Bismuth tris(2-ethylhexanoate)

Endpoint summary

Description of key information

In the assessment of bismuth tris(2-ethylhexanoate), read-across to the assessment entities bismuth substances and 2-ethylhexanoic acid is applied since the ions of bismuth tris(2-ethylhexanoate) 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≥ 100mg 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. 

 

2-ethylhexanoic acid:

Acute data are available from studies for three trophic levels: algae, invertebrates and fish

- a 72-h ErC50 of 49.3 mg/L was identified for the algae Desmodesmus subspicatus (acc. To DIN 38412 part 9)

- a 48-h EC50 of 85.4 mg/L represents the lowest value identified for the invertebrate species Daphnia magna

- an unbounded value of > 100 mg/L (96-h LC50) was identified for the freshwater fish species Oryzias latipes based on data of an analogous substance (sodium 2-ethylhexanoate). Further studies of 2-ethylhexanoate with the freshwater fish species Oncorhynchus mykiss, Lepomis gibbosus and Leuciscus idus resulted in 96-h LC50 values > 100 mg/L

In sum, 2-ethylhexanoic acid has a low potential for acute aquatic toxicity.

Chronic data are available from studies for algae, aquatic invertebrates and microorganisms:

- a 72-h EC10 of 32.0 mg/L was identified for the green algae Desmodesmus subspicatus.

- 21-d NOEC values of 18 mg/L and of 25.0 mg/L were identified for Daphnia magna.

- 17-h EC10 and EC50 values of 71.7 and 112.1 mg/L, respectively, were derived for the inhibition of bacterial growth (Pseudomonas putida).

In sum, 2-ethylhexanoic acid has a very low potential for chronic aquatic toxicity to algae and invertebrates and appears to be of low toxicity to microorganisms.

 

bismuth tris(2-ethylhexanoate)

Using existing aquatic toxicity data of the dissociation products of bismuth tris(2-ethylhexanoate), the aquatic hazard assessment is based on the most toxic moiety, the 2-ethylhexanoate anion. Existing toxicity data of 2-ethylhexanoate are recalculated for bismuth tris(2-ethylhexanoate) based on a maximum 2-ethylhexanoate content of 69 %.

Acute data are available from studies for three trophic levels: algae, invertebrates and fish

- a 72-h ErC50 of 71.4 mg/L was identified for the algae Desmodesmus subspicatus

- a 48-h EC50 of 123.8 mg/L represents the lowest value identified for the invertebrate species Daphnia magna

- an unbounded value of > 144.9 mg/L (96-h LC50) was identified for the freshwater fish species Oryzias latipes based on data of an analogous substance (sodium 2-ethylhexanoate). Further studies of 2-ethylhexanoate with the freshwater fish species Oncorhynchus mykiss, Lepomis gibbosus and Leuciscus idus resulted in 96-h LC50 values > 144.9 mg/L.

 

Chronic data are available from studies for algae, aquatic invertebrates and microorganisms:

- a 72-h EC10 of 46.4 mg/L was identified for the green algae Desmodesmus subspicatus.

- 21-d NOEC values of 26.1 mg/L and of 36.2 mg/L were identified for Daphnia magna.

- a 17-h EC10 of 103.9 mg/L was identified for the inhibition of bacterial growth (Pseudomonas putida)

 

Regarding the toxicity to aquatic microorganisms, a hazard was identified for bismuth and 2 -ethylhexanoate with the latter resulting in a lower estimate. Thus, the effect concentrations of 2-ethylhexanoate were recalculated for bismuth tris(2-ethylhexanoate) based on a maximum 2-ethylhexanoate content of 69 % in bismuth tris(2-ethylhexanoate) resulting in EC10 and EC50 values of 103.9 and 162.5 mg/L, respectively.

Thus, bismuth tris(2-ethylhexanoate) has a low to moderate potential for toxicity to microorganisms.