Lithium Citrate Tetrahydrate

Endpoint summary

Description of key information

Short-term toxicity to aquatic invertebrates:

Read-across with lithium hydroxide:

Lithium hydroxide (55.2 %) was tested for short-term aquatic toxicity in Daphnia in a 48-hour static test according to EU Method C.2 and OECD Guideline 202. Without pH-adjustment the 48 hour EC50-value was 19.1 mg/L. With pH-adjustment the 48-hour EC50-value was 34.3 mg/L for lithium hydroxide anhydrous. Based on these data, the calculated EC50 without pH-adjustment for lithium citrate tetrahydrate is 75 mg/L and with pH-adjustment 134.6 mg/L.

Read-across with citric acid:

Several effect data with Daphnia magna are indicted in the OECD SIDS Initial Assessment Report. The indicated EC50 values for Daphnia magna after 24 hours of exposure with citric acid range from 85 to 1535 mg/L. This corresponds to an EC50 range of 124.8 to 2252.9 mg/L for lithium citrate tetrahydrate.

Additionally, an LC50 for the saltwater crab Carcinus maenas of 160 mg/L is reported, which corresponds to an LC50 value of 234.8 mg/L for lithium citrate tetrahydrate.

Toxicity to aquatic algae and cyanobacteria:

Read-across with lithium hydroxide monohydrate:

Lithium hydroxide monohydrate was tested for toxicity to algae in a 72 h static test according to EU Guideline C.3 and OECD Guideline 201. The results showed an EC50 value of 153.44 mg/L based on growth rate (equivalent to 87.57 mg/L referred to lithium hydroxide anhydrous). The NOEC based on growth rate and biomass for lithium hydroxide monohydrate was 10 mg/L. Based on these data, the calculated EC50 and NOEC values for lithium citrate tetrahydrate are 602.19 mg/L and 39.25 mg/L, respectively.

Read-across with citric acid:

An EC0 of 640 mg/L in the green algae, Scenedesmus quadricauda, is reported in the OECD SIDS Initial Assessment Report after an exposure period of 7 days. This value corresponds to an EC0 of 939.34 mg/L for lithium citrate tetrahydrate.
For the saltwater species Chaetoceros gracilis, Navicula ramosissima (saltwater diatoms) and Pavlova lutheri (saltwater chrysophytes) the toxic limit concentration (TLC) is only given as a wide range between 1 and 300 mg/L. The recalculated TLC range for lithium citrate tetrahydrate is 1.47 to 440.3 mg/L

Additional information

Short-term toxicity to aquatic invertebrates:

A short-term toxicity study on aquatic invertebrates with lithium citrate tetrahydrate is not available. Consequently, read-across was applied using lithium hydroxide and citric acid.

 

Read-across with lithium hydroxide (FMC, Albemarle, 657652, 1997):

The acute toxicity of the test substance lithium hydroxide (55.2 %, i.e. test material was lithium hydroxide monohydrate but for the results the purity was considered, thus they refer to lithium hydroxide anhydrous) to Daphnia magna was determined in a 48-hour static test according to the EU method Annex Part C.2 and the OECD Guideline No. 202. The nominal concentrations tested were 4.6, 10, 21, 46 and 100 mg test substance/L, and in parallel a control. At one series of test media the pH was adjusted to approximately pH 8 by HCl, at the other series not. This allowed to differentiate if a toxic effect is caused due to a pH-effect of the test substance with a strong basic pH, or if it is a real toxic effect of lithium(-hydroxide). The analytical determined test substance concentrations in the analysed test media varied in the range from 93.5 % to 103.2 % of the nominal values. In the test media the test substance concentrations were constant during the test period of 48 hours. Therefore, all reported biological results are related to the nominal concentrations of the test substance.

Without pH-adjustment the 48 hour EC50-value was 19.1 mg/L and with pH-adjustment the 48-hour EC50-value 34.3 mg/L for lithium hydroxide anhydrous. Based on these data, the calculated EC50 without pH-adjustment for lithium citrate tetrahydrate is 75 mg/L and with pH-adjustment 134.6 mg/L. The value with pH-adjustment is the relevant value in this context (LiOH impact not relevant).

 

Read-across with citric acid (OECD SIDS 2001)

Additionally, aquatic toxicity data for citric acid are reported in the OECD SIDS Initial Assessment Report for citric acid (2001). An LC50 for the saltwater crab Carcinus maenas of 160 mg/L is reported, which corresponds to an LC50 value of 234.8 mg/L for lithium citrate tetrahydrate.

Further, several effect data with daphnia magna are indicated in the OECD SIDS Initial Assessment Report. The indicated EC50 values for daphnia magna after 24 hours of exposure with citric acid range from 85 to 1535 mg/L. This corresponds to an EC50 range of 124.8 to 2252.9 mg/L for lithium citrate tetrahydrate.

The low toxicity of citric acid to daphnia is further confirmed in a long-term toxicity test with daphnia magna in "soft-water", which is assumed not to buffer the acidic effect of the test substance. The EC0 was found to be 80 mg/L and the EC100 was 120 mg/L, resulting in a geometric mean EC50 of 98 mg/L.

Based on the results citric acid appears to be of low toxicity to daphnia magna and Carcinus maenas.

 

Conclusion:

Short-term toxicity data with aquatic invertebrates are available for the read-across substances lithium hydroxide and citric acid. The magnitude of the calculated LC/EC50 values show that lithium is the relevant toxicological moiety of lithium citrate tetrahydrate with respect to acute toxicity in aquatic invertebrates. The result of the daphnia magna acute immobilization study with lithium hydroxide is considered as valid and the EC50 of 134.6 mg/L for lithium citrate tetrahydrate is chosen as key value.

 

 

Toxicity to aquatic algae and cyanobacteria:

A study for aquatic algae and cyanobacteria with lithium citrate tetrahydrate is not available. Consequently, read-across was applied using lithium hydroxide and citric acid.

 

Read-across with lithium hydroxide monohydrate (FMC, Albemarle,559.820.2267, 2010):

The influence of the test item lithium hydroxide monohydrate on the growth of Pseudokirchneriella subcapitata was investigated in a 72 h static test according to EU method C.3 and OECD Guideline No. 201 in 2010.

The test item had a statistically significant inhibitory effect on the growth based on the average specific growth rate, yield and areas under the curves of Pseudokirchneriella subcapitata after the exposure period of 72 hours in the concentration range of 20 - 160 mg test item/L (Bonferroni t-Test, alpha=0.05). The test concentration of 20 mg/L was determined as the 72-hour LOEC. The results showed an EC50 value of 41.62 mg/L based on biomass and 153.44 mg/L based on growth rate. The NOEC based on growth rate for lithium hydroxide monohydrate was 10 mg/L.

Based on these data, the calculated EC50 and NOEC values (based on growth rate) for lithium citrate tetrahydrate are 602.19 mg/L and 39.25 mg/L, respectively.

Read-across with citric acid (OECD SIDS 2001) 

Additionally, data on the toxicity of citric acid to algae is reported in the OECD SIDS Initial Assessment Report for citric acid (2001). An EC0 of 640 mg/L in the green algae, Scenedesmus quadricauda, is reported in the OECD SIDS Initial Assessment Report after an exposure period of 7 days. This value corresponds to an EC0 of 939.34 mg/L for lithium citrate tetrahydrate.

For the saltwater species Chaetoceros gracilis, Navicula ramosissima (saltwater diatoms) and Pavlova lutheri (saltwater chrysophytes) the toxic limit concentration (TLC) is only given as a wide range between 1 and 300 mg/L. The recalculated TLC range for lithium citrate tetrahydrate is 1.47 to 440.3 mg/L

The saltwater species seem to be more sensitive the citric acid as the freshwater algae, Scenedesmus quadricauda. Still, citric acid appears to be of low toxicity to algae, in particular to freshwater algae.

Conclusion:
Toxicity data with aquatic algae are available for the read-across substances lithium hydroxide and citric acid. The guideline study with lithium hydroxide is considered as the more reliable study and is therefore chosen as key value.