Calcium di(octanoate)

Endpoint summary

Description of key information

Aquatic toxicity endpoints are completed based on test data following standard guidelines. All data are therefore considered to be reliable and relevant for the endpoint concerned.

 

Short-term toxicity to Fish

A Quantitative Structure Activity Realtionship (QSAR) model was used to calculate the acute toxicity to fish exposed to the test item. This QSAR model has been validated to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004) and predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following the Guideline for Testing of Chemicals No. 203, "Fish Acute Toxicity Test"(OECD, 2019), referenced as Method C.1 of Commission Regulation No. 440/2008(European Commission, 2008). The criterion predicted was the LC₅₀ (Median Lethal Concentration), a statistically derived concentration which is expected to cause mortality in 50% of test animals within a period of 96 hours.

Since the test item is an organic salt which dissociates into aqueous solute, only the carboxylate (i.e. octanoate) has been considered for the prediction. Indeed in experimental tests for organic salts, the concentration of the counter-ion is usually not measured and only the organic ion (or its neutral form) is monitored. Moreover the medium used to conduct ecotoxicological assays is buffered at pH between 6 – 9 where there is an equilibrium between nonionized form (free acid) and ionised form (carboxylate), and both are present in the test medium, no matter if at first

the acid or a salt of it was introduced. In fact, at this pH, most of the substance will be in its ionized form (carboxylate). Consequently, the toxicity of the test item predicted in this study is based on the octanoic acid.

The test item falls within the applicability domain of the model and can therefore be considered a reliable prediction for acute toxicity (96h-LC50) to fish. Therefore, this endpoint value can be considered valid for use in risk assessment and classification and labelling.

The 96h-LC50 of the test item to fish was predicted as 100 mg/L.

95% confidence interval (α = 0.05): 61 – 160 mg/L.

Short-term toxicity to aquatic invertebrates

The acute toxicity of the test item to Daphnia magna was determined in a static test following OECD guideline 202. Daphnia were exposed to nominal concentrations of 19.8, 29.6, 44.4, 66.7 and 100 mg test item/L, alongside a control. Based on nominal concentrations, the 48-hour EC50 was >100 mg test item/L. The 48-hour NOEC and LOEC were 100 mg test item/L and >100 mg test item/L, respectively. The study is a GLP compliant, guideline experimental study and is available as an unpublished study report. There are no restrictions and the study is fully adequate for assessment.

 

Toxicity to aquatic algae and cyanobacteria

The toxicity of the test item to the green algae Pseudokirchneriella subcapitata was determined in a study following OECD guideline 201. Algae were exposed to nominal concentrations of 0.763, 2.44, 7.81, 25.0 and 80.0 mg test item/L, equivalent to geometric mean measured concentrations of 0.107, 0.161, 0.456, 1.18 and 4.65 mg test item/L alongside a control. The 72-hour ErC50 and ErC10 were calculated to be 32.3 mg test item/L and 5.40 mg test item/L, respectively, based on nominal concentrations and 1.60 mg test item/L and 0.223 mg test item/L, respectively, based on geometric mean measured concentrations. The 72-hour EyC50 and EyC10 were calculated to be 4.08 mg test item/L and <0.763 mg test item/L, respectively, based on nominal concentrations and 0.280 mg test item/L and <0.107 mg test item/L, respectively, based on geometric mean measured concentrations. The study is a GLP compliant, guideline experimental study and is available as an unpublished report. There are no restrictions and it is fully adequate for assessment.

Toxicity to microorganisms

A study investigating the toxicity of the substance to Pseudomonas putida was conducted on octanoic acid. This cell multiplication inhibition test (1988) was conducted similarly to ISO 10712. The test organism was exposed to a wide range of nominal concentrations (0.266 - 1088.00 mg/L). The study determined an EC10 (18h) of 912 mg/L (nominal).