Naphthenic acids, lithium salts

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

no hazard identified

Marine water

Hazard assessment conclusion:

no hazard identified

STP

Hazard assessment conclusion:

no hazard identified

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:

no potential for bioaccumulation

Additional information

Lithium naphthenate consists of lithium salts of naphthenic acids. Therefore, data have been presented for both the organic anion and the lithium cation. Studies are included for naphthenic acids as well as lithium salts of docosanoic acid (C22) and dilithium adipate (C6). Naphthenic acids consist of a main acidic (naphthenic) fraction (70-95%), typically C8-C20 with 0-3 rings, and a smaller non-acidic (petroleum) fraction (5-30%), mainly of C12-C22 and no single constituent >10%. Lithium docosanoate (C22) has a longer chain length than the longest chain length acids present in the acidic fraction of lithium naphthenate (C20). Dilithium adipate (C6) is presented as a worst-case structural analogue as it has a shorter chain length than the shortest chain length acids present in the acidic fraction of lithium naphthenate (C8).

Short-term toxicity data are available for fish, invertebrates, algae and microorganisms. Long-term toxicity data are available for algae. The lowest short-term toxicity result is 5.62 mg/L for fish. The lowest long-term toxicity result is 3.2 mg/L for algae.

Conclusion on classification

Lithium naphthenate consists of lithium salts of naphthenic acids. Therefore, data have been presented for both the organic anion and the lithium cation. Studies are included for naphthenic acids as well as lithium salts of docosanoic acid (C22) and dilithium adipate (C6). Naphthenic acids consist of a main acidic (naphthenic) fraction (70-95%), typically C8-C20 with 0-3 rings, and a smaller non-acidic (petroleum) fraction (5-30%), mainly of C12-C22 and no single constituent >10%. Lithium docosanoate (C22) has a longer chain length than the longest chain length acids present in the acidic fraction of lithium naphthenate (C20). Dilithium adipate (C6) is presented as a worst-case structural analogue as it has a shorter chain length than the shortest chain length acids present in the acidic fraction of lithium naphthenate (C8). Data for these two substances bracket the chain lengths of the constituents within lithium naphthenate.

Short-term toxicity data are available for fish, invertebrates, algae and microorganisms. Long-term toxicity data are available for algae. The lowest short-term toxicity result is 5.62 mg/L for fish. The lowest long-term toxicity result is 3.2 mg/L for algae. As the lowest short-term toxicity result is 1-10 mg/L, lithium naphthenate does not meet the criteria for classification for acute aquatic toxicity. As the lowest long-term toxicity result is 1-10 mg/L, lithium naphthenate would not meet the criteria for classification for chronic aquatic toxicity. As long-term toxicity data are only available for algae and microorganisms, the short-term toxicity data are also considered for determining the chronic classification. However, the application of short-term toxicity values for chronic toxicity classification only applies where substances are not rapidly degradable and/or the determined BCF is greater than 500.

Lithium naphthenate is not considered to bioaccumulate in the aquatic environment and subsequently is not expected to pose a risk of secondary poisoning. The available data indicate that the lithium component of lithium naphthenate is expected to have a low potential for bioaccumulation, with a BCF of around 8 L/kg and QSAR estimates for the representative structures of lithium naphthenate have BCF values in the range of 3.162 to 207.7 L/kg. As lithium naphthenate is expected to have a BCF of well below 500 L/kg, the substance is considered to have low potential for bioaccumulation for classification purposes.

Furthermore, experimental data are provided which show that naphthenic acids can be degraded by adapted organisms and experimental data are provided which show that structural analogues for constituents in lithium naphthenate are readily biodegradable. QSAR estimates show that most representative structures are readily biodegradable. For the three representative structures that BIOWIN predicts to be not readily biodegradable (lithium salts of C11, 2 rings; lithium salts of C15, 3 rings; and lithium salts of C20, 3 rings), the level III STP fugacity model in EPISuite (US EPA 2010) states that these structures have an ultimate degradation half-life in water of 360 hours (equivalent to 15 days). Therefore, these structures are estimated to meet the criteria for rapidly degradable (demonstrated to be ultimately degraded in a surface water simulation test with a half-life of < 16 days).

Therefore, as lithium naphthenate is considered to be rapidly degradable and the BCF is less than 500, the substance is not considered to meet the criteria for chronic aquatic toxicity. This conclusion is supported by the lack of environmental classification for the naphthenic acids raw material (EC 215-662-8), as well as the structural analogues, dilithium adipate (EC 242-449-7) and lithium docosanoate (EC 224-801-1).