Accumulation of Heavy Metals in Selected Medicinal Plants - Reviews of Environmental Contamination and Toxicology - page 63

Accumulation of Heavy Metals in Selected
Medicinal Plants

Hemen Sarma, Suresh Deka, Hemen Deka, and Rashmi Rekha Saikia

Contents
1 Introduction...................................................................................................................... 63

2 Medicinal Plants in Health Care: Use and Effectiveness................................................. 66

3 Heavy Metal Accumulation in Selected Medicinal Plants: Cause and Threat ................ 68

4 Safe Limits vs. Actual Levels of Heavy Metals in Medicinal Plants............................... 69

5 Hazardous Medicinal Plants ............................................................................................ 69

6 Conclusions...................................................................................................................... 81

7 Summary .......................................................................................................................... 81

References.............................................................................................................................. 82

1 Introduction

Heavy metals (HMs) are natural components of the Earth's crust and are usually
present in all environmental matrices. However, the concentration of several HMs
has increased several fold in some ecosystems as a result of anthropogenic activities.
Heavy environmental metal contamination has continued to gain global attention,
mainly because of the toxicological risks posed by such metals to human health
(Ayodeji and Olorunsola 2011 ). Although metallic elements are often essential for
living organisms, they become toxic when present at high concentrations (Elekes
et al. 2010 ). The rapid increase in human population, coupled with haphazard indus-
trialization and technological advancement, has caused many serious environmental
problems around the world; among the causes of such problems is the production and
release of toxic metals. In the past few decades, the concentration of heavy metals in