Plant-based foods contain plant-derived substances, such as cereals, legumes, kernel seed, vegetables and fruits. Plant-based foods are an important part of the human daily diet that can be contaminated with toxic metals such as Hg, Cd, Pb and As, therefore plant-based foods are considered a serious concern for human health (Stefanović et al. 2008) (Dodangeh et al. 2018). The contamination of plant-based food with toxic metals can be related to either natural resources or human activities such as industrial processing, mining, waste disposal and application of wastewater as well as sewage sludge to irrigation of cultivated plant-based food or even application of fertilizers (especially phosphate type) and pesticides(Tadesse et al. 2015; Marrugo-Negrete et al. 2015; Shariatifar et al. 2020; Shariatifar et al. 2017). It is worthy to note that the atmospheric deposition could be accounted as the primary sources of soil, and water contaminations and consequently further contaminations in the food chain (Fakhri et al. 2017). In this regard, plants can absorb toxic metals from the soil, water and air and furthermore concentrate them in different parts such as roots, leaves, and grains (Qu et al. 2012).
Toxic metals as the non-essential compounds for the human body could cause several adverse health effects, even in trace amounts (Yılmaz et al. 2010). Due to their non-degradable nature, they could biologically accumulate in different tissues (kidney, liver, bone, and brain) after their intake through diet as well as inhalation pathways (Bjørklund et al. 2017). For instance, the consumption of contaminated food with Cd can cause bone pain, cardiovascular diseases, and kidney damages (Cheng et al. 2017). Pb can accumulate in the bone and can cause gastrointestinal colitis, hypertension, kidney damages, leukemia, brain dysfunctions, and thrombotic illnesses in human (Fang et al. 2014).
Hg is one of the major pollutants that can cause to brain problems such as hearing, vision and tactile disorders(Raj and Maiti 2019). It has been noted that the developmental disorders in infants and children such as lowering intelligence quotient (IQ) can be correlated with Hg and Pb (Raj and Maiti 2019; Marrugo-Negrete et al. 2015).
In this context, the International Agency for Research on Cancer (IARC) categorized Pb as (group 2B) and Cd as (group 1) a human carcinogenic compound (Cancer 1993). As may cause cancer in human in various organs including the lung, skin, blood and skeleton. (Sarkar and Paul 2016).
The investigation of toxic metals (Cd and Pb) were carried out in the word (all over it) by different analytical methods (Vinas et al. 2000; Salah et al. 2013). Among several method to determine the trace metals in the food samples, the ICP-OES, flame atomic absorption spectrometry (FAAS), and graphite furnace atomic absorption spectrometry (GF-AAS) are the original techniques. Due to saving the time, specificity and more sensitivity of ICP-OES, these technique, it is regarded as better method (Karimi et al. 2012). In various study, agricultural soil is generally considered to be one of the main sources and receptors for heavy metals. However, in Markazi province, the presence of heavy metals in the soil may be from various sources such as industrial activities, lead and zinc mines and fuel combustion, greenhouse gas emissions and municipal waste disposal. Excessive entry of heavy metals and synthetic chemicals into the studied soils may lead to deterioration of the soil biology, thereby altering the physicochemical properties of the soil and causing other environmental problems. Increasing the pollution of air, water and soil caused by highway traffic, mines, various manufacturing industries and industrial waste is a serious problem that negatively affects the public health (Qu et al. 2012; Salama and Radwan 2005; Islam et al. 2020; Proshad et al. 2018; Solgi et al. 2014; Solgi et al. 2012; Ghasemidehkordi et al. 2018b; Ghiyasi et al. 2010; Hani and Karimineja 2010). However, no research has been done to investigate the concentration of toxic metals in foods of plant origin, obtained from the industrial areas of Markazi province as one of the most industrialized regions of Iran. Also, this is the first attempt to measurement and compare toxic metals content in plant-based food in the industrial areas of Markazi province using an inductively coupled plasma-optical emission spectrometry (ICP-OES). Therefore, the present research is devoted to evaluate the toxic metals concentration in selected plant-based food (legumes, potatoes, and wheat) in Markazi Province. Furthermore, the Chronic Daily Intake (CDI) of toxic metals besides the non-carcinogenic risk in children and adult population were estimated.