Levels of selected analytes in the emissions of "heat not burn" tobacco products that are relevant to assess human health risks.

Consumers of combustible cigarettes are exposed to many different toxicologically relevant substances associated with negative health effects. Newly developed "heat not burn" (HNB) devices are able to contain lower levels of Harmful and Potentially Harmful Constituents (HPHCs) in their emissions compared to tobacco cigarettes. However, to develop toxicological risk assessment strategies, further independent and standardized investigations addressing HPHC reduction need to be done. Therefore, we generated emissions of a commercially available HNB product following the Health Canada Intense smoking regimen and analyzed total particulate matter (TPM), nicotine, water, aldehydes, and other volatile organic compounds (VOCs) that are major contributors to health risk. We show that nicotine yield is comparable to typical combustible cigarettes, and observe substantially reduced levels of aldehydes (approximately 80-95%) and VOCs (approximately 97-99%). Emissions of TPM and nicotine were found to be inconsistent during the smoking procedure. Our study confirms that levels of major carcinogens are markedly reduced in the emissions of the analyzed HNB product in relation to the conventional tobacco cigarettes and that monitoring these emissions using standardized machine smoking procedures generates reliable and reproducible data which provide a useful basis to assess exposure and human health risks.

HT-2 toxin 4-glucuronide as new T-2 toxin metabolite: enzymatic synthesis, analysis, and species specific formation of T-2 and HT-2 toxin glucuronides by rat, mouse, pig, and human liver microsomes.

Glucuronides of the mycotoxin T-2 toxin and its phase I metabolite HT-2 toxin are important phase II metabolites under in vivo and in vitro conditions. Since standard substances are essential for the direct quantitation of these glucuronides, a method for the enzymatic synthesis of T-2 and HT-2 toxin glucuronides employing liver microsomes was optimized. Structure elucidation by nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry revealed that besides T-2 toxin glucuronide and HT-2 toxin 3-glucuronide also the newly identified isomer HT-2 toxin 4-glucuronide was formed. Glucuronidation of T-2 and HT-2 toxin in liver microsomes of rat, mouse, pig, and human was compared and metabolites were analyzed directly by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). A distinct, species specific pattern of glucuronidation of T-2 and HT-2 toxin was observed with interesting interindividual differences. Until recently, glucuronides have frequently been analyzed indirectly by quantitation of the aglycone after enzymatic cleavage of the glucuronides by ß-glucuronidase. Therefore, the hydrolysis efficiencies of T-2 and HT-2 toxin glucuronides using ß-glucuronidases from Helix pomatia, bovine liver, and Escherichia coli were compared.

Identification and apoptotic potential of T-2 toxin metabolites in human cells.

The mycotoxin T-2 toxin, produced by various Fusarium species, is a widespread contaminant of grain and grain products. Knowledge about its toxicity and metabolism in the human body is crucial for any risk assessment as T-2 toxin can be detected in processed and unprocessed food samples. Cell culture studies using cells of human origin represent a potent model system to study the metabolic fate of T-2 toxin as well as the cytotoxicity in vitro. In this study the metabolism of T-2 toxin was analyzed in a cell line derived from human colon carcinoma cells (HT-29) and primary human renal proximal tubule epithelial cells (RPTEC) using high-performance liquid chromatography coupled with Fourier transformation mass spectrometry (HPLC-FTMS). Both cell types metabolized T-2 toxin to a variety of compounds. Furthermore, cell cycle analysis in RPTEC proved the apoptotic effect of T-2 toxin and its metabolites HT-2 toxin and neosolaniol in micromolar concentrations.

Intestinal metabolism of T-2 toxin in the pig cecum model.

T-2 toxin, a toxic member of the group A trichothecenes, is produced by various Fusarium species that can potentially affect human health. As the intestine plays an important role in the metabolism of T-2 toxin for animals and humans, the degradation and metabolism of T-2 toxin was studied using the pig cecum in vitro model system developed in the author's group. In order to study the intestinal degradation of T-2 toxin by pig microbiota, incubation was performed with the cecal chyme from four different pigs in repeat determinations. A large variation in the intestinal degradation of T-2 toxin was observed for individual pigs. T-2 toxin was degraded almost completely in one out of four pigs, in which only 3.0 ± 0.1 % of T-2 toxin was left after 24 h incubation. However, in the other three incubations with pig cecal suspension, 54.1 ± 11.7-68.9 ± 16.1 % of T-2 toxin were still detectable after 24 h incubation time. The amount of HT-2 toxin was increased along with the incubation time, and HT-2 toxin accounted for 85.2 ± 0.7 % after 24 h in the most active cecum. HT-2 toxin was the only detectable metabolite formed by the intestinal bacteria. This study suggests that the toxicity of T-2 toxin for pigs is caused by the combination of T-2 and HT-2 toxins.