Heavy metals concentration and human health risk assessment in tobacco cigarette products from Tanzania

Cigarette smoke contains various harmful substances, including heavy metals, that pose significant health risks. Tobacco smoking is the leading cause of lung cancer, accounting for approximately 90 % of lung cancer-related deaths worldwide. However, limited information is available on the health hazards posed by heavy metals in cigarettes commonly consumed in Tanzania. This study aims to assess the potential health risks associated with heavy metal exposure from eight most commonly consumed cigarette products in Tanzania using atomic absorption spectrometry. The concentrations (mg kg⁻¹) of copper (Cu), zinc (Zn), cadmium (Cd), chromium (Cr), and nickel (Ni) ranged from 6.94 to 16.31, 0.6–1.93, 0.4–0.66, 0.69–2.86, and 0.11–2.69, respectively, with mean concentrations of 9.35, 0.92, 0.52, 1.82, and 1.24 mg kg⁻¹. The mean concentrations of Cu and Zn are within the permissible limits set by FAO/WHO while Cd, Cr, and Ni exceeded these limits, raising concerns. A high positive correlation is observed between Cu and Zn ($r=0.988$, $p=0.01$). The non-carcinogenic hazard quotient (HQ) for ingestion is below 1, indicating minimal risk, whereas HQ for inhalation is above 1, indicating considerable health risk. The carcinogenic risk assessment for ingestion is within acceptable limits for all metals. However, Cd, Cr, and Ni present higher risks than the acceptable limit set by USEPA (1E-06 to 1E-04), suggesting significant cancer risk associated with these metals. This study highlights the need for stringent regulation and monitoring of heavy metal content in cigarettes to mitigate health risks.