Abstract:
Accelerating heavy metal pollution is a hot issue due to a continuous growth in consumerism
and increased activities in various global industries. Soil contamination with heavy metals
has resulted in their incorporation into the human food web via plant components. Accumulation
and amplification of heavy metals in human tissues through the consumption of medicinal plants
can have hazardous health outcomes. Therefore, in this critical review we aim to bring together
published information on this subject, with a special highlight on the knowledge gaps related to
heavy metal stress in medicinal plants, their responses, and human health related risks. In this
respect, this review outlines the key contamination sources of heavy metals in plants, as well as the
absorption, mobilization and translocation of metal ions in plant compartments, while considering
their respective mechanisms of detoxification. In addition, this literature review attempts to highlight
how stress and defensive strategies operate in plants, pointing out the main stressors, either biotic or
abiotic (e.g., heavy metals), and the role of reactive oxygen species (ROS) in stress answers. Finally,
in our research, we further aim to capture the risks caused by heavy metals in medicinal plants to
human health through the assessment of both a hazard quotient (HQ) and hazard index (HI).
