Full Length ArticleAn in vitro cytotoxic approach to assess the toxicity of heavy metals and their binary mixtures on hippocampal HT-22 cell line

- This study examined the cytotoxicity and apoptosis of Pb, Cd, As, and MeHg and their mixtures interaction on HT-22 cell line.
- The single metal results showed potency dependent response with potency order on HT- 22 cells as: MeHg > As > Cd > Pb.
- Both effect additivity and dose additivity were used for the mixture toxicity analysis.
- Toxicity order of current mixtures on HT-22 cells, Pb + MeHg > MeHg + As > Cd + As found in both dose and response addition.
- The interactive responses of mixtures were dependent on the nature of co-exposure metal and concentration.

Humans are exposed to a cocktail of heavy metal toxicants in the environment. Though heavy metals are deleterious, there is a paucity of information on the toxicity of mixtures. In this study, four common neurotoxicity heavy metals lead (Pb) cadmium (Cd), arsenic (As), and methylmercury (MeHg) were exposed individually and as mixtures to HT-22 cell line for 8 days. The study established that low dose exposures induced toxicity to the HT-22 cell line during 8 days. The results indicates potency dependent response, the toxicity of single metals on the HT-22 cells; MeHg > As > Cd > Pb. The cytotoxicity data of single metals were used to determine the mixtures interaction profile by using the dose additivity and effect additivity method. Metal mixtures showed higher toxicities compared to individual metals. Synergistic, antagonistic or additive effects of the toxicity were observed in different mixtures in low dose exposure. The interactive responses of mixtures depend on the co-exposure metal and their respective concentration. We concluded that the combined effects should be considered in the risk assessment of heavy metal co-exposure and potency. In future, comprehensive mechanistic based investigations needed for understanding the real interactive mixtures effects at molecular level.