Occurrence and Importance of Heavy Metals

The term “heavy metals” refers to natural metallic elements with a density greater than 5g/cm3. Some heavy metals are an important part of our diet as trace elements, others are toxic in even low concentrations. Heavy metals occurring in water, air and earth include elements such as mercury, lead, cadmium, copper, arsenic, nickel, zinc, cobalt and manganese. The focus lies especially on the severely toxic heavy metals lead, cadmium and mercury and regular tests for these elements are required in both the pharmaceuticals and food sectors.

The path of heavy metals

Heavy metals find their way into the environment from natural resources (minerals, ores), which do not initially pose any danger to human health, as a result of mining, erosion or volcanic activity, as well as through industry (ore smelting, paint manufacturing, cement works, fertilisers, sewage sludge, pesticides). Heavy metals are also used in numerous industrial processes.

Heavy metals in medicinal plants and herbs

Plants absorb heavy metals from the earth, the water or the air. The absorption of heavy metals by plants depends on a wide range of factors. The heavy metal content in medicinal plants and herbs can therefore vary considerably. Some medicinal plants such as birch leaf or St. John’s wort are well-known for absorbing cadmium. In others, such as stinging nettle root or Iceland moss, you can expect a higher lead content.

You can find an overview of the heavy metal content in pharmaceuticals and herbal medicines in the publication “Zur Schwermetallbelastung von Arznei- und Kräuterdrogen” by Dr. Lothar Kabelitz [1] and the publication “Current Findings on the Heavy Metal Content in Herbal Drugs” co-authored by Dr. Bernhard Klier [2].

References:
[1] KABELITZ, L.; Zur Schwermetallbelastung von Arznei- und Kräuterdrogen, Pharmazeutische Industrie, 60, 5, 1998 pp. 444 – 451
[2] GASSER, U.; KLIER, B.; KÜHN, A.V.; STEINHOFF, B.; Current findings on the heavy metal content in herbal drugs, Pharmeuropa, 21, 1, 2009 pp. 37 – 49