Insights from a multi-year program designed to test the impact of ingredients on mainstream cigarette smoke toxicity

Impact assessment of WHO TobReg proposals for mandated lowering of selected mainstream cigarette smoke toxicants

The WHO Tobacco Product Regulation Study Group (TobReg) has proposed three regulatory models for cigarettes, each creating mandatory limits for emissions of nine smoke toxicants. One approach proposes country-specific limits, using median or 1.25× median toxicant/nicotine emission ratios. A second model provides fixed toxicant-ratio limits. The third model limits were three times the lowest toxicant emission on a market. Currently, the practical implications of these models are largely unknown. An impact assessment was conducted using cigarette data from 79 countries to identify four diverse test markets. We sampled all products from each market but limited product availability led to incomplete (80-97%) sourcing. Analysis showed that the country-specific model led to diverse (up to threefold) toxicant limits across the four markets. 70%-80% of products were non-compliant, rising to 100% in some countries with the second and the third models. With each regulatory model the main drivers of non-compliance were the tobacco-specific nitrosamines, the simultaneous application of limits for nine poorly correlated smoke toxicants, and analytical variability. Use of nicotine ratios led to compliance of some high toxicant emission products due to high nicotine emissions. Our findings suggest that these proposals would have greater impact on global markets than TobReg's stated aims.

Insights from analysis for harmful and potentially harmful constituents (HPHCs) in tobacco products

A total of 20 commercial cigarette and 16 commercial smokeless tobacco products were assayed for 96 compounds listed as harmful and potentially harmful constituents (HPHCs) by the US Food and Drug Administration. For each product, a single lot was used for all testing. Both International Organization for Standardization and Health Canada smoking regimens were used for cigarette testing. For those HPHCs detected, measured levels were consistent with levels reported in the literature, however substantial assay variability (measured as average relative standard deviation) was found for most results. Using an abbreviated list of HPHCs, statistically significant differences for most of these HPHCs occurred when results were obtained 4-6months apart (i.e., temporal variability). The assay variability and temporal variability demonstrate the need for standardized analytical methods with defined repeatability and reproducibility for each HPHC using certified reference standards. Temporal variability also means that simple conventional comparisons, such as two-sample t-tests, are inappropriate for comparing products tested at different points in time from the same laboratory or from different laboratories. Until capable laboratories use standardized assays with established repeatability, reproducibility, and certified reference standards, the resulting HPHC data will be unreliable for product comparisons or other decision making in regulatory science.

A comprehensive evaluation of selected components and processes used in the manufacture of cigarettes: approach and overview

CONTEXT

In addition to tobacco and cigarette ingredients, there are many non-tobacco components and processes used to manufacture commercial cigarettes. Proposed cigarette components and manufacturing process changes were evaluated using a tiered toxicological testing program.

OBJECTIVE

The toxicological testing and evaluation of proposed changes to selected non-tobacco cigarette components and manufacturing processes are described in this special report.

MATERIALS AND METHODS

Selected non-tobacco cigarette components and manufacturing processes were evaluated using experimental and control cigarettes. These experimental cigarettes were evaluated using mainstream smoke chemistry, bacterial mutagenicity and cytotoxicity assays. In some evaluations, 90-day nose-only mainstream smoke inhalation studies using rats were performed.

RESULTS

Some proposed design changes were not implemented, or limitations on their use were established. Most study results, however, were similar to those previously reported in the scientific literature for design changes in cigarette construction.

CONCLUSION

The studies reported in the series of publication demonstrate that our testing approach is feasible for evaluation of cigarette component and manufacturing process changes.

A comprehensive evaluation of the toxicology resulting from laser-generated ventilation holes in cigarette filters

CONTEXT

Recent technological advances allow ventilation holes in (or adjacent to) cigarette filters to be produced using lasers instead of using the mechanical procedures of earlier techniques.

OBJECTIVE

Analytical chemistry can be used to compare the composition of mainstream smoke from experimental cigarettes having filters with mechanically produced ventilation holes to that of cigarettes with ventilation holes that were produced using laser technology.

MATERIALS AND METHODS

Established procedures were used to analyze the smoke composition of 38 constituents of mainstream smoke generated using standard conditions.

RESULTS

There were no differences between the smoke composition of cigarettes with filter ventilation holes that were produced mechanically or through use of laser technology.

CONCLUSION

The two methods for producing ventilation holes in cigarette filters are equivalent in terms of resulting mainstream smoke chemistry, at two quite different filter ventilation percentages.

Discriminatory power of standard toxicity assays used to evaluate ingredients added to cigarettes

A tiered approach for testing ingredients in a cigarette matrix was developed and includes chemical-analytical testing and a standard battery of biological toxicity assays. These assays were adapted for comparative evaluation of mainstream smoke from experimental cigarettes with or without ingredients at various inclusion levels. This adaptation to test cigarette mainstream smoke may impact assay response. Since it is difficult to a priori determine discriminatory power, it was evaluated using a large experimental dataset from a multi-year program of cigarette ingredient testing performed at two separate laboratories. A statistical method, minimum detectable difference (MDD), was used as a measure of assay discriminatory power. MDD of cigarette smoke constituents ranged from 6% to 29% of the average. Salmonella mutagenicity and cytotoxicity test MDDs ranged from 20% to 81% and 18% to 49%, respectively. Body weight gain in 90-day nose-only inhalation studies yielded an MDD of 30-40%. Histopathological findings with severity scores between 0.5 and 1.5 had the lowest MDDs of 23% and higher. In general, discriminatory power decreased with increasing biological complexity and toxicological relevance of the assay. Beyond statistical analysis, however, a weight-of-the-evidence analysis by experienced researchers is required for toxicological assessment of a cigarette ingredient.