Neodecanoic acid, zirconium salt

Endpoint summary

Description of key information

Aquatic toxicity studies of neodecanoic acid, zirconium salt are not available. Read-across to the assessment entities zirconium substances and neodecanoic acid is applied since the ions of neodecanoic acid, zirconium salt determine its fate and toxicity in the environment. Zirconium is poorly soluble and precipitates under most environmental conditions whereas neodecanoate is rather mobile.

 

Zirconium:

Reliable acute data are available from OECD and EU-guideline studies for three trophic level algae, invertebrates and fish indicating that acute effect concentrations are above corresponding OECD test limits:

• 96h-LL50 > 100 mg/L, OECD 203 test with zirconium dioxide and freshwater fish Dario rerio


• 48h-EC50 > 100 mg/L, acute static test according to EU method C2 with zirconium dioxide and Daphnia magna


• 72h- NOErL (growth rate) = 32 mg/L, 72h- EL50 > 100 mg/L; OECD 201 test with zirconium dioxide and Scenedesmus subspicatus. Inhibition of growth may be explained (at least in parts) with the measured phosphate depletion.


• Microorganisms in the STP will not be exposed to Zr, as it will either be removed in the primary settling tank before reaching the microorganisms, or it will not be bioavailable due to complexation. A standard activated sludge respiration inhibition study was still performed with zirconium acetate. No statistically significant toxic effects were observed at all test concentrations employed. The 3-h EC50 and NOEC were determined to be > 1000 mg/L and >= 1000 mg/L anhydrous zirconium acetate, respectively.

 

Neodecanoate:

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 > 1000 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

• 14-d NOEC of 2.22 mg/L neodecanoic acid for growth of Oncorhynchus mykiss; Chronic Value (ChV) of 1.5 mg/L (QSAR-based estimate) for fish, equivalent to a NOEC value of 1.1 mg/L.


• A 7-day chronic NOEC value of 3.4 mg/L for reproduction of Ceriodaphnia dubia

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 ≥ 100 mg/L for the inhibition of nitrification by microorganisms (Nitrosomonas sp.) is available.

 

Neodecanoic acid, zirconium salts:

Acute (short-term) toxicity: EC/LC50 values of zirconium and of neodecanoate are above the OECD test limit of 100 mg/L for short-.term toxicity tests. Thus, the potential for acute toxicity of neodecanoic acid, zirconium salts is expected to be low.

 

Long-term toxicity:

The potential of chronic toxicity of neodecanoic acid, zirconium salts is expected to be low based on the following:

• no acute toxicity to algae, crustacea and fish up to the OECD test limit of 100 mg/L for short-term toxicity tests


• Zirconium is poorly soluble and precipitates under most environmental conditions


• available chronic EC for zirconium, i.e. the 72h- NOErL (growth rate of algae) = 32 mg/L, is above the OECD test limit of 10 mg/L for chronic toxicity tests


• available chronic (equivalent) EC for neodecanoate for three trophic levels are at least above 1 mg/L.

In sum, based on read-across of toxicity data available for zirconium and neodecanoate, neodecanoic acid, zirconium salts does not meet aquatic hazard criteria of Regulation (EC) No 1272/2008 and its subsequent adaptation.