Heavy Metal Contamination in Medicinal Plants: Sources, Plant Defense Mechanisms, and Implications for Human Health

Medicinal plants are employed extensively in traditional and contemporary healthcare systems, but heavy metal contamination seriously threatens their safety and effectiveness. The fact that both organic and inorganic materials from the air, soil, and water may be easily absorbed by plants and subsequently transferred up the trophic chain to humans makes this study important. The World Health Organization estimates that 65-80% of people worldwide rely on herbal items as their main source of medical care. This study explores the primary sources of heavy metal pollution, including industrial discharge, agricultural runoff, and atmospheric deposition, that contribute to the accumulation of toxic elements in therapeutic plant habitats. The synthesis of phytochelatins, the activation of antioxidant enzymes, and changes to root architecture are only a few of the physiological and biochemical defense mechanisms that plants employ in response to metal-induced stress. Despite these adaptations, prolonged or high-level exposure can impair plant growth and reduce the concentration of therapeutic phytochemicals. Moreover, the consumption of contaminated medicinal plants can cause bioaccumulation of heavy metals (HMs) in humans, posing risks like increased cancer susceptibility, neurological disorders, and organ damage. Addressing this issue requires stringent quality control, pollution mitigation strategies, and public awareness to safely use medicinal plant-based remedies.