Preliminary investigation of metal and metalloid contamination of homeopathic products marketed in Croatia

BackgroundDue to their popularity as a complementary therapy in many diseases, homeopathic products of animal, vegetable, mineral and chemical origin should be tested for the presence of contaminants to prevent eventual toxic effects.ObjectiveThirty samples of homeopathic products were analyzed to estimate possible contamination with potentially toxic elements: Pb, Cd, As, Hg, Cr, Ni and Zn, and to assess human exposure to these metals/metalloid as a consequence of their consumption.MethodsAtomic absorption spectrometry was used to determine metal and metalloid concentrations.ResultsMost tested products had very low metal/metalloid levels (below the limit of quantification of the method), but the metal/metalloid levels in the remaining products were in the following ranges (in μg g−1): Pb 0.33–1.29 (6 samples), Cd 2.78 (1 sample), As 0.22 (1 sample), Hg 0.02–0.12 (24 samples), Cr 0.40–10.27 (10 samples), Ni 0.43–55.00 (19 samples), and Zn 2.20–27.80 (11 samples). In the absence of regulatory standards for homeopathic products, the obtained results were compared to maximum allowable levels (MALs) as proposed by USP Ad Hoc Advisory Panel. Some analyzed preparations had metal levels above MALs (Pb: 2 samples; Cd: 1 sample; Ni: 2 samples). However, estimated cumulative daily intakes from tested homeopathic products were in all cases lower than permitted daily exposures for all dosage forms.ConclusionThe risk of bioaccumulation of metals/metalloid from the homeopathic medicines seems to be rather low, due to small quantities of those products prescribed to be applied per day, as well as insignificant metal contamination of the majority of tested products. However, the fact that particular formulations were contaminated by metals above MALs indicates potential risk and points to the necessity of regular monitoring of homeopathic products for metal contamination, due to their frequent and mostly unsupervised use.