Inhalation Bioaccessibility of Potentially Toxic Metals in Tobacco Snuff and Related Exposure Risks

Abstract

This study determined the concentrations and inhalation bioaccessibility of cadmium, chromium, nickel and zinc in some foreign and locally available tobacco snuff and leaves. For the determination of the heavy metals concentration, the samples were ashed and washed with hydrochloric acid according to standard method. The bioaccessibility test employed the Stimulated Epithelial Lung Fluid (SELF). The total concentration of heavy metals in the four samples investigated ranged between 9.7 - 14.9 μg/g, 24.1 - 37.0 μg/g, 41 - 69 μg/g and 153 - 183 μg/g for cadmium, chromium, nickel and zinc respectively. The percentage inhalation bioaccessibility fraction of the four samples investigated ranged between 20.8% - 59.8%, 3.3% - 8.1%, 21.7% - 48.8% and 7.6% - 12.5% for cadmium, chromium, nickel, and zinc respectively. Statistical analyses using SPSS 21, revealed significant differences in the total concentration of heavy metals in the samples investigated except for Zinc. Risk assessment based on daily consumption of 10 g of the tobacco snuff employing total concentration of the heavy metals suggests that excluding nickel, all other metals investigated indicated daily intake values above WHO permissible levels. However, with the bioaccessible fractions, only cadmium, a known carcinogen indicated levels above WHO limits. From the results of this study, it can be deduced that consumption of tobacco snuff may induce negative health effects such as cancer and its attendant complications, the risk analysis based on bioaccessible concentration suggests lower health risk than analysis based on total heavy metal concentration; hence the assumption that snuff is a safe alternative to tobacco smoking may be erroneous.