Regulatory toxicology and pharmacology : RTP
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Regul. Toxicol. Pharmacol. · Nov 2016
Comparative StudyEvaluation of the Tobacco Heating System 2.2. Part 2: Chemical composition, genotoxicity, cytotoxicity, and physical properties of the aerosol.
The chemical composition, in vitro genotoxicity, and cytotoxicity of the mainstream aerosol from the Tobacco Heating System 2.2 (THS2.2) were compared with those of the mainstream smoke from the 3R4F reference cigarette. In contrast to the 3R4F, the tobacco plug in the THS2.2 is not burnt. The low operating temperature of THS2.2 caused distinct shifts in the aerosol composition compared with 3R4F. ⋯ The chemical composition of the THS2.2 aerosol was also evaluated under extreme climatic and puffing conditions. When generating the THS2.2 aerosol under "desert" or "tropical" conditions, the generation of HPHCs was not significantly modified. When using puffing regimens that were more intense than the standard Health Canada Intense (HCI) machine-smoking conditions, the HPHC yields remained lower than when smoking the 3R4F reference cigarette with the HCI regimen.
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Regul. Toxicol. Pharmacol. · Nov 2016
Comparative StudyEvaluation of the Tobacco Heating System 2.2. Part 4: 90-day OECD 413 rat inhalation study with systems toxicology endpoints demonstrates reduced exposure effects compared with cigarette smoke.
The objective of the study was to characterize the toxicity from sub-chronic inhalation of test atmospheres from the candidate modified risk tobacco product (MRTP), Tobacco Heating System version 2.2 (THS2.2), and to compare it with that of the 3R4F reference cigarette. A 90-day nose-only inhalation study on Sprague-Dawley rats was performed, combining classical and systems toxicology approaches. Reduction in respiratory minute volume, degree of lung inflammation, and histopathological findings in the respiratory tract organs were significantly less pronounced in THS2.2-exposed groups compared with 3R4F-exposed groups. ⋯ Most other toxicological endpoints evaluated did not show exposure-related effects. Where findings were observed, the effects were similar in 3R4F- and THS2.2-exposed animals. In summary, toxicological changes observed in the respiratory tract organs of THS2.2 aerosol-exposed rats were much less pronounced than in 3R4F-exposed rats while other toxicological endpoints either showed no exposure-related effects or were comparable to what was observed in the 3R4F-exposed rats.
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Regul. Toxicol. Pharmacol. · Nov 2016
Randomized Controlled Trial Comparative StudyAssessment of the reduction in levels of exposure to harmful and potentially harmful constituents in Japanese subjects using a novel tobacco heating system compared with conventional cigarettes and smoking abstinence: A randomized controlled study in confinement.
Smoking conventional cigarettes (CCs) exposes smokers to harmful and potentially harmful constituents (HPHCs). The Tobacco Heating System 2.2 (THS 2.2), a candidate modified risk tobacco product, was developed to reduce or eliminate the formation of HPHCs, while preserving as much as possible the taste, sensory experience, nicotine delivery profile and ritual characteristics of CC. This randomized, controlled, open-label study in confinement for 5 day exposure aimed to demonstrate the reduction in exposure to selected HPHCs, to assess nicotine uptake and subjective effects, in participants switching to THS 2.2 (n = 80) compared to participants continuing smoking CCs (n = 40) and abstaining from smoking (n = 40). ⋯ More importantly, the magnitude of exposure reduction observed was close to that which was seen in participants who abstained from smoking for 5 days, while nicotine uptake was maintained. Reduction in urge-to-smoke was comparable between THS and CC groups, however THS 2.2 was slightly less satisfactory than CCs. The new, alternative tobacco product THS 2.2 was well tolerated.
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Regul. Toxicol. Pharmacol. · Oct 2016
Meta AnalysisAcute inhalation toxicity of carbon monoxide and hydrogen cyanide revisited: Comparison of models to disentangle the concentration × time conundrum of lethality and incapacitation.
Contemporary emergency response planning guidelines are stratified to consider the threshold for serious toxicity and/or impairment of escape, relative to the potentially lethal level above this threshold and the lower level at which individuals should not experience or develop effects more serious than mild irritation. While harmonized testing guidelines and risk assessment paradigms are available for the quantification of thresholds for lethality or establishing no adverse effect levels, the quantification of 'impairment of escape' appears to be a more elusive goal. Approaches were explored in context with CO and HCN in past experimental combustion toxicology studies to estimate the time available for escape. ⋯ No specific modeled carboxyhemoglobin (COHb) level could be linked to onset of incapacitation. In summary, the higher ventilation of rats (kg body weight adjusted) renders this species even more susceptible than heavy breathing humans. LCt01 × 1/3 values derived from the comprehensive Cxt matrix of rat inhalation studies are considered to be most suitable and robust to estimate the human equivalent threshold (POD) of 'impairment of escape'.
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Generally Recognized as Safe (GRAS) substances are exempt from premarket approval; however, the standard of "reasonable certainty of no harm" is the same. In 1997, the voluntary GRAS affirmation process was replaced with the voluntary U. S. ⋯ Only four raised questions about potential safety, of which three received a no questions letter upon providing more data. Of the 84 withdrawn notices, 22 received a no questions letter upon resubmission. In spite of criticisms, the FDA GRAS notice process is clearly defined, efficient, and cost-effective, and there have been no known public health issues following its implementation.