Heavy metal hazards of Nigerian smokeless tobacco

Interest is rising in smokeless tobacco as a safer alternative to smoking. Information on the heavy metal hazards of smokeless tobacco is sparse in Nigeria, as it is in most sub-Saharan Africa countries. This study assesses the heavy metal hazards of the smokeless tobacco types commonly available in Nigeria.

Using a market basket protocol 30 Nigerian smokeless tobacco types were studied. Digestion was performed by addition of 10 mL of a mix of nitric and hydrochloric acids (HCl:HNO3, 3:1); the mixture was then heated to dryness. Then, 20 mL deionised water was added, and the mixture stirred and filtered. The filtrate was made up in a standard volumetric flask and lead, cadmium, chromium, cobalt and nickel concentrations were assayed with atomic absorption spectrophotometry at 205 Å. The daily intake and target hazard quotient (THQ) were calculated.

Chromium, cobalt and nickel concentrations ranged from 2.77-11.40, 0.01-0.03 and 0.02-0.07 μg/g, respectively, whereas lead and cadmium ranged from 0.00-2.48 and 0.01-0.17 μg/g, respectively. The daily intake of chromium, cobalt and nickel ranged from 277-1140, 1-3 and 2 to 7 μg/day, respectively. Lead and cadmium daily intakes ranged from 0-248 and 1-17 μg/day, respectively.

Although there was no apparent risk when each metal was analysed and considered individually, the potential risk could be multiplied when considering all heavy metals. The high heavy metal content in Nigerian smokeless tobacco may have public health implications.