Table 2.

Chemical elements in human body and their classification.

Class	Elements	Concentration
Essential elements	H, O, C, Ca, Mg, N, Na, K, Mg, P, S	Comprise 99.9% of human body
Major elements	C, H, N, O	> 1%, comprise 3–65% of human body
Minor elements	Ca, Cl, K, Mg, Na, P, S	0.1–1% (1000–10,000 ppm)
Trace elements	As, Br, Co, Cr, Cu, F, Fe, I, Li, Mn, Mo, Ni, Se, V, W, Zn	< 0.1%