Silica (28,08 a.m.u.). One of the most circulated natural elements. Contains 26% of Earth crust. Human body contains small amounts of it and concentration decreases with ageing. Silica deficit could develop if too small amounts are intaken (less than 5mg/day), but the toxicity level is 500 mg/day. The highest concentration of silica is in aortic wall, trachea, joints, bones, skin and hair.  Role of silica in conjunctive tissue structure is very important.

Silica deficit causes inhibition of growth, fragility of nails and hair, flail joints rotation (simultaneous deficit of calcium and silica). Its deficit damages bone structure, causes abnormal changes of cartilaginous tissue and joints, causes development of atherosclerosis, hypertonia, and atherosclerotic heart disease, deposition of aluminium in brain. Excreted from the body with urine and excrements; in cases of increased intake (e.g. professional treatment of silica dust), excretion of silica with urine is being slightly increased.

Silica and its compounds are being widely used in production of foodstuffs, pharmacology and medicine. Especially dangerous toxic effect of silica oxides and various silicates, asbestos in particular. Inhalation of dust containing such agents causes deposition in lungs and degradation of lungs tissues, pneumoconiosis (silicosis).

Methylated silica polymers (silicon) are used in implants. Women with silicone implants has silica concentration in their blood higher than others, but stays within the normal limit of variations of this indication among healthy people. Silica level in blood correlates to the presence of implant, not to the existence of joints diseases. Increased concentration of silica could indicate diseases of water-salt metabolism and danger of kidney stone disease, degenerative disc disease, arthrosis and atherosclerosis.