The use of charcoal in modified cigarette filters for mainstream smoke carbonyl reduction

Measurement of harmful nanoparticle distribution among filters, smokers' respiratory systems, and surrounding air during cigarette smoking

This study was undertaken to investigate the filtration effect of filter on nanoparticle and the deposition behavior of nanoparticle in the human respiratory system from the aspect of nanoparticle number during cigarette smoking. For that, two kinds of experiments were designed. One is machine experiment, a well-controlled simulated respiratory system was designed to measure the raw emission and filter effect. Another is human experiment, volunteers were asked to inhale smoke into the oral cavity only and lungs, respectively, to distinguish smoke path. Results revealed that effective inhaled nanoparticle amount of a Taishan and a Hongtaishan cigarette were 5.8E + 9 (#) and 9.4E + 7 (#), respectively. The filter's integrated reduction rate was 41.65% for nanoparticle. For Taishan cigarette, 35.4% and 41.7% of raw emitted nanoparticles were deposited in the oral cavity and lungs, respectively, the rest of 22.9% was exhaled to surrounding air. The corresponding values were 25.6%, 41.5% and 32.9%, respectively, for Hongtaishan. The current findings are expected to provide basic assessments of filter effect and harm to human and to be a warning for smokers.

Effects of Charcoal on Carbonyl Delivery from Commercial, Research, and Make-Your-Own Cigarettes

Previous literature has shown that adding charcoal to cigarette filters can have varying effects on the delivery of toxic carbonyls depending on filter design, amount of charcoal, and puffing profiles. However, these studies have relied on either comparisons between commercially available charcoal and noncharcoal filtered cigarettes or experimental modification of filters to insert a charcoal plug into existing cellulose acetate filters. Make-your-own (MYO) cigarettes can help obviate many of the potential pitfalls of previous studies; thus, we conducted studies using commercial charcoal cigarettes and MYO cigarettes to determine the effects of charcoal on carbonyl delivery. To do this, we analyzed carbonyls in mainstream smoke by HPLC-UV after derivatization with 2,4-dinitrophenylhydrazine (DNPH). Charcoal was added in-line after the cigarettes or through the use of MYO charcoal cigarette tubes. MYO cigarettes had carbonyl deliveries similar to that of 3R4F research cigarette, regardless of tobacco type. The greatest effect on carbonyl delivery was observed with 200 mg of charcoal, significantly reducing all carbonyls under both methods tested. However, "on-tow" design charcoal filters, available on many commercially available charcoal brands, appeared to have a minimal effect on carbonyl delivery under intense smoking methods. Overall, we found that charcoal, when added in sufficient quantity (200 mg) as a plug, can substantially reduce carbonyl delivery for both MYO and conventional cigarettes. As carbonyls are related to negative health outcomes, such reductions may be associated with reductions in carbonyl-related harm in smokers.

Effect of Charcoal in Cigarette Filters on Free Radicals in Mainstream Smoke

The addition of charcoal in cigarette filters may be an effective means of reducing many toxicants from tobacco smoke. Free radicals are a highly reactive class of oxidants abundant in cigarette smoke, and here we evaluated the effectiveness of charcoal to reduce free radical delivery by comparing radical yields from commercially available cigarettes with charcoal-infused filters to those without and by examining the effects of incorporating charcoal into conventional cigarette filters on radical production. Commercial cigarettes containing charcoal filters produced 40% fewer gas-phase radicals than did regular cellulose acetate filter cigarettes when smoked using the International Organization of Standardization (ISO, p = 0.07) and Canadian Intense (CI, p < 0.01) smoking protocols. While mean-particulate-phase radicals were 25-27% lower in charcoal cigarettes, differences from noncharcoal products were not significant ( p = 0.06-0.22). When cellulose acetate cigarette filters were modified to incorporate different types and amounts of activated charcoal, reductions in gas-phase (>70%), but not particulate-phase, radicals were observed. The reductions in gas-phase radicals were similar for the three types of charcoal. Decreases in radical production were dose-responsive with increasing amounts of charcoal (25-300 mg) with as little as 25 mg of activated charcoal reducing gas-phase radicals by 41%. In all studies, charcoal had less of an effect on nicotine delivery, which was decreased 33% at the maximal amount of charcoal tested (300 mg). Overall, these results support the potential consideration of charcoal in cigarette filters as a means to reduce exposure to toxic free radicals from cigarettes and other combustible tobacco products.