HEAVY METAL SAFETY OF RASAUSHADHI: A CRITICAL REVIEW OF PRECLINICAL TOXICITY AND CLINICAL SAFETY EVIDENCE
Background: Rasaushadhi, the herbo-mineral and herbo-metallic formulations of Ayurveda, intentionally contain metals such as mercury, lead, arsenic, copper and gold. Their safety is contested: case reports of poisoning sit alongside a long classical tradition and a growing body of animal studies reporting no toxicity at therapeutic doses. Objective: To review what the preclinical and clinical evidence shows about the heavy metal safety of Rasaushadhi, and to identify what is needed to settle the question. Methods: A critical narrative review of market surveys, case reports and case clusters, animal and zebrafish toxicity studies, and clinical safety studies, with attention to chemical speciation, dose and study design. Results: Market surveys consistently detect lead, mercury or arsenic in a substantial share of Ayurvedic products, more often in Rasa Shastra products, and some at levels far above herbal medicine limits. Case reports and clusters of lead poisoning are well documented. Animal and zebrafish studies of processed mercurials, bhasmas and compound formulations generally report low toxicity at therapeutic doses and differences from simple mercury salts, but most are short-term, use single products and rarely measure tissue metal accumulation. Clinical safety studies are few, small and seldom report blood or urine metal levels. Conclusion: The evidence does not support either blanket claims of safety or blanket bans. Safety depends on chemical form, dose, duration and product quality. Long-term studies with biomonitoring, product-level quality control and active pharmacovigilance are required.