Fatty acids, C6-19-branched, calcium salts

Endpoint summary

Description of key information

In the assessment of fatty acids, C6-19-branched, calcium salts, read-across to the assessment entities soluble calcium substances and C6-19-branched fatty acids (or rather its structural analogue neodecanoic acid) is applied since the ions of calcium fatty acids, C6-19-branched, calcium salts 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 (structural analogue of C6-19-branched fatty acids)

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 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.

 

Fatty acids, C6-19-branched, calcium salts

Using existing aquatic toxicity data of the dissociation products of fatty acids, C6-19-branched, calcium salts (i.e. calcium and C6-19-branched fatty acids, represented by read-across to the structural analogue neodecanoic acid) 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 C6-19-branched fatty acids (or rather its structural analogue neodecanoic acid) 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 (structural analogues of C6-19-branched fatty acids) are recalculated for fatty acids, C6-19-branched, calcium salts based on a maximum C6-19-branched fatty acid content of 94.6 %.

 

- 14-d NOEC of 2.35 mg/L for growth of Oncorrhynchus mykiss; Chronic Value (ChV) of 1.69 mg/L (QSAR-based estimate) for fish

- 21-d NOEC of 5.05 mg/L for reproduction of D. magna; Chronic Value (ChV) of 1.80 mg/L (QSAR-based estimate) for daphnids

Further, a 4-h NOEC > 211 mg/L for the inhibition of nitrification points to a very low potential for toxicity to sewage sludge microorganisms.