Estimation of Cadmium Levels in Local Banana (Musa) Fruits by ICP-MS Technology-A Pan India Study

Heavy metals are naturally occurring elements in the earth crust. Industrial activities, smelting (Kumar et al., 2019) causes air, water and soil pollution with heavy metals and is a serious threat to the environment and human life (Singh et al., 2011). Despite occupational exposure, cadmium contained foods, smoking are also major sources Cd toxicity (Song et al., 2017). Cd destroys lungs, liver, kidney, and skeletal muscle (Nisha et al., 2009). Cadmium element is present in the soil and water habitat can easily uptake by flora. Plants accumulate cadmium in the edible parts (Zhang et al., 2014). Irrigation water, soil of India are having cadmium levels greater than WHO alert value (Idrees et al., 2018; Taghipour et al., 2012). 
       
Phosphate fertilizers are also a source for Cd accumulation in the agriculture industry (Lugon-Moulin et al., 2006). Regular consumption of metal toxicated plant parts on long exposure increases the toxic metal in the human body. This cause bio-magnification of cadmium. Cadmium also decreases plant growth and metabolism (Bindhu and Bera, 2001). Banana is a common table fruit eaten as dessert item in India. Banana plants growing in cadmium polluted soil, water accumulate Cd in the edible parts. To measure the banana cadmium levels and its prevalence, we performed an experiment of quantifying the banana cadmium levels by ICP-MS technique and how the cadmium is prevalent in different districts of India.

Banana fruit consumed as staple food in many countries of the world. Present study was designed to study the amount of cadmium levels in banana fruit samples. Measured cadmium levels were expressed in nano grams/ gram of banana fruit edible potion. The detected cadmium levels fell in between the range of 0.014 ng/g to 0.86 ng/g. Table  2.1.
 

       
Among the 59 districts studied in India, 28 districts were having banana with levels of 0 - 0.19 ng/g, 13 districts were having 0.2 - 0.3 ng/g, 12 districts were having 0.31 - 0.4 ng/g, four districts are having 0.41 - 0.5 ng/g. The districts of Tiruchirapalli and Bahraich had banana cadmium levels respectively, 0.51 - 0.6 ng/g, 0.81 - 0.9 ng/g. Details are mentioned in the Table 2.2 
 

       
A total of 10 Indian districts were having lower banana cadmium levels. They were having the cadmium range of 0.01 - 0.12 ng/g. Names of the districts with lower banana Cd levels were Namakkal (Tamil Nadu), Nagarkovil (Tamil Nadu), Vellore (Tamil Nadu), Pathankot (Punjab), Sivakasi (Tamil Nadu). Estimated Cd levels were shown in the Table 3.
 

       
Some of Indian districts were also having high Cd levels. We have listed 5 districts containing higher banana cadmium levels. These five districts were having banana cadmium levels in between 0.34 - 0.86 ng/g. The name of the districts were Bahraich (Uttar Pradesh), Tiruchirapalli (Tamil Nadu), Tirupur (Tamil Nadu), Belgaum (Karnataka) and Bengaluru (Karnataka). Estimated Cd levels were shown in the Table 4.
 

 
Banana plant species (Musa spp.) are widely distributed and cultivated varities of the world. India is the largest producer for banana fruits (Padam et al., 2014). Economically, banana fruit are affordable to have. Heavy metal toxicity is a challenge to the ecosystem. In soil in which banana is cultivated, the levels of cadmium reached to 0.43 - 3.21 mg/kg dry weight (Dian et al. 2010). Significant levels of cadmium were found in fruits and vegetables. Banana fruits cultivated in Libya country had cadmium levels of 0.01 - 0.362 mg/kg (Elbagermi et al., 2012).
 
High availability of cadmium in the soil, either by natural or anthropogenic activities could be the cause of cadmium metal accumulation in the plant body. Plant organic acids, ion exchange process influence cadmium update through root system. Plants take up cadmium by non-selective cation channels of plasma membrane. Root hairs radially distribute absorbed nutrients in the cortex through endodermis and permeates into stele parenchymal tissue for eventual assemble into the xylem water current (Yu et al., 2017). Low affinity cation transporters increase cadmium transport from xylem to phloem (Uraguchi et al., 2011) that reaches to storage organs viz. fruit, fleshy stem or tubers etc. Cadmium accumulated banana fruits bio-accumulates cadmium in the food chain.
 
Indian subcontinent, is having different ecosystems with significant heavy metals pollution in its abiotic components. Our analysis demonstrated that banana crops are exposing to heavy metals stress and accumulated the metals in their edible parts. Bahraich district of Uttar Pradesh was having highest highest level of cadmium.

Sweet fleshy fruits are good diet supplements. In India, majority of population consume banana fruit. Consumption of metal toxicated banana fruits accumulates heavy metals in body. Bio-magnification of Cd through banana could cause fatality to consumers. Our study has also provided a valid conclusions of Indian banana fruits containing significant levels of cadmium. This will educate Indian citizens, government bodies for the imminent hazards of cadmium heavy metal.

Our sincere thanks to the Management, Thyrocare Technologies Limited, for providing the facilities and a opportunity to complete the study on time. Special thanks go to Miss Kajal Rai for active participation in the work. All authors have contributed substantially to the writing of manuscript. 

This work is not funded by any Government or non-governmental funding agencies. Therefore all authors of this manuscript agreed to declare that, there is no potential competing financial interests.