Is mercury really toxic? The way forward for its judicious medicinal applications based on the therapeutic doctrines of Ayurveda

Abstract

Mercury-based formulations have been extensively used in Indian and Chinese systems of medicine with high therapeutic index. However, at present mercury is considered as a global pollutant having potent neurotoxic effects. Also, it has been proposed to ban the export, import and manufacture of a range of products containing mercury from 2021. This situation compels one to ponder how mercury-based formulations were safe during ancient times, but are now considered to be toxic. Naturally mercury occurs in three forms, viz. elemental (Hg), inorganic (HgS, HgCl2) and organic (MeHg). Organic mercury is completely absorbed by gastrointestinal tract, and elemental mercury is 75-80% absorbed by the lungs only in vapour state, while 10% of inorganic mercury is absorbed by the gastrointestinal tract. Additionally, organic mercury crosses the blood brain barrier and placenta, producing neurotoxic symptoms and foetal toxicity. In Ayurvedic science, mercury is converted only into inorganic form with special stabilization technology and this stabilized mercury is converted to mercuric polysulphides under gastrointestinal conditions, whereas elemental mercury is converted to organic form by specific bacteria. Thus mercury available in the atmosphere is converted into organic form that is highly toxic, while using Ayurvedic methods it is converted to inorganic form having potent therapeutic activity. Judicious and injudicious application of mercury has advantageous and disadvantageous effect respectively.