Bismuth(3+) neodecanoate

Endpoint summary

Description of key information

In the assessment of bismuth (3+) neodecanoate, read-across to the assessment entities bismuth cations and neodecanoate anions is applied since the ions of bismuth (3+) neodecanoate determine its fate and toxicity in the environment.

 

Bismuth:

Bismuth has a very low potential for toxicity to aquatic organisms as indicated by acute effect concentrations that are above corresponding OECD test limits:

- a 96 -h LC50 of > 100 mg/L bismuth (WAF, 7d equilibration) was determined in a GLP-conform OECD 203 test of bismuth subnitrate (Bi5O(OH)9(NO3)4) and zebrafish D. rerio

- a 48-h EC50 (mobility) of >100 mg/L bismuth (WAF) was derived in a GLP-conform OECD 202 limit-test of bismuth subnitrate (Bi5O(OH)9(NO3)4) and Daphnia magna

- 72-h EC50 and NOEC (growth and biomass) values of > 100 and ≥ 100 mg bismuth/L (WAF, 7d equilibration) was determined in a GLP-conform OECD 201 test of bismuth subnitrate (Bi5O(OH)9(NO3)4) and P. subcapitata

- a 3-h EC10 and NOEC (respiration inhibition) of 175.4 mg/L and ≥ 300 mg/L bismuth (WAF, 7 d equilibration), respectively, were determined in a GLP-conform OECD 209 test with bismuth subnitrate (Bi5O(OH)9(NO3)4).  

In sum, bismuth has very low potential for acute aquatic toxicity due (at least in parts) to its low solubility and tendency to form insoluble salts in environmental solutions.  

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 > 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.

Bismuth (3+) neodecanoate

According to aquatic toxicity data of the dissociation products of bismuth (3 +) 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 bismuth and of neodecanoate ions are above respective OECD test limits.

Regarding chronic (long-term) toxicity, bismuth appears to have a very low potential based on the NOEC value of ≥ 100mg bismuth/L for algae. Existing freshwater toxicity data of neodecanoic acid and neoheptanoic acid are recalculated for bismuth (3+) neodecanoate based on a maximum neodecanoate content of 77.5 % in bismuth (3+) neodecanoate:

- 14-d NOEC of 2.87 mg/L for growth of Oncorrhynchus mykiss; Chronic Value (ChV) of 2.07 mg/L (QSAR-based estimate) for fish

- 21-Day NOEC of 6.17 mg/L for reproduction of D. magna; Chronic Value (ChV) of 2.19 mg/L (QSAR-based estimate) for daphnids

Regarding the toxicity to aquatic microorganisms, a hazard could not be identified for neodecanoate but for bismuth. The effect concentrations of bismuth were recalculated for bismuth (3+) neodecanoate based on a maximum bismuth content of 31.5 % in bismuth (3+) neodecanoate resulting in 3-h EC10 and NOEC(respiration inhibition) values of 604.8 and ≥ 952.4 mg/L on), respectively.