Current findings on the heavy metal content in herbal drugs.

In this contribution, an overview on the current legal requirements regarding limits for heavy metals in plant material is given, drawing particular attention to the limits for lead, cadmium and mercury in herbal drugs proposed for the European Pharmacopoeia (Ph. Eur.). A new set of data resulting from about 7100 samples of herbal drugs (fresh and dried) tested for lead and cadmium and about 2500 samples tested for mercury between 2002 and 2007 is presented. Based on this evaluation the proposed limits for the Ph. Eur. can in principle be regarded as acceptable provided that exemptions are included for several herbal drugs, e.g. those accumulating cadmium. Such exemptions might be included either in the general monograph Herbal drugs or in individual Ph. Eur. monographs. For these herbal drugs, respective limits are proposed based on recent experiences from daily practice.