**3.3 Bioaccumulated toxicants**

The abuse of the natural ecosystem by a massive use of materials and energy to meet the demands of the world's growing population has led to a continuous and significant contamination of water, soil, and air. Industrial and agricultural activities are hugely responsible for the release of millions of tons of chemicals known as persistent, bioaccumulative, and toxic (PBT) into the environment. The interactional forces driving the relationship between the three environmental compartments (water, soil, and air) determine the fate of these pollutants, which undoubtedly have become part of nature. Medicinal plants grown in contaminated areas are usually susceptible to concentrating PBT chemicals. Dioxin, dioxin-like polychlorinated biphenyls (PCBs), some indicator PCBs [42, 43], metals [44–46], and phthalates [47–49], among others, are common environmental pollutants that can accumulate in plants in substantial and health-threatening quantities. Exposure to dioxins and dioxin-like substances has been associated with an avalanche of toxic effects during developmental stages, immunotoxicity, and adverse changes in thyroid and steroid hormones and also in reproductive functions [43]. Toxic metals found in botanicals may pose low health risk in one dose of herbal preparations [50] but can have a significant contribution to total body heavy metal burden [51, 52]. Major threats to human health from heavy metals are commonly associated with exposure to lead, cadmium, mercury, and arsenic [53] and have been linked to indicators such as decreased immunity, cardiac dysfunction, fetal malformation, and impaired psychosocial and neurological behavior [52]. Phthalates, globally used as plasticizers readily accumulate in medicinal plants [47, 48], have been found to be potent endocrine disruptors. In addition to endocrine-disrupting abilities, phthalates also possessed teratogenicity, carcinogenicity, and mutagenicity effects [54, 55]. Other toxicants with bioaccumulative capacities in medicinal plants abound. Some of these agents can bind covalently to enzymes and induce the production of reactive oxygen species (ROS), thus leading to negative health effects in humans [56].
