Dose-dependent toxicity profile and genotoxicity mechanism of lithium carbonate.

The increasing widespread use of lithium, which is preferred as an energy source in batteries produced for electric vehicles and in many electronic vehicles such as computers and mobile phones, has made it an important environmental pollutant. In this study, the toxicity profile of lithium carbonate (Li2CO3) was investigated with the Allium test, which is a bio-indicator test. Dose-related toxic effects were investigated using Li2CO3 at doses of 25 mg/L, 50 mg/L, and 100 mg/L. The toxicity profile was determined by examining physiological, cytotoxic, genotoxic, biochemical and anatomical effects. Physiological effects of Li2CO3 were determined by root length, injury rate, germination percentage and weight gain while cytotoxic effects were determined by mitotic index (MI) ratio and genotoxic effects were determined by micronucleus (MN) and chromosomal aberrations (CAs). The effect of Li2CO3 on antioxidant and oxidant dynamics was determined by examining glutathione (GSH), malondialdehyde (MDA), catalase (CAT) and superoxide dismutase (SOD) levels, and anatomical changes were investigated in the sections of root meristematic tissues. As a result, Li2CO3 exhibited a dose-dependent regression in germination-related parameters. This regression is directly related to the MI and 100 mg/L Li2CO3 reduced MI by 38% compared to the control group. MN and CAs were observed at high rates in the groups treated with Li2CO3. Fragments were found with the highest rate among CAs. Other damages were bridge, unequal distribution of chromatin, sticky chromosome, vagrant chromosome, irregular mitosis, reverse polarization and multipolar anaphase. The genotoxic effects were associated with Li2CO3-DNA interactions determined by molecular docking. The toxic effects of Li2CO3 are directly related to the deterioration of the antioxidant/oxidant balance in the cells. While MDA, an indicator of lipid peroxidation, increased by 59.1% in the group administered 100 mg/L Li2CO3, GSH, which has an important role in cell defense, decreased by 60.8%. Significant changes were also detected in the activities of SOD and CAT, two important enzymes in antioxidant defense, compared to the control. These toxic effects, which developed in the cells belonging to the lithium-treated groups, were also reflected in the tissue anatomy, and anatomical changes such as epidermis cell damage, cortex cell damage, flattened cell nucleus, thickening of the cortex cell wall and unclear vascular tissue were observed in the anatomical sections. The frequency of these changes also increased depending on the Li2CO3 dose. As a result, Li2CO3, which is one of the lithium compounds, and has become an important contaminant in the environment with increasing technological developments, caused a combined and versatile toxicity in Allium cepa L. meristematic cells, especially by causing deterioration in antioxidant/oxidant dynamics.