Valavanidis A, Haralambous E. A comparative study by electron paramagnetic resonance of free radical species in the mainstream and sidestream smoke of cigarettes with conventional acetate filters and bio-filters. Redox Report 2001; 6: 161–171

Abstract

I am very sceptical of the research described in this article. The authors aim for a comparison of the free radical species in the mainstream and sidestream smoke of cigarettes containing conventional acetate with those containing a bio-filter using electron paramagnetic resonance (EPR) methodology. In my opinion, the interpretation of their results is totally invalid since it was not based on basic scientific principles. The first very important issue to mention about this work is that the complexity of tobacco smoke is such that the type of tobacco is of crucial importance when the efficacy of different types of filter is compared. In this study, the authors compared a total number of four different cigarettes (each containing a different type of tobacco), three of which contained conventional acetate filters and one contained a bio-filter. Therefore, the reported data concerning the efficiency of the filters used cannot possibly be compared and any such attempt will be inaccurate. According to the experimental data presented in the paper, the cigarette containing the bio-filter has the same mainstream tar radical species with the same intensity EPR signals to those of the cigarettes with the conventional acetate filter. In terms of the ability of the aqueous cigarette tar extracts to produce hydroxyl radicals, again, the results were the same for all cigarettes. However, in the gas phase of mainstream smoke, the cigarette containing the bio-filter showed 30‐ 35% less production of oxygen-centered radicals than the rest of the cigarettes with the conventional acetate filter. These findings were in agreement with the reported findings showing that the bio-filter reduces significantly the levels of isoprene and many other constituents of the gas phase of cigarette