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. 2022 Sep 22;3:100166. doi: 10.1016/j.crmicr.2022.100166

Table 1.

Sources of HMs in the environment.

HM Sources Adverse effects of the HMs Significance of Heavy metal References
Cu2+ Fertilizers, Agricultural fungicides, electroplating, algicides Wilson's disease, headaches, nausea, dizziness due to long-term exposure An essential nutrient, Helps in the formation of RBC with Iron. Helps in bone formation, blood vessels, and the functioning of the immune system. (Khalid et al., 2021)
Cd2+ Agricultural fungicides, electroplating, algicides, Cd & Ni batteries, welding The cumulative toxin, carcinogenic, neural problems, and kidney failure. In plants, leads to tissue death No significant function in the human body.
Transported in the blood bound to metallothionein.
(Genchi et al., 2020)
Cr6+ Chrome plating, paints, dyes, ceramics Lung cancer, pulmonary illness Helps in the breakdown of carbohydrates and fats. Stimulate the synthesis of cholesterol and fatty acids. Helps in the action of insulin and also in the breakdown of glucose. (Tabelin et al., 2018)
Ni2+ Chrome plating, Cd & Ni batteries Allergic contact dermatitis. oxidative stress, nutritional imbalance in plants A micronutrient important for the proper functioning of the human body increases hormonal activity and helps in lipid metabolism.
A micronutrient in plants too and helps in nitrogen fixation and urea metabolism.
(Kuhn et al., 2022)
Zn2+ Refineries, metal plating, plumbing, brass manufacture Headaches, nausea, dizziness due to long-term exposure, Night blindness Zinc is important for the immune system to function properly and plays an important role in cell growth, cell division, also in wound healing. Helps in the breakdown of carbohydrates which is an important dietary nutrient. In zinc-deficient plants, chlorophyll synthesis is reduced significantly. (Kuhn et al., 2022)
As3+ Mining, smelting, fossil fuels, dietary intake (cereals, poultry, fish, and dairy products) Carcinogen leading to lung cancer and skin cancer, hyperpigmentation, keratosis In industries as an alloying agent for the smelting, used in textiles and paper industries, pesticides, feed additives but no significant function in the human body Sodhi et al., 2019