Abstract
The revised Promotion Act, enforced in April 2020, allows the establishment of dedicated smoking rooms for heated tobacco products (HTPs). Since carcinogenicity assessment is unable to determine the safe level of secondhand smoke, we estimated excess lifetime cancer risk using previously reported risk factors. Assuming that nicotine inhalation is proportional to cancer potency, the lifetime cancer risk for HTP IQOS is expected to be below 10(-5) (1/100,000), which is three orders of magnitude lower than that for cigarettes.