Environmental Contaminants – Heavy Metals Origin – Analytical Methods – Points to Consider

Environmental relevant heavy metals are lead, cadmium, mercury, arsenic, copper, nickel, zinc and iron. Since Tschernobyl and actually Fukushima caesium 137 and even plutonium 239 might be relevant parameters for some proveniences.

The input of these elements into herbal materials is diverse. Some of them like nickel, arsenic or lead are from direct geogenic sources and therefore not avoidable at all. Other inputs are made via air by traffic, industry and combustors also. Even the agricultural industry itself takes part in that scenario by using heavy metal loaded pesticides like some dithiocarbamates (zinc in zineb and others) or anorganic mineral fertilizers (accumulation of cadmium in the soil).

Some plants are so called hyperaccumulators for heavy metals at all. Even some of the herbal drugs used for phytopharmacy are found in that group (e.g. Salix and Populus). In that group results for cadmium found often exceed the specified limits.

Methods and limits are described in the European Pharmacopoeia in the chapters 2.4.27, 2.4.31 and in the monograph „Herbal Drugs“ (monograph number 1433).

The official testing methods for heavy metals are atomic absorption spectrometry (AAS) or inductively coupled plasma-atomic emission spectrometry (ICP-AES) or inductively coupled plasma-mass spectrometry (ICP-MS). All methods need to be validated on the herbal materials at least on distinct plant organs like roots or fruits etc.

Points to consider in the management of GACP to avoid OOS results for heavy metals are control of the soil, specified pest management, specified selection of plants and varieties.

Keywords: Heavy Metals, absorption spectrometry (AAS), or inductively coupled plasma-atomic emission spectrometry (ICP-AES), inductively coupled plasma-mass spectrometry (ICP-MS)