“…These studies were grouped by their system of research. The most commonly studied system of research was blood cells (9) [40] , [41] , [42] , [43] , [44] , [45] , [46] , [47] , [48] followed by whole body (8) [49] , [50] , [51] , [52] , [53] , [54] , [55] , [56] , blood plasma (4) [39] , [57] , [58] , [59] , tissues (2) [60] , [61] , urine (2) [62] , [63] , saliva (1) [64] , and other cells (1) [65] .…”