Lithium carbonate

Toxicity to terrestrial plants

Administrative data

Endpoint:

toxicity to terrestrial plants: long-term

Data waiving:

other justification

Justification for data waiving:

other:

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
In accordance with column 2 of REACH Regulation (EC) No 1907/2006, Annex IX and X, in case no long and short term tests regarding toxicity to plants (required in section 9.4.3 and 9.4.6) are available , the equilibrium partitioning method may be applied to assess the hazard to soil organisms. According to its physico-chemical properties lithium carbonate is not expected to be distributed into soil and the ad-/desorption behaviour does not indicate that lithium will be present in the soil. The log Kd value for soil was found to be 2.57, i.e. adsorption potential to soil can be regarded as neglible (refer to IUCLID section 5.4). Thus, concentration and consequently effects in sediment are negligible. Additionally, carbonate naturally occurs in water and is a natural component of soil minerals. Therefore, no further testing is needed for the soil compartment.
An existing study with terrestrial plants (maize; Zea mays L., family: Poaceae) further shows that lithium exposure does not lead to any significant terrestrial toxicity to plants. In this study an LC50 of 140 mg/L was determined for treatment period of 2 months (rf. to IUCLID section 6.6 additional ecotoxicological information). This study can be regarded as worst case as the plants were treated under hydroponic conditions.

Cross-reference

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

additional ecotoxicological information

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

- Principle of test: Bioretention of lithium and its toxicity to maize was determined under hydroponic conditions.
- Short description of test conditions: Seeds of maize were used. Ten lithium concentrations in nutrient solution (each in four replicates) were tested: one control and 9 levels of lithium.
- Parameters analysed / observed:
1. Yield
2. Tolerance index
3. EC50
4. Lithium concentration in the individual plant parts
5. Translocation factor
6. Bioaccumulation factor
7. Lithium uptake was calculated
8. Utilization factor

GLP compliance:

not specified

Observations during the plants vegetation

Plants of the two highest concentrations were smaller and had shorter and thinner stems compared to the control. Chloroses, necroses and browning which usually resulted in leaf drying was observed regarding the above ground parts. The roots showed changes in colouring and growth inhibition. Plants exposed to lower concentrations were well developed.

Maize yield

Assuming the yield is an indicator of plant response to the presence of lithium in the nutrient solution, it needs to be stated that the concentration in solution ranging from 1 to 64 mg Li/dm³ had a stimulating effect, whereas a depression in yielding occurred only at the concentrations of 128 and 256 mg Li/dm³.

EC50 values

For assessment of lithium toxicity the concentration that results in a 50% reduction in the yield of maize (EC50) was determined as 140 mg Li/L for an exposure period of two months under hydroponic conditions.

Bioaccumulation factor

The following BAF values were determined for the different dose groups:

Doses	BAF
D1	—
D2	11.42
D3	12.87
D4	13.22
D5	14.42
D6	12.21
D7	13.23
D8	14.93
D9	15.69
D10	9.96

Executive summary:

Abstract:

"Irrigation of cultivated plants can be a source of toxic lithium to plants. The data on the effect of lithium uptake on plants are scant, that is why a research was undertaken with the aim to determine maize ability to bioaccumulate lithium. The research was carried out under hydroponic conditions. The experimental design comprised 10 concentrations in solution differing with lithium concentrations in the aqueous solution (ranging from 0.0 to 256.0 mg Li/L of the nutrient solution). The parameters based on which lithium bioretention by maize was determined were: the yield, lithium concentration in various plant parts, uptake and utilization of this element, tolerance index (TI) and translocation factor (TF), metal concentrations in the above-ground parts index (CI) and bioaccumulation factor (BAF). Depression in yielding of maize occurred only at the highest concentrations of lithium. Lithium concentration was the highest in the roots, lower in the stems and leaves, and the lowest in the inflorescences. The values of tolerance index and EC50 indicated that roots were the most resistant organs to lithium toxicity. The values of translocation factor were indicative of intensive export of lithium from the roots mostly to the stems. The higher uptake of lithium by the above-ground parts than by the roots, which primarily results from the higher yield of these parts of the plants, supports the idea of using maize for lithium phytoremediation."