School of Public Health & Health Systems, University of Waterloo, Waterloo, ON, Canada.
Nicotine Tob Res. 2018 Apr 2;20(5):649-653. doi: 10.1093/ntr/ntx103.
Tobacco-specific nitrosamines (TSNAs) are potent carcinogens. Levels of TSNAs can be modified through manufacturing practices. In the 2000s, TSNA levels in cigarettes sold in Canada were reduced by changes in tobacco curing processes. The current study examined TSNA levels over the following decade to examine trends over time.
Data submitted to Health Canada under the Tobacco Reporting Regulations were used to examine whole tobacco constituents for 1809 brands and mainstream smoke emissions for 191 brands manufactured by Canada's three leading cigarette companies from 2005 through 2011/12 using one-way analysis of variances (ANOVAs) and linear regression models.
Levels of N-nitrosoanatabine (NAT) (p < .001) and 4-(methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK) (p < .001) in whole tobacco showed significant differences over time, decreasing between 2005 and 2007, and generally increasing from 2007 through 2012. Levels of all TSNAs in mainstream smoke emissions reflected a similar pattern: N-nitrosoanabasine (NAB) (p < .001), NAT (p < .001), NNK (p < .001), and N'-nitrosonornicotine (NNN) (p = .021). Linear regression analyses showed that TSNA levels varied by manufacturer over time in whole tobacco for NAT, NNK, and NNN (p < .001 for all), and in smoke emissions for NAB, NAT, NNK, and NNN (p < .001 for all).
The findings indicate that levels of TSNAs in whole tobacco and smoke emissions of cigarettes sold in Canada increased from 2007 through 2011/12, following initial reductions over the previous 2 years. Differences in TSNA levels between companies raise questions about manufacturing practices that may be responsible for these changes. Although increased levels of carcinogenic TSNAs may be alarming, it remains unclear whether these differences translate into differences in health risk.
The wide variation of TSNAs within the Canadian market across time and across cigarette companies demonstrates the feasibility of reducing the levels of these potent carcinogens. Although it is unclear whether changes made to levels of TSNAs will result in less tobacco-related disease, the tobacco industry bears a responsibility to minimize the harm from smoking to the fullest extent possible.
烟草特异性亚硝胺（TSNAs）是强致癌物质。通过制造工艺可以改变 TSNAs 的含量。21 世纪初，加拿大通过改变烟草烘烤工艺降低了销售卷烟中的 TSNAs 含量。本研究在接下来的十年中检测 TSNAs 水平，以研究随时间的变化趋势。
通过《烟草报告法规》向加拿大卫生部提交的数据，利用方差分析（ANOVA）和线性回归模型，研究了加拿大三家主要卷烟公司在 2005 年至 2011/12 年间生产的 1809 个品牌的全烟草成分和 191 个品牌的主流烟雾排放物中的 TSNAs 水平。
全烟草中 N-亚硝基降烟碱（NAT）（p <.001）和 4-（甲基亚硝氨基）-1-（3-吡啶基）-1-丁酮（NNK）（p <.001）水平随时间显著变化，2005 年至 2007 年下降，2007 年至 2012 年普遍上升。主流烟雾排放物中所有 TSNAs 的水平反映出类似的模式：N-亚硝基降烟碱（NAB）（p <.001）、NAT（p <.001）、NNK（p <.001）和 N'-亚硝基降烟碱（NNN）（p =.021）。线性回归分析表明，全烟草中 NAT、NNK 和 NNN 的制造商随时间推移而变化（所有 p <.001），以及烟排放物中的 NAB、NAT、NNK 和 NNN（所有 p <.001）。
研究结果表明，2007 年至 2011/12 年间，加拿大销售卷烟中的全烟草和烟雾排放物中的 TSNAs 水平呈上升趋势，此前两年的初始降幅有所下降。公司之间 TSNAs 水平的差异引发了人们对可能导致这些变化的制造实践的质疑。虽然致癌性 TSNAs 水平的增加可能令人担忧，但尚不清楚这些差异是否转化为健康风险的差异。
加拿大市场在时间和卷烟公司之间的 TSNAs 广泛变化表明，降低这些强致癌物质水平是可行的。尽管尚不清楚对 TSNAs 水平的改变是否会导致与烟草相关的疾病减少，但烟草行业有责任尽可能最大限度地减少吸烟造成的危害。
