Abstract

Rasa Sastra, the metallurgical–chemical branch of Ayurveda, presents one of the most sophisticated premodern frameworks for the therapeutic use of metals and minerals. Among these, Parada (mercury) occupies a unique position due to its exceptional physicochemical properties, potent medicinal efficacy, and inherent toxicity. Classical Sanskrit texts consistently emphasize that mercury in its unprocessed state functions as a potent poison (viṣa), whereas after undergoing systematic Sodhana Saṃskara (detoxification and purification), it becomes a therapeutically viable and rejuvenative agent. The present review critically examines Parada Sodhana through an interdisciplinary lens integrating classical Rasa Sastra literature, modern inorganic chemistry, toxicology, and analytical science. Drawing upon authoritative Sanskrit texts such as Rasarṇava, Rasaratna Samuccaya, Rasa Hṛdaya Tantra, and Ayurveda Prakasa, alongside contemporary experimental and toxicological studies, this paper establishes that Sodhana is not a ritualistic process but a scientifically coherent chemical detoxification strategy. The analysis demonstrates that Sodhana operates through multiple synergistic mechanisms, including controlled oxidation–reduction, sulfidation, chelation, phase transformation, and chemical stabilization, leading primarily to the formation of mercury sulfide (HgS), a thermodynamically stable and poorly bioavailable compound. Modern analytical evidence from X-ray diffraction (XRD), scanning electron microscopy (SEM–EDS), Fourier-transform infrared spectroscopy (FTIR), and in vivo toxicological studies corroborates classical claims by confirming the absence of elemental mercury, reduced bioavailability, minimal bioaccumulation, and significantly attenuated neuro-renal toxicity in properly processed mercury preparations. This review further highlights the epistemological sophistication of Rasa Sastra, revealing that ancient practitioners implicitly recognized principles of chemical speciation, stabilization, and toxicokinetics centuries before the formal development of modern toxicology. At the same time, the study acknowledges the need for standardization, quantitative validation, and regulatory oversight for contemporary application.