Dilanthanum tricarbonate

Long-term toxicity to aquatic invertebrates

Description of key information

No effects on long-term toxicity to aquatic invertebrates is to be expected up to the limit of water solubility

Additional information

Only one study for long-term toxicity to aquatic invertebrates is available for Lanthanum carbonate, but this study is not valide because the mean surviving offspring per parent animal did not reach the pass level of >= 60. Therefore, further data from the analogue approach source substance Cerium carbonate were taken into account as well as further data from Lanthanum chloride.

The effect of Cerium carbonate on the survival and reproduction ofDaphnia magnawas investigated in a semi-static test over 21 days following OECD 211 (Höger 2009). Daphnids were exposed to control and test item at nominal concentration of 130 mg/L (loading rate) and the dilutions 1:3.2, 1:10, 1:32 and 1:100 of the saturated solution. The saturated solution was prepared by stirring the dispersion of 130 mg/L over six days. Then, the undissolved test item was allowed to deposit at the bottom of the stirring vessel until the supernatant appeared to be a clear solution (24 hours), thus the test medium was not filtered. The wide range of measured concentrations (0.011 – 30 mg/L) of the test item was considered to be caused by very fine particles of the test item which were obviously still present in the supernatant after the deposition period. Therefore, the test medium contained the maximum concentration of dissolved test item and very fine undissolved test item particles.

Cerium carbonate had no toxic effect on survival and reproduction ofDaphnia magnaafter the exposure period of 21 days up to the loading rate of 130 mg/L. Thus, the NOELR of the test item was determined to be at least the loading rate of 130 mg/L (100 mg/L dw,). The LOELR was above the loading rate of 100 mg/L dw.

The study with Lanthanum carbonate was also conducted withDaphnia magnaaccording to OECD 211 under GLP conditions (Muckle 2010). Two test concentrations were used with 1 and 5 mg/L test substance(nominal), the higher concentration lays above the water solubility of Lanthanum carbonate (1.24 mg/L at 20 °C) the lower concentration in the range of the water solubility. Analytical measurements in old and new (renewal) filtrated medium showed, that the detectable concentrations were very low; the mean measured concentrations were 0.010 and 0.021 mg/L test substance. Since the medium specified in OECD 211 included a chelating agent (EDTA) which could reduce the toxicity of metals, reconstituted hard water according to ASTM E729-96 was used. Even though this medium was recommended for metals, the validity criteria “mean surviving offspring per parent animal in control ≥ 60 was not reached and therefore, the study has to be disregared. Nevertheless, the study supports the assessment, that up to the limit of water solubility no effect of Lanthanum carbonate is to be expected on reproduction and mortality to daphnids: The reproduction rate of the two tested treatments ( 1 and 5 mg/L, filtered test solution) was greater compared to the control.

In general the measured water solubility of Lanthanum and Cerium carbonate (1.24 and 3.96 mg/L, respectively) correspond to the water solubility in deionised water. In culture media the solubility of the substances will considerably be reduced, since the media contain a remarkable amount of carbonate (e.g. hardness as CaCO3 is 150 mg/L in the ASTM E729-96 medium). This expected reduction of solubility is confirmed by the analytics of the above described tests, which showed a remarkable reduction of solubility. If released into the environment further reduction of the test concentrations with regard to the high adsorption potential is possible.

 

Whereas no long term toxicity effects could be observed for the poorly soluble rare earth compounds up to the limit of solubility, soluble substances containing Lanthanum, e.g. Lanthanum trichloride hydrate, showed long-term toxicity effects toDapnia magna(Bogers, 1995). In a GLP -study equivalent to OECD 211 the NOEC (21 d) was determined as 0.176 mg/L (LOEC (21d) = 0.406 mg/L), based on Lanthanum trichloride, anhydrous.

Due to the limited solubility of Lanthanum and Cerium carbonate in test medium, which reflects the situation under environmental conditions and as the case may be overestimate the natural occurring concentration, it is to be expected, that the effect concentrations of the soluble Lanthanum substance will not be achieved for the poorly water soluble Lanthanum carbonate.

Therefore, a long term toxicity effect of Lanthanum carbonate on aquatic invertebrates within its solubility is not to be expected.

Further information about the analogue source substances can be found in the data matrix of the justification for the analogue approach, which can be found either in the CSR or as attachment in IUCLID section 13.

Bogers M. (1995). Daphnia magna, reproduction test with Lanthanum (La). Testing laboratory: NOTOX B. V., s´Hertogenbosch, The Netherlands. Report no.: 139499. Owner company: Kemira Pernis B. V.,Rotterdam, The Netherlands. Report date: 1995-03-31.