Bismuth(3+) neodecanoate

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.617 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.062 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

55.56 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

no hazard identified

Sediment (marine water)

Hazard assessment conclusion:

no hazard identified

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

no hazard identified

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

PNEC oral

PNEC value:

0.022 g/kg food

Assessment factor:

90

Additional information

Read-across approach

 

Metal carboxylates are substances consisting of a metal cation and a carboxylic acid anion. Based on the solubility of bismuth (3+) neodecanoate in water, a complete dissociation resulting in bismuth cations and neodecanoate anions may be assumed under environmental conditions. The ions of bismuth (3+) neodecanoate are considered a hard acid and a hard base, respectively. Bismuth carboxylates were analysed for the presence of covalent and ionic bonds between bismuth and the oxygen of the carboxylate group. It was confirmed that bismuth carboxylate bonds are ionic (Mehrotra and Bohra 1983). The equilibrium equation of the dissociation products does not indicate any pH dependency of the dissociation. The dissociation of bismuth (3+) neodecanoate is in principle reversible and the ratio of the salt /dissociated ions is dependent on the metal-ligand complexation constant of the salt, the composition of the solution and its pH.

 

A metal-ligand complexation constant of bismuth (3+) neodecanoate could not be identified. Data for bismuth appear to be generally limited. However, bismuth cations tend to form complexes with ionic character as a result of their low electronegativity. Further, the ionic bonding of bismuth is typically described as resulting from electrostatic attractive forces between opposite charges, which increase with decreasing separation distance between ions. Bi3+ cations are acidic and have a strong tendency to form insoluble salts (hydroxides) in water reducing its bioavailability (reference given in HSDB, 2008; Thomas et al. 1984; Thomas, 1991). Further insoluble bismuth salts include oxides, sulphides and oxychlorides, salts of inorganic oxoacids (carbonate, nitrate, sulfate) and organic acids (triglycollate, trialkylates) (Fowler and Vouk, 1979). However, uncertainties regarding the behaviour of bismuth species in aqueous solutions remain (Slikkerveer and De Wolff, 1996 and references therein). Upon dissolution of bismuth (3+) neodecanoate, bismuth (3+) ions are expected to form insoluble salts that reduce its bioavailability whereas neodecanoate anions remain dissolved in the water column.

 

Thus, read-across to bismuth cations and neodecanoate anions is applied since the dissociation products of bismuth (3 +) neodecanoate behave differently in the environment regarding their fate and toxicity. A separate assessment of each assessment entity is performed. Please refer to the data as submitted for each individual assessment entity.

 

In order to evaluate the environmental fate and toxicity of bismuth (3+) neodecanoate, information on the assessment entities bismuth cations and neodecanoate anions were considered. For a documentation and justification of that approach, please refer to the separate document attached to section 13, namely Read Across Assessment Report for bismuth (3+) neodecanoate.

 

References:

Mehrotra, R. C. and Bohra R. (1983): Metal Carboxylates. Academic Press

HSDB (2008). Hazardous substances data bank (HSDB), a database of the national library of medicine’s TOXNET system.

Fowler, B. A. and Vouk, V. (1979). Chapter 20, Bismuth, in Handbook on the Toxicology of Metals, Friberg et al. (Edt), Elsevier, North-Holland Biomedical Press.

Slikkerveer, A. and De Wolff, F. (1996). Chapter 27, Toxicity of Bismuth and Its Compounds, CRC Press, Inc., p. 439-454.

Thomas, D.W., Hartley, T. F. and Coyle, P. (1984), II.5 Bismut, Met. Umwelt, Adelaide, p. 343-350. Krieger, R. (Ed.) (2001). Bismuth, Handbook of pesticide toxicology, p. 1389-1390.

Thomas, D. W. (1991). II.5 Bismuth, Met. Their Comp. Environ., p. 789-801.

Conclusion on classification

Aquatic toxicity studies with bismuth (3+) neodecanoate are not available. For the assessment of the aquatic hazard potential of bismuth (3+) neodecanoate, read-across of existing aquatic toxicity data of the dissociation products bismuth cations and neodecanoate anions is applied.

Acute (short-term) toxicity:

EC/LC50 values of 3 trophic levels (algae, invertebrates and fish) for bismuth and neodecanoate are > 100 mg/L, respectively and thus well above the classification cut-off value for acute (short-term) aquatic hazard category 1 of 1 mg/L. In accordance with Regulation (EC) No 1272/2008, Table 4.1.0 (a), classification for acute (short-term) aquatic hazard is not required for bismuth (3+) neodecanoate.

Chronic (long-term) toxicity:

Bismuth appears to have a very low potential for chronic toxicity based on the NOEC value of ≥ 100mg bismuth/L for algae. Based on its very low acute toxicity (all EC/LC50 values are > 100 mg/L) and its tendency to form insoluble and non-bioavailable salts in aquatic systems, a low potential for chronic toxicity to other trophic levels may be expected for bismuth. Based on the surrogate approach (Table 4.1.0 (b) (iii)) of Regulation (EC) No 1272/2008, bismuth would also not meet chronic classification criteria since the EC50 for crustacea and fish are > 100 mg/L. Criteria for the "Safety net" classification in Category Chronic 4 are also not met.

Regarding the aquatic toxicity of neodecanoate, reliable data and QSAR-based estimates are available for daphnids and fish. The respective NOEC/EC10 values are > 1 mg/L. 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.

Therefore,bismuth (3+) neodecanoate does not meet classification criteria as long-term hazard to the aquatic environment under Regulation (EC) No 1272/2008.

 

In sum, based on read-across of toxicity data available for bismuth and neodecanoate, bismuth (3+) neodecanoate does not meet acute or long-term aquatic hazard criteria of Regulation (EC) No 1272/2008.