Total and bioavailable polycyclic aromatic hydrocarbons in unused and operated heat-not-burn tobacco products and conventional cigarettes.

Tobacco product waste poses a global environmental issue, affecting urban and coastal areas alike. The present studies report, for the first time, the total and bioavailable polycyclic aromatic hydrocarbons (PAHs) concentrations in unused and operated heat-not-burn (HnBs) tobacco products. To enable direct comparisons, identical sets of studies were conducted using conventional cigarettes (CCs). Five low-molecular PAHs were determined in HnBs at total concentrations that were of the same order before and after operation (ΣPAH = 47.37 ± 3.44 ng unit and ΣPAH = 69.36 ± 5.78 ng unit in unused and used HnBs, respectively). The incomplete combustion of organics during smoking of CCs, yielded substantially higher amounts of PAHs with their sum (ΣPAHs = 1449 ± 113 ng unit) being >20 times larger than those in HnBs. The tobacco and filter were the most contaminated parts in HnBs. In unused CCs, tobacco had the highest PAHs load and after smoking, the spent filter was the most contaminated part, containing ∼80% of the total amount of PAHs. Naphthalene was the most abundant PAH detected in all tobacco products. Despite the high total PAH concentrations found in smoked CCs, the sums of the bioavailable PAH concentrations were of the same order in all tested tobacco products (ΣPAH = 61.38 ± 1.79 ng unit in unused HnBs, ΣPAH = 70.87 ± 7.67 ng unit in used HnBs, ΣPAH = 66.92 ± 5.95 ng unit in unused CCs, and ΣPAH = 47.94 ± 1.26 ng unit in smoked CCs). This finding was related to smoking affecting PAHs' leachability from CCs and delaying their desorption from the solid matrix. Adjusting the pH, salt and humic acids content at environmentally relevant values did not affect PAHs leaching at 24 h of soaking. Finally, the leaching behavior of PAHs in natural waters (river water, rainwater, and seawater) was found similar to that in ultrapure water, experimentally verifying the ability of tobacco product waste to leach PAHs into the aquatic environment.