Calcium neodecanoate

Endpoint summary

Description of key information

In the assessment of calcium neodecanoate, read-across to the assessment entities soluble calcium substances and neodecanoic acid is applied since the ions of calcium neodecanoate determine its fate and toxicity in the environment.

 

Calcium

As an essential element for living organisms calcium has a very low potential for toxicity to freshwater as well as saltwater organisms. However, experimental toxicity data are available for several species, although exceeding corresponding OECD test limits:

- 96h-LC50 values of 1670.2, > 579.4 and > 1785.4 mg calcium /L were determined depending on the calcium salt used for the freshwater fish Pimephales promelas.

- 48h-LC50 values of 4410 and 4610 mg calcium/L were determined for saltwater fish species C. variegatus and M. beryllina, respectively.

- lowest 48-h LC50 of 561.7 (C. dubia) and 1100.0 mg calcium/L (M. bahia) were observed for fresh- and saltwater species, respectively (hydrated lime (CaOH2) studies without pH adaption excluded)

- an unbounded value of > 100 mg calcium/L can at least be expected for activated sludge microorganisms

- the lowest 96h- EC50 for green algae P subcapitata amounted to 100.2 mg/L calcium and a 7d - EC50 of 1162.3 mg Ca/L was obtained for aquatic macrophyte Lemna minor

 

In sum, calcium has very low potential for acute aquatic toxicity.

 

Neodecanoic acid

Reliable acute data are available from GLP-conform guideline studies for three trophic levels: algae, invertebrates and fish

- an unbounded value of > 100 mg/L (96h-LL50) was identified for rainbow trout

- an unbounded value of > 457 mg/L (48h-EL50) was identified for the invertebrate species Daphnia magna

- an unbounded value of > 100 mg/L (72h-LL50) was identified for the algae Pseudokirchneriella subcapitata

 

Reliable chronic data are available from GLP-conform guideline studies for two trophic levels: invertebrates and fish

- 21-d NOEC of 4.78 mg/L neoheptanoic acid (structural analogue) for reproduction of D. magna; Chronic Value (ChV) of 1.7 mg/L (QSAR-based estimate) for daphnids

- 14-d NOEC of 2.22 mg/L neodecanoic acid for growth of Oncorrhynchus mykiss; Chronic Value (ChV) of 1.6 mg/L (QSAR-based estimate) for fish

-Regarding algae, an EC10 or NOEC is not available for neodecanoate. However, based on the fact that the EC50 for growth rate of algae is > 100 mg/L, we may assume that it is unlikely that the EC10/NOEC < 1 mg/L. According to the QSAR-based outcome of the model ECOSAR v.2.0, neodecanoic acid has a very low potential for chronic toxicity to green algae since the chronic value (ChV = 10^([log (LOEC x NOEC)]/2)) of 12.3 mg/L is >> 1 mg/L.

Regarding the toxicity to aquatic microorganisms, a 4-h NOEC of ≥ 200 mg/L for the inhibition of nitrification by microorganisms (Nitrosomonas sp.) is available.

In sum, neodecanoic acid has very low potential for acute aquatic toxicity and a low potential for chronic toxicity.

 

Calcium neodecanoate

According to aquatic toxicity data of the dissociation products of calcium neodecanoate, the aquatic hazard assessment is based on the most toxic moiety.

 

Regarding acute (short-term) toxicity, the potential is low since relevant EC/LC50 values of calcium ions and of neodecanoate are above respective OECD test limits.

 

Regarding chronic (long-term) toxicity, calcium has very low potential. Existing aquatic toxicity data of neodecanoic acid and neoheptanoic acid are recalculated for calcium neodecanoate based on a maximum neodecanoate content of 90.6 %.

 

- 21-d NOEC of 5.28 mg/L for reproduction of D. magna; Chronic Value (ChV) of 1.88 mg/L (QSAR-based estimate) for daphnids

- 14-d NOEC of 2.45 mg/L for growth of Oncorrhynchus mykiss; Chronic Value (ChV) of 1.77 mg/L (QSAR-based estimate) for fish

Further, a 4-h NOEC > 220 mg/L for the inhibition of nitrification points to a very low potential for toxicity to sewage sludge microorganisms.