Heavy metals in nicotine-containing products: Sources, exposure, and health risks.

Traditional cigarettes remain a major global health threat due to their high content of toxic substances and well-established links to cardiovascular, respiratory, and oncological diseases. In recent years, a variety of novel nicotine products have emerged and are often promoted as potentially less harmful alternatives to conventional smoking. However, growing evidence indicates that these products are not risk-free. Their increasing popularity, particularly among adolescents, raises additional public health concerns driven by attractive flavors and marketing strategies. Chemical analyses demonstrate that both traditional and emerging nicotine products may contain toxic substances, including heavy metals such as mercury, cadmium, lead, arsenic, nickel, and chromium. Despite its well-documented toxicity, mercury remains one of the least investigated metals in nicotine products and is rarely included in toxicological assessments. In this interpretative review, we synthesize and critically analyze current evidence on heavy metal contamination in cigarettes, electronic nicotine delivery systems, snus, and tobacco-free nicotine pouches. Although alternative nicotine products may reduce exposure to combustion-related toxicants, users may still be exposed to harmful levels of heavy metals. These findings highlight the need for comprehensive monitoring, standardized analytical protocols, and strengthened regulatory strategies.