{'fraction_non_alphanumeric': 0.021095484826054774, 'fraction_numerical': 0.003700962250185048, 'mean_word_length': 5.286046511627907, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
E-Cigarettes and Toxin Exposure

IN RESPONSE: Dr. Aubin and colleagues argue that we have produced misleading claims about estimated risk reduction from switching from conventional cigarettes to e-cigarettes because duration of exposure is more important than degree of exposure in increasing risk for cancer. We acknowledge that assessing whether e-cigarette use actually reduces harm among conventional cigarette smokers is challenging and that the adverse health effects of tobacco are related to duration of use, not just exposure. However, both are essential causal factors and, to the extent that risk is broadly proportional to either, reducing the degree or duration of exposure will proportionally reduce risk. This correlation is supported by the evidence. Epidemiologic studies directly support a link between the degree of exposure to nitrosamines, and other tobacco-specific toxicants assessed in our study, and subsequent risk for cancer in smokers of conventional cigarettes (1) as well as lifelong never-smokers (2). On the basis of this evidence, significantly reduced exposure in e-cigarette users compared with users of conventional cigarettes likely reduces risk for cancer. Dr. Aubin and colleagues further contend that nicotine can have adverse effects. Although acknowledging that nicotine is not risk-freeparticularly for vulnerable populations, including pregnant women and adolescentsis important, postmarketing surveillance of licensed nicotine products and the epidemiologic evidence from adult users of snus (a form of smokeless tobacco that is low in carcinogens but high in nicotine) in Sweden indicate that such effects are small relative to other constituents of tobacco smoke (3). In the context of harm reduction, quantifying and comparing risks are crucially important. E-cigarette use can be expected to carry some risk, so adult smokers of conventional cigarettes who switch completely to e-cigarettes instead of quitting smoking without the aid of such a device will be worse off than they would have been. However, smokers who switch to e-cigarettes who would otherwise have continued smoking conventional cigarettes will benefit from a reduction in risk. Thus, a key determinant of whether e-cigarette use produces a public health gain is whether it causes more persons to stop smoking than would otherwise have been the case while not leading never-usersparticularly youthto initiate use of either product (4). The only population-level estimate undertaken thus far has been in England, and it used time-series analysis to estimate that an additional 20 000 former smokers per year were linked temporally with the increase in prevalence of e-cigarette use (5).