Toxicological analysis of Pb and Cd by ET AAS in local anaesthetics for teething (teething gels) based on herbs available in Polish pharmacies

Studies related to the toxicological analyses of metallic impurities in pharmaceuticals (drugs) is an important issue but there is a lack of refereed literature around the safety of teething remedies from herbal origin related to toxic metals impurities. In this article, the levels of Pb and Cd were measured in samples of local anaesthetics for teething (gels) based on herbs. This article was motivated by the fact that Pb and Cd are relevant toxic metals that may cause an adverse effect in babies even at low levels. Additional justifications were (1) the insufficient control of metal impurities in teething gels, (2) the lack of sufficient validation steps and (3) the inadequate sensitivity of applied analytical techniques. The aim of this article was a qualitative and quantitative analysis of Pb and Cd in the most popular and available local anaesthetic for teething (teething gels) based on herbs (n = 5) available in Poland. Metals were determined by ET AAS (electrothermal atomization atomic absorption spectrometry), after digestion in a microwave unit using concentrated nitric acid. It was observed that all samples contained Pb and Cd. The levels of Pb and Cd as impurities (independently of the producer and declared composition) are similar. The concentrations of Pb and Cd, at ng/day levels, to which the user is exposed at daily doses meet the standards of the directive ICH Q3D.