ENVIRONMENTAL TOXICOLOGY AND RISKS ASSOCIATED WITH HUMAN HEALTH Growth and physiological response of spinach to various lithium concentrations in soil Hafiz Faiq Bakhat 1 & Kunwar Rasul 1 & Abu Bakar Umar Farooq 1 & Zahida Zia 1 & Natasha 1 & Shah Fahad 2,3 & Sunaina Abbas 1 & Ghulam Mustafa Shah 1 & Faiz Rabbani 1 & Hafiz Mohkum Hammad 1 Received: 16 July 2019 /Accepted: 24 October 2019 # Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract Lithium (Li) exploitation for industrial and domestic use is resulting in a buildup of the element in various environmental compo- nents that results in potential toxicity to living systems. Therefore, a soil culture experiment was conducted to evaluate the effects of increasing concentration of Li (0, 20, 40, 60, and 80 mg kg -1 soil) on spinach growth, the effects of Li uptake, and its effects on various physiological attributes of the crop. The results showed that lower levels of Li in soil (20 mg Li kg -1 ) improve the growth of spinach plants, while a higher concentration of applied Li enhanced the pigment contents. Higher concentrations of Li in soil interfered with potassium and calcium uptake in plants. Moreover, increasing Li concentration resulted in higher activities of antioxidant enzymes activity in spinach shoots. From these results, it is concluded that spinach shoot accumulated higher concen- trations of Li without showing any visual toxicity symptoms. Therefore, the study concludes that Li ion was mostly deposited in leaves rather than in roots which may cause potential human health risk on the consumption of Li-contaminated plants. Therefore, the cultivation of leafy vegetables in Li-affected soils should be avoided to reduce the potential human health risks. Keywords Antioxidant enzymes . Lithium . Physiological attributes . Spinach . Toxicity Introduction Lithium (Li) is the lightest monovalent cation among the alkali metals. It ranks the 25th most abundant element with a concen- tration of 20 mg kg -1 in the soil (Kavanagh et al. 2018). Majority of Li is present in the soil as part of minerals like spodumene with minimum solubility in water and dilute acids. Weathering of rocks, minerals, and downstream movement of water increase its concentration in irrigated soils. In addition, Li-based rechargeable batteries; grease used to reduce friction; industries like ceramics, glass, and pharmaceuticals; certain weapons; and nuclear reactor coolants use this element (Kszos and Stewart 2003). Furthermore, Li 2 CO 3 is used as a mood stabilizer and as a drug to treat bipolar disorders. Therefore, natural and anthropogenic activities are resulting in higher Li concentrations in the environment (Jiang et al. 2018). Traces of Li are required for proper function of human and animals; however, higher concentration may result in chronic and acute toxic effects in animal and humans (Shahzad et al. 2016). Daily requirement of 1 mg day -1 70 kg -1 adults has been recommended for humans (Shahzad et al. 2017). Vegetables and drinking water almost contribute 66–90% of the Li dietary requirements (Magalhães et al. 1990; Schrauzer 2002). Similarly, low levels of Li also produced beneficial effect in crop plant species under stress as well as no stress conditions (Aral and Vecchio-Sadus 2008 ; Kalinowska et al. 2013). Lithium application to cucumber lowered the incidence of powdery mildew (Abood et al. 1991). Similarly, Li-supplied spinach mesophyll cells better adapted to low-temperature–induced changes and showed sta- bilized microtubules with lower de-polymerization level (Bartolo and Carter 1992 ). On the contrary, higher Responsible editor: Gangrong Shi * Hafiz Faiq Bakhat faiqsiddique@ciitvehari.edu.pk * Shah Fahad shah_fahad80@yahoo.com; shahfahad@uoswabi.edu.pk 1 Department of Environmental Sciences, COMSATS University Islamabad, Vehari-Campus, Islamabad 61100, Pakistan 2 Department of Agriculture, University of Swabi, Khyber Pakhtunkhwa, Pakistan 3 College of Plant Science and Technology, Huazhong Agriculture University, Wuhan, China Environmental Science and Pollution Research https://doi.org/10.1007/s11356-019-06877-2