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EC number: 812-724-1
CAS number: 106705-37-7
Reliable acute aquatic toxicity data of strontium neodecanoate are available from GLP-conform guideline studies for algae, daphnia, fish and microorganisms. Respective EC/LC50 values are well above respective test limits of 100 mg/L, i.e., 96-h LC50 for fish (Danio rerio): >299.7 mg/L, 48-h EC50 for immobilisation of Daphnia magna: >299.7 mg/L, 72-h EC50 for algal growth rate (Pseudokirchneriella subcapitata): >250 mg/L, 3-h EC50 for the respiration inhibition of activated sludge: >871.3 mg/L. Therefore, strontium neodecanoate has a low potential for acute toxicity to aquatic organisms.
Reliable chronic aquatic toxicity data of strontium neodecanoate are available from GLP-conform guideline studies for algae and microorganisms. Respective EC10 values are well above 100 mg/L, i.e., 72-h EC10 for algal growth rate (Pseudokirchneriella subcapitata): 129 mg/L, 3-h EC10 for the respiration inhibition of activated sludge: >871.3 mg/L. Thus, strontium neodecanoate has a low potential for chronic toxicity to aquatic algae and microorganisms.
In sum, reported substance-specific L(E)C50 and chronic EC10 values of strontium neodecanoate are well above aquatic hazard criteria as summarised in the Table below. Based on read-across of acute and chronic toxicity data available for soluble strontium substances, strontium neodecanoate does also not meet aquatic hazard criteria.
Table: Acute and chronic aquatic toxicity data for strontium neodecanoate and its dissolved ions
3.4 mg/L (7-day NOEC for Ceriodaphnia dubia)
1.1 mg/L (based on 30-day Chronic Value predicted by QSAR)
Metal carboxylates are substances consisting of a metal and a carboxylic acid. Based on the solubility of strontium neodecanoate in water (8.47 g dissolved Sr/L at pH 8.4 corresponding to 45.07 g strontium neodecanoate/L), a complete dissociation of strontium neodecanoate resulting in strontium and neodecanoate ions may be assumed under environmental conditions. The respective dissociation is reversible and the ratio of the salt /dissociated ions is dependent on the metal-ligand dissociation constant of the salt, the composition of the solution and its pH.
A metal-ligand complexation constant of strontium neodecanoate could not be identified. Data for alkaline earth metals appear to be generally limited. However, alkaline earth metals tend to form complexes with ionic character as a result of their low electronegativity. Further, the ionic bonding of alkaline earth metals is typically described as resulting from electrostatic attractive forces between opposite charges, which increase with decreasing separation distance between ions. Based on an analysis by Carbonaro & Di Toro (2007) of monodentate binding of strontium to negatively-charged oxygen donor atoms, including carboxylic functional groups, monodentate ligands such as neodecanoate are not expected to bind strongly with strontium. Accordingly, protons will always out-compete strontium ions for complexation of monodentate ligands given equal activities of free strontium and hydrogen ions. The metal-ligand formation constants (log KML) of strontium with other carboxylic acids, i.e. acetic, propanoic and butanoic acid, ranging from 0.78 to 0.89, further point to a low strength of the monodentate bond between carboxyl groups and strontium.
The analysis by Carbonaro & Di Toro (2007) suggests that the following equation models monodentate binding to negatively-charged oxygen donor atoms of carboxylic functional groups:
log KML= αO* log KHL+ βO; where
KMLis the metal-ligand formation constant, KHLis the corresponding proton–ligand formation constant, and αOand βOare termed the Irving–Rossotti slope and intercept, respectively. Applying the equation and parameters derived by Carbonaro & Di Toro (2007) and the pKa of neodecanoic acid of 4.69 results in:
log KML= 0.160 * 4.69 + 0.069
log KML= 0.82 (estimated strontium-neodecanoate formation constant).
Thus, it may reasonably be assumed that based on the estimated strontium-neodecanoate formation constant, the respective behaviour of the dissociated strontium cations and neodecanoate anions in the environment determine the fate of strontium neodecanoate upon dissolution with regard to (bio)degradation, bioaccumulation, partitioning resulting in a different relative distribution in environmental compartments (water, air, sediment and soil) and subsequently its ecotoxicological potential.
Therefore, in the assessment of the ecotoxicity of strontium neodecanoate, read-across to neodecanoic acid (CAS 26896-20-8; EC 248-093-9) and soluble strontium substances is applied since the ions of strontium neodecanoate determine its ecotoxicological potential.
Carbonaro RF & Di Toro DM (2007) Linear free energy relationships for metal–ligand complexation: Monodentate binding to negatively-charged oxygen donor atoms. Geochimica et Cosmochimica Acta 71: 3958–3968.
neodecanoate dissolves and dissociates into
strontium and neodecanoate ions upon contact
with an aqueous medium.
Therefore, the aquatic hazard potential is assessed based on the
substance-specific toxicity data as well as toxicity data available for
strontium and neodecanoate.
Reliable acute aquatic toxicity data of
strontium neodecanoate are available from GLP-conform guideline studies
for algae, daphnia and fish; respective EC/LC50 values are well above
100 mg/L. Therefore, strontium neodecanoate does not meet classification
criteria as short-term hazard to the aquatic environment under
Regulation (EC) No 1272/2008 and subsequent adaptations.
Reliable chronic aquatic toxicity data of
strontium neodecanoate are available from GLP-conform guideline studie
for algae, the respective EC10 value is well above 100 mg/L. Chronic
fish and daphnia toxicity data are lacking for strontium neodecanoate.
However, chronic aquatic toxicity of strontium and neodecanoate to
daphnia as well as chronic toxicity of neodecanoate to fish is not
observed and/or estimated at or below 1 mg/L.
Solely, long-term toxicity to fish has not
been quantified sufficiently. Thus, adequate chronic toxicity data are
not available for one trophic level. Criteria given in Table 4.1.0(b)
iii) are applied in accordance with Figure 4.1.1 of Regulation (EC) No
1272/2008. The 96-h LC 50 for fish of strontium neodecanoate is > 299.7
mg/L and thus above the classification criteria for substances for which
adequate chronic toxicity data are not available. Therefore, strontium
neodecanoate does not meet classification criteria as long-term hazard
to the aquatic environment under Regulation (EC) No 1272/2008 and
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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