Bioaccessibility of lead and arsenic in traditional Indian medicines

Abstract

Arsenic and lead have been found in a number of traditional Ayurvedic medicines, and the practice of Rasa Shastra (combining herbs with metals, minerals and gems), or plant ingredients that contain these elements, may be possible sources. To obtain an estimate of arsenic and lead solubility in the human gastrointestinal tract, bioaccessibility of the two elements was measured in 42 medicines, using a physiologically-based extraction test. The test consisted of a gastric phase at pH 1.8 containing organic acids, pepsin and salt, followed by an intestinal phase, at pH 7 and containing bile and pancreatin. Arsenic speciation was measured in a subset of samples that had sufficiently high arsenic concentrations for the X-ray absorption near edge structure analysis used. Bioaccessible lead was found in 76% of samples, with a large range of bioaccessibility results, but only 29% of samples had bioaccessible arsenic. Lead bioaccessibility was high (close to 100%) in a medicine (Mahayograj Guggulu) that had been compounded with bhasmas (calcined minerals), including naga (lead) bhasma. For the samples in which arsenic speciation was measured, bioaccessible arsenic was correlated with the sum of As(V)–O and As(III)–O and negatively correlated with As–S. These results suggest that the bioaccessible species in the samples had been oxidized from assumed As–S raw medicinal ingredients (realgar, As4S4, added to naga (lead) bhasma and As(III)–S species in plants). Consumption at recommended doses of all medicines with bioaccessibile lead or arsenic would lead to the exceedance of at least one standard for acceptable daily intake of toxic elements.

Estimation of bioaccessibility and potential human health risk of mercury in Chinese patent medicines

“…The SBF test conditions were set up to be as close to the in vivo situation as possible to simulate the gastric and intestinal digestion process. The solid:liquid ratio was set to 1:100 and the two-stage extraction process was similar to that used by others (Cabanero et al, 2004;Koch et al, 2011) with slight modification (Fig. 1).…”

Bioaccessibility of mercury in selected Ayurvedic medicines

“…The deliberate addition of minerals, metals and metalloids to an herbal remedy is known as rasa shastra, and previous studies have shown that remedies prepared in this way can contain highly elevated concentrations of toxic metals like lead and mercury, as well as the toxic metalloid, arsenic (Saper et al, 2004(Saper et al, , 2008. Elevated concentrations can also be present in remedies not classified as rasa shastra, presumably from metals and metalloids introduced in plant material or incidentally during manufacturing (Saper et al, 2008;Koch et al, 2011).…”

“…Risk has been estimated for the use of several remedies according to dosing regimes indicated by the manufacturers of the medicines for mercury, lead and arsenic (Saper et al, 2004(Saper et al, , 2008Koch et al, 2011). For arsenic and lead risk calculations, the incorporation of solubility information, specifically bioaccessibility, decreased the number of medicines that exceeded acceptable daily intakes (Koch et al, 2011).…”

In Vitro Estimation of Lead Content in Nepalese Traditional Ayurvedic Medicines Commonly Used in Children

“…In a similar kind of study done by Koch I et al, bioaccessible lead was found in in 72% of the 42 samples of traditional Indian medicines 7 .…”