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In assessing the aquatic toxicity of strontium 2-ethylhexanoate, read-across to the assessment entities soluble strontium substances and 2-ethylhexanoic acid is applied since the ions of strontium 2-ethylhexanoate determine its aquatic toxicity.

Strontium

Reliable aquatic toxicity data of strontium ions and strontium substances are available from GLP-conform guideline studies covering three trophic levels (algae, daphnia, fish) and microorganisms.

Acute aquatic toxicity:

- An unbounded 72-h ErC50 value of > 47.1 mg Sr/L was identified for the growth rate of algae (Pseudokirchneriella subcapitata)

- An unbounded value of > 56.3 mg Sr/L and a bounded acute value of 125 mg Sr/L were identified for the freshwater invertebrate species Daphnia magna with the latter being well above the OECD test limit.

- An unbounded value of > 56.34 mg Sr/L was identified for the freshwater fish species Danio rerio

- An unbounded value of > 92.8 mg Sr/L (96h-LC50) was identified for the saltwater fish species Morone saxatilis

- An unbounded value of > 163.8 mg Sr/L (3 -h EC10) was derived for microorganisms (activated sludge)

Chronic aquatic toxicity is available for two trophic levels: algae and invertebrates.

- An ErC10 value of 24.3 mg Sr/L was identified for the growth rate of algae (Pseudokirchneriella subcapitata)

- A chronic value of 21 mg Sr/L is available for the invertebrate Daphnia magna.

2-ethylhexanoic acid

Acute data are available from studies for three trophic levels: algae, invertebrates and fish

- a 72-h ErC50 of 49.3 mg/L was identified for the algae Desmodesmus subspicatus (acc. To DIN 38412 part 9)

- a 48-h EC50 of 85.4 mg/L represents the lowest value identified for the invertebrate species Daphnia magna

- an unbounded value of > 100 mg/L (96-h LC50) was identified for the freshwater fish species Oryzias latipes based on data of an analogous substance (sodium 2-ethylhexanoate). Further studies of 2-ethylhexanoate with the freshwater fish species Oncorhynchus mykiss, Lepomis gibbosus and Leuciscus idus resulted in 96-h LC50 values > 100 mg/L

In sum, 2-ethylhexanoic acid has a low potential for acute aquatic toxicity.

Chronic data are available from studies for algae, aquatic invertebrates and microorganisms:

- a 72-h EC10 of 32.0 mg/L was identified for the green algae Desmodesmus subspicatus (acc. To DIN 38412 part 9)

- 21-d NOEC values of 18 mg/L and of 25.0 mg/L were identified for Daphnia magna.

- a 17-h EC10 of 71.7 mg/L was identified for the inhibition of bacterial growth (Pseudomonas putida)

In sum, 2-ethylhexanoic acid has a very low potential for chronic aquatic toxicity to algae and invertebrates and appears to be of low toxicity to microorganisms.

Strontium 2-ethylhexanoate

Using existing aquatic toxicity data of the dissociation products of strontium 2-ethylhexanoate, the aquatic hazard assessment is based on the most toxic moiety, i.e. 2-ethylhexanoate. Existing aquatic toxicity data of both 2-ethylhexanoate and strontium are recalculated for strontium 2-ethylhexanoate based on the respective maximum fraction of 81 % (w/w) 2-ethylhexanoate.

Regarding acute (short-term) toxicity, strontium has a low potential. Existing acute (short-term) aquatic toxicity data of 2-ethylhexanoate are recalculated for strontium 2-ethylhexanoate based on a maximum 2-ethylhexanoate content of 81%:

- a 72-h ErC50 of 60.9 mg/L was identified for the algae Desmodesmus subspicatus

- a 48-h EC50 of 105.4 mg/L represents the lowest value identified for the invertebrate species Daphnia magna

- an unbounded value of > 123.5 mg/L (96-h LC50) was identified for the freshwater fish species Oryzias latipes. Further studies with the freshwater fish species Oncorhynchus mykiss, Lepomis gibbosus and Leuciscus idus result in 96-h LC50 values > 123.5 mg/L

In sum, strontium 2-ethylhexanoate has a low potential for acute aquatic toxicity.

Regarding chronic (long-term) toxicity, strontium has a very low potential. Existing aquatic toxicity data of 2-ethylhexanoate are recalculated for strontium 2-ethylhexanoate based on a maximum 2-ethylhexanoate content of 81 %:

- a 72-h EC10 of 39.5 mg/L was identified for the green algae Desmodesmus subspicatus

- identified 21-d NOECs for Daphnia magna range from 22.2 mg/L to 30.9 mg/L

- a 17-h EC10 of 88.5 mg/L was identified for inhibition of bacterial growth (Pseudomonas putida)

In sum, strontium 2-ethylhexanoat has a very low potential for chronic aquatic toxicity to algae and invertebrates and appears to be of low toxicity to microorganisms.

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