Potential health risks of exposure to toxic metals in e-cigarettes
As the use of e cigarettes continues to grow worldwide, research on the potential health risks associated with these devices is also increasing. The National Academies of Sciences, Engineering, and Medicine recently concluded that while e cigarettes are not without health risks, they are likely to be far less harmful than conventional cigarettes. Because e cigarettes generate an aerosol by heating an e-liquid with a metallic coil, a possibility exists for transfer of metals from the coil to the aerosol. There is a growing concern that e cigarettes may be a potential source of exposure to metals. The objective of this study is to evaluate potential health risks associated with exposure to metals in e cigarette-generated aerosol in comparison with conventional cigarette mainstream smoke using quantitative risk assessment (QRA). Metal concentrations in machine-generated e cigarette aerosol and conventional cigarette mainstream smoke were obtained from the literature. Potential health risks were evaluated following a standard QRA process, utilizing toxicity values from regulatory sources and standard default exposure factors from the U.S. Environmental Protection Agency (USEPA) and U.S. Food and Drug Administration (FDA), supplemented with assumptions to estimate lifetime exposures. Cadmium accounts for over 80 % of the health risk attributable to metals in conventional cigarette smoke. However, cadmium was rarely detected in e cigarette aerosol, and other metals present in e cigarette aerosol were reported at much lower levels than in conventional cigarette smoke. Estimated cancer risks of metals in e cigarette aerosols did not exceed the USEPA’s acceptable level of 1 in 1,000,000 and non-cancer hazards are 100 to 10,000 times below the USEPA acceptable level. These risk estimates for metals in e cigarette aerosols represent greater than 99 % reduction compared with conventional cigarette smoke. Based on these findings, the potential health risk from exposure to metals from e cigarettes is orders of magnitude below estimated risk from conventional cigarettes.