride

Bioaccumulation: aquatic / sediment

Description of key information

- Concentration factors of strontium in soft parts of fish (muscle, gonads) generally ranged between 0.2 and 91.9 (Moiseenko and Kudryavtseva, 2001; Nakamoto and Hassler, 1992; Ueda et al, 1973; Stanek et al, 1990); concentration factors for algae were situated between 0.3 and 115 (Ueda et al, 1973; Stanek et al, 1990). Lowest values were found for marine species, but the ambient concentration of Sr in marine water (8 mg/L) is markedly higher than levels in the freshwater compartment (μg-range).
- Higher concentration factors were found in hard body parts (bones, shell): values ranges between 10 and 14111 for fish bones and between 2 and 200 for shells of molluscs (Moiseenko and Kudryavtseva, 2001; Ueda et al, 1973; Stanek et al, 1990; Bologa, 1984)
- Concentration levels of Sr in soft tissues of fish (muscle, flesh, gonads & ovary, liver) were situated between 0.5 and 5.6 μg/g dry wt (Hellou et al, 1992a, 1992b; Moiseenko and Kudryavtseva, 2001; Nakamoto and Hassler, 1992; Ueda et al, 1973) ; Whole body concentrations (incl. bones) ranged from 18 to 450 μg/g (Nakamoto and Hassler, 1992; Hinck et al, 2008; Saiki and Palawski, 1990; Radtke et al, 1988; Schroeder et al, 1988; Allen et al, 2001); Levels in bones were found between 78 and 690 μg/g (Moiseenko and Kudryavtseva, 2001; Ueda et al, 1973).
- Moiseenko and Kudryavtseva (2001) noted for fish a decrease of the BAF with increasing Sr-concentration in the water (9, 16, 66 μg/L). These data support the hypothesis that fish are able to maintain a rather constant concentration of Sr in their body. A decrease of the muscle and skeleton BAF with increasing Sr-level in the water was also noted for the white fish, although data were only available for 2 concentration levels (66 and 16 μg/L).

Additional information

Read-across statement:

The speciation and chemistry of strontium is rather simple. As a reactive electropositive metal Sr is easily oxidized to the stable and colourlessSr²⁺ion in most of its compounds, the chemical behaviour resembling that of Ca and/or Ba (Wennig and Kirsch, 1988). In the environment, the element only occurs in one valence state (Sr²⁺), does not form strong organic or inorganic complexes and is commonly present in solution asSr²⁺(Lollar, 2005).

Consequently, the transport, fate, and toxicity of strontium in the environment are largely controlled by solubility of different Sr-salts (SrCO₃,Sr(NO₃)₂,SrSO₄,Sr(OH)₂…)

 

The derivation of environmental fate data like adsorption/desorption coefficients and bioconcentration/bioaccumulation factors is based on measured Sr-levels, and reflect the properties of the dissolved strontium cation. The latter form is the only form under which dissolved strontium originating from a simple inorganic Sr-compound will occur. Therefore the reported elemental-based environmental fate data in this section of the dossier are considered relevant for the behaviour of strontium that is released into the environment from strontium chloride.

The following information is taken into account for any hazard / risk / bioaccumulation assessment:

Data that were retrieved, suggest that strontium bioconcentration and bioaccumulation is negligible: internal concentrations of soft tissues remain situated between 0.5 and 5.7 μg/g, regardless of the external concentration (9 – 8000 μg/L). Whole body concentrations were considered less relevant due to the potential of Sr to replace Ca in the bones. Reported tissue BAFs vary more than 2 orders of magnitude, but remain below 100. Moreover, an inverse relationship between exposure concentration and BAF has been observed, i. e., decreasing BAFs with increasing Sr-levels in the water column (Moiseenko and Kudryavtseva, 2001).

The data indicate that Sr is homeostatically controlled by aquatic organisms. The homeostatic control in soft tissues of Sr is observed to continue to function up to the milligram range of exposure (8 mg/L in seawater; Ueda et al, 1973).

Limited information on transfer of Sr through the food chain indicates that strontium does not biomagnify in aquatic food chains.