Dilithium azelate

Endpoint summary

Additional information

Acute toxicity 

 

Testing was conducted for the dilithium salts of dicarboxylic acids (C6-C10) category for algae, fish and invertebrates in OECD 202, 203 and 201 tests respectively with all three substances (Tobor-Kaplon 2015). None of the substances in the category are considered to be acutely toxic to fish or invertebrates as all of the substances have EC50s> 100 mg/L. There were some inhibitory effects of the substances on algae but for dilithium sebacate and dilithium azelate the ErC50’s based on growth rate were ≥ 100 mg/L. The most sensitive result is for dilithium adipate with an ErC50 was 23 mg/L.

  

Chronic toxicity 

 

There is also data for chronic toxicity of the substances on algal growth inhibition. The NOEC’s based on growth rate were ≥ 100 mg/L for dilithium azelate, 10 mg/L for dilithium sebacate and 3.2 mg/L for dilithium adipate.

 

REACH Chapter R5 (ECHA 2011) states that chronic aquatic ecotoxicity testing may be triggered if the CSA indicates that there is a need to investigate further the effects on the environment. Testing may be triggered if additional testing could alter the conclusions on classification, PBT assessment or the level of concern. The dilithium salts of dicarboxylic acids (C6-C10) are readily biodegradable, have low potential for bioaccumulation and show low acute toxicity >10 mg/L. Furthermore, algae were the most sensitive species in the acute testing and chronic effects were also reported in the tests. Chronic toxicity based on NOECs for growth rate in OECD 201 tests for all three substances were >1 mg/L. Additional chronic toxicity tests would not be expected to change the classification or the conclusion that these substances are neither PBT nor vPvB. As the members of this category are not classified or considered to be PBT/vPvB, an exposure assessment is not required and no additional chronic testing is required to refine this assessment (ECHA R7b 2012).  

     

However, as long-term aquatic toxicity is required under Annex IX, a testing proposal has been submitted for long-term toxicity to fish and invertebrates testing on dilithium sebacate to complete the endpoints required under the registered tonnage band. 

 

In addition to the long-term toxicity data on category members, assessments of metal salts should consider the inorganic moiety if the substances dissociate rapidly or both the inorganic moiety and the substances themselves if the dissociation rate is unknown. As there is currently no experimental data on the rate of dissociation of the substances in the lithium salts of dicarboxylic acids C6-C10 category, data are presented here on the lithium ion for completeness.

 

In aqueous environments, the substances in the lithium salts of dicarboxylic acids C6-C10 category would dissociate into carboxylic acids and lithium ions. The acids used for the formation of the salts in this category are readily biodegradable and data on the aquatic toxicity of the acids is available in the respective registration dossiers. Data on the lithium component of the salts are available in the dossiers for soluble lithium salts such as lithium carbonate and lithium hydroxide.

 

In a long-term toxicity test withDanio rerio, a LOEC of 24.35 mg/L and a NOEC of 17.35 mg/L were determined based on lithium hydroxide monohydrate, which are equivalent, respectively, to 4.03 and 2.87 mg/L for lithium and 45.8 and 32.7 mg/L for dilithium adipate. In a long-term toxicity test withDaphnia magna, a LOEC of 2.53 mg Li/L and a NOEC of 1.70 mg Li/L were determined, which are equivalent to 28.8 and 19.4 mg/L for dilithium adipate. In a toxicity test with lithium hydroxide on algae, an EC50 of 87.57 mg/L and a NOEC of 5.71 mg/L for lithium hydroxide anhydrous (equivalent to 153.44 mg/L and 10.0 mg/L for lithium hydroxide monohydrate) were determined, which are equivalent to 288.9 and 18.8 mg/L for dilithium adipate. In a toxicity test with lithium carbonate on algae, an EC50 of 400 mg/L, an EC10 of 90 mg/L and a NOEC of 50 mg/L for lithium carbonate were determined, which are equivalent to an EC50 of 855.3 mg/L, an EC10 of 192.5 mg/L and a NOEC of 106.9 mg/L for dilithium adipate. The lowest result of a NOEC of 18.8 mg/L for dilithium adipate has been read across to all substances in the lithium salts of dicarboxylic acids C6 – C10 category, following a worst-case approach as dilithium adipate is the shortest chain length substance in the category and contains the highest proportion of lithium, calculated as 8.79% lithium.

 

Based on analysis of the lithium and acid components respectively, the water solubilities of dilithium adipate was 343 g/L and 406 g/L, for dilithium azelate was 192 g/L but the results based on azelate analysis were not conclusive and for dilithium sebacate were 76.6 g/L and 68.5 g/L. The calculated results for long-term aquatic toxicity based on lithium would be below the solubility limit of the substances.

 

The lowest result of a NOEC of 18.8 mg/L calculated for dilithium adipate based on lithium toxicity to algae is higher than the experimental value of 3.2 mg/L for dilithium adipate so the experimental value for the substance will be used in the conclusion on aquatic toxicity and read across to the other category members.

 

Sediment toxicity 

 

No data are available for the toxicity to sediment organisms. Sediment toxicity data is not a data requirement at the registered tonnage band. 

 

The sediment toxicity of the substances in the lithium salts of dicarboxylic acids C6-C10 category is not considered to be scientifically relevant. Lithium salts of dicarboxylic acids C6-C10 are readily biodegradable, have low potential for bioaccumulation, and show no acute or chronic aquatic toxicity at the limit of solubility. The substances have log Kow values of <0 so they have very low potential for adsorption/desorption to sediment.