Investigation of some metal levels in people using electronic cigarettes and IQOS

There has been a sharp increase in the use of e-cigarettes and heated tobacco products (HTPs) in the last decade. Related to the increase in the use, serious public health debates have been caused by the safety and risks of these products. Particularly due to the exposure to a lot of toxic substances, including heavy metals, there has been an increasing concern over their health effects. Heavy metals such as lead, arsenic, mercury, and cadmium are environmental pollutants poising significant health risks. These metals have a disposition to accumulate in the human body over time. Even at lower levels of exposure, they might lead to multiple organ damage and adverse health effects, including neurotoxicity, nephrotoxicity, and being carcinogenicity.

This study tests the idea that using electronic cigarettes (e-cigarettes) and IQOS devices raises the levels of metals in urine and that the amount of increase depends on which product is used. The study aims to look at the levels of lead, cadmium, nickel, zinc, and selenium in the urine of cigarette smokers, e-cigarette users, IQOS users, and nonsmokers; to check for significant differences in metal levels between these groups (with a significance level set at p < 0.05); to compare the metal levels found with safety limits; and to explore if there's a link between the metal levels in urine and the type of product used (cigarettes, IQOS, or e-cigarettes).

This study aimed to compare the trace element, heavy element, and nicotine exposures of individuals who smoke (n = 39), use e-cigarettes (n = 28), use IQOS (n = 20), and do not use tobacco or tobacco products (n = 30) while living in Ankara, Türkiye. In order to evaluate the element levels of the participants, the levels of lead, cadmium, nickel, zinc, and selenium metals in their urine were determined using inductively coupled plasma mass spectrometry (ICP-MS), and nicotine exposures were determined using liquid chromatography-tandem mass spectrometry (LC-MS/MS).

The measurement showed that lead levels were higher in IQOS users (8.51 ng/g creatinine) and smokers (3.67 ng/g creatinine) compared to e-cigarette users (1.38 ng/g creatinine), and this difference was statistically significant (p < 0.05). In addition, a statistically significant difference was found between the cotinine level and lead level of the smoking and IQOS groups (p ˂ 0.05). No statistically significant difference was found between the groups in terms of cadmium level (p > 0.008). Nickel level was found to be higher in e-cigarette (3.43 ng/g creatinine) and IQOS (3.84 ng/g creatinine) users than in the smoking group (0.99 ng/g creatinine). In terms of nickel, a statistically significant difference was found between the e-cigarette and IQOS groups and both the smoking and control groups (p ˂ 0.05). No statistically significant difference was found between the selenium level and both the groups and the cotinine level (p > 0.008). Zinc levels were higher in IQOS users (596.13 ng/g creatinine) than in e-cigarette users (298.40 ng/g creatinine) and cigarette users (217.59 ng/g creatinine). No statistically significant difference was found between the cotinine levels of e-cigarette, IQOS, and cigarette users (p > 0.05).

This study investigated metal exposure profiles by comparing urinary metal concentrations across different groups of tobacco product users (cigarette smokers, IQOS users, and e-cigarette users). The findings revealed that lead and cadmium levels were significantly higher in cigarette smokers compared to nonsmokers. In contrast, elevated nickel concentrations were notably observed among IQOS and e-cigarette users. Variations in zinc and selenium levels appeared to be more attributable to physiological or external factors rather than product use. Overall, the results suggest that both conventional and novel tobacco products may pose potential toxicological risks related to metal exposure among users. However, the observed metal concentrations generally fell below established regulatory thresholds.