Bioaccessibility of lead and arsenic in traditional Indian medicines
Authors
Iris Koch
aEnvironmental Sciences Group, Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Canada
Maeve Moriarty
aEnvironmental Sciences Group, Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Canada
Kim House
aEnvironmental Sciences Group, Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Canada
Jie Sui
aEnvironmental Sciences Group, Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Canada
William Cullen
bChemistry Department, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, Canada V6T 1Z1
Robert Saper
cDepartment of Family Medicine, Boston University School of Medicine, One Boston Medical Center Place, Dowling 5 South, Boston, MA 02118, USA
Kenneth Reimer
aEnvironmental Sciences Group, Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Canada
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.
Keywords: Arsenic, Lead, Bioaccessibility, Ayurvedic, Speciation, Risk
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