Accumulation of Heavy Metals in Selected Medicinal Plants - Reviews of Environmental Contamination and Toxicology - page 66

Several regulations have already been established globally for medicinal plants
and related marketed herbal products; among the regulating entities are the fol-
lowing: the US Pharmacopoeia (USP), Italian Pharmacopoeia (FUI), and European
Pharmacopoeia (Ph. Eur.). Moreover, there are legal frameworks at national or
regional levels that are designed to regulate the quality of herbal products.
However, the existing medicinal plant regulatory guidelines are quite compli-
cated (Kosalec et al. 2009 ), which at times render them more dificult to follow.
There are also differences in standards and regulations among countries, which
may increase confusion, and cause a situation in which health risks to consumers
increases.
The literature that addresses quantiication of heavy metals in medicinal plants is
extensive and, as we have observed in preparing this review, when assembled, con-
tributes to a clearer understanding of the pattern for how metals accumulate in such
plants. In this context, our goals in this review are to evaluate the limits set by gov-
ernmental agencies for heavy metal safety in selected medicinal plants and to com-
pare these with the actual levels found in these plants. We also address some of the
uses and effectiveness to which medicinal plants are put in health care, and mention
some hazards associated with the use of medicinal plants.

2 Medicinal Plants in Health Care: Use and Effectiveness

Humans use many wild plant species for nutrition, for enhancing food security, for
medicines, and for sustainable development and livelihood management. In addi-
tion, the world's forests provide humans with several life-supporting commodities;
it is estimated that 350 million people worldwide live within or adjacent to dense
forests and depend on them for subsistence (Arnold 2001 ). In sub-Saharan Africa
(SSA) and Asia, the majority of people living in rural communities survive on less
than US $1 a day (World Bank 2001, 2004 ; FAO 2005 ; CIFOR 2002 ), and these
people largely sustain their livelihoods from forests. Most medicinal plants used in
traditional health-care systems contribute signiicantly to the caloric intake and
dietary nutrition of people who consume them, and such intake enhances human
health and cures various ailments. Aboriginal and tribal peoples are remnants of
primitive societies, and many such peoples continue to live close to nature, where
they have acquired unique knowledge concerning the sustainable use of wild medic-
inal plants. This knowledge has interestingly often spread to modern society, along
with the belief that such natural drugs are better and safer than synthetic ones.
Despite being based culturally on different theoretical models, medicinal plants
were used in all traditional medicinal systems, viz., Ayurveda, Chinese, Unani,
Tibetan, Amazonian, and African, which integrated phytotherapy into their doc-
trines (WHO 2007 ). Herbal medicines were and are often preferred in health care
over more modern chemicals, despite the fact that they may contain contaminating
chemicals obtained directly from contact with polluted air, water, and soil (Shamsa
et al. 2009 ). Medicinal plants are, nonetheless, used globally in many aspects of