Exposure characteristics and risk assessment of VOCs from Chinese residential cooking.

In comparison with various restaurant cuisines, common cooking methods are more represented in residential cooking. Rather than the exhaust pipe or the ambient environment in the cooking room, the respiration zone better reflects the health risks for operators. In this study, the concentrations of total volatile organic compound (TVOC) released from six typical cooking methods were monitored online in the respiratory zone, and the VOCs were analysed by GC-MS. The results demonstrated that the intensities of exposure to TVOC for the different cooking methods decreased as follows: stir-frying (3.809 mg/m3) > quick-frying (2.724 mg/m3) > deep-frying (2.465 mg/m3) > boiling (1.161 mg/m3)≈stewing (1.149 mg/m3) > limit in China (0.600 mg/m3) > steaming (0.440 mg/m3). The intense ventilation mode of the ventilator reduced exposure to TVOC by 45-63% relative to the medium mode. Eleven types of VOCs (approximately 200 compounds) were found in Chinese residential cooking fumes, and the predominant contaminants were aldehydes, followed by alkanes, unsaturated aldehydes, alcohols and alkenes. The mass percentage of aromatic hydrocarbons in all VOCs emitted from Chinese residential cooking was only 1%, while the value was 17-48% for commercial restaurants. The results of a health risk assessment revealed that the total potential carcinogenic risk level for VOCs released by six residential cooking methods decreased as follows: deep-frying (5.75) > stir-frying (3.95) > quick-frying (2.94) > stewing (1.99) > boiling (1.73) > steaming (1.48). Chinese residential cooking, and especially deep frying, has potential health impacts for the operator.

The Emission of VOCs and CO from Heated Tobacco Products, Electronic Cigarettes, and Conventional Cigarettes, and Their Health Risk.

The differences in aerosol composition between new tobacco types (heated tobacco products and electronic cigarettes) and conventional cigarettes have not been systematically studied. In this study, the emissions of volatile organic compounds (VOCs), carbon monoxide (CO), nicotine, and tar from heated tobacco products (HTPs), electronic cigarettes (e-cigarettes) and conventional cigarettes were compared, and their health risks were evaluated by applying the same smoking regime and a loss mechanism of smoking. Twenty VOCs were identified in aerosols from HTPs, 18 VOCs were identified in aerosols from e-cigarettes, and 97 VOCs were identified in aerosols from cigarettes by GC-MS and HPLC analysis. The concentrations of total VOCs (TVOCs) emitted by the three types of tobacco products decreased as follows: e-cigarettes (795.4 mg/100 puffs) > cigarettes (83.29 mg/100 puffs) > HTPs (15.65 mg/100 puffs). The nicotine content was 24.63 ± 2.25 mg/100 puffs for e-cigarettes, 22.94 ± 0.03 mg/100 puffs for cigarettes, and 8.817 ± 0.500 mg/100 puffs for HTPs. When using cigarettes of the same brand, the mass concentrations of VOCs, tar, and CO emitted by HTPs were approximately 81.2%, 95.9%, and 97.5%, respectively, lower than the amounts emitted by cigarettes. The health risk results demonstrated that the noncarcinogenic risk of the three types of tobacco products decreased as follows: cigarettes (3609.05) > HTPs (2449.70) > acceptable level (1) > e-cigarettes (0.91). The lifetime cancer risk (LCR) decreased as follows: cigarettes (2.99 × 10-4) > HTPs (9.92 × 10-5) > e-cigarettes (4.80 × 10-5) > acceptable level (10-6). In general, HTPs and e-cigarettes were less harmful than cigarettes when the emission of VOCs and CO was considered.

Mn-based catalysts supported on γ-Al2O3, TiO2 and MCM-41: a comparison for low-temperature NO oxidation with low ratio of O3/NO.

Mn-Based catalysts supported on γ-Al2O3, TiO2 and MCM-41 synthesized by an impregnation method were compared to evaluate their NO catalytic oxidation performance with low ratio O3/NO at low temperature (80-200 °C). Activity tests showed that the participation of O3 remarkably promoted the NO oxidation. The catalytic oxidation performance of the three catalysts decreased in the following order: Mn/γ-Al2O3 > Mn/TiO2 > Mn/MCM-41, indicating that Mn/γ-Al2O3 exhibited the best catalytic activity. In addition, there was a clear synergistic effect between Mn/γ-Al2O3 and O3, followed by Mn/TiO2 and O3. The characterization results of XRD, EDS mapping, BET, H2-TPR, XPS and TG showed that Mn/γ-Al2O3 had good manganese dispersion, excellent redox properties, appropriate amounts of coexisting Mn3+ and Mn4+ and abundant chemically adsorbed oxygen, which ensured its good performance. In situ DRIFTS demonstrated the NO adsorption performance on the catalyst surface. As revealed by in situ DRIFTS experiments, the chemically adsorbed oxygen, mainly from the decomposition of O3, greatly promoted the NO adsorption and the formation of nitrates. The Mn-based catalysts showed stronger adsorption strength than the corresponding pure supports. Due to the abundant adsorption sites provided by pure γ-Al2O3, under the interaction of Mn and γ-Al2O3, the Mn/γ-Al2O3 catalyst exhibited the strongest NO adsorption performance among the three catalysts and produced lots of monodentate nitrates (-O-NO2) and bidentate nitrates (-O2NO), which were the vital intermediate species for NO2 formation. Moreover, the NO-TPD studies also demonstrated that Mn/γ-Al2O3 showed the best NO desorption performance among the three catalysts. The good NO adsorption and desorption characteristics of Mn/γ-Al2O3 improved its high catalytic activity. In addition, the activity test results also suggested that Mn/γ-Al2O3 exhibited good SO2 tolerance.

The emission characteristic of VOCs and the toxicity of BTEX from different mosquito-repellent incenses.

Three types of mosquito-repellent incenses including disc, electric liquid and electric mat, were selected to investigate the emission of volatile organic compounds in the respiratory zone during the burning. VOCs were analyzed by GC-MS. Results showed that the average concentration of TVOCs released by using the disc, electric liquid and electric mat mosquito repellent incense types were 7.760 ±â€¯4.724, 3.122 ±â€¯0.866 and 1.192 ±â€¯0.062 mg/m3, respectively. The TVOCs pollution level produced during the burning of different mosquito-repellent incense types was ranked in the order: disc > electric liquid > electric mat. The concentration of TVOCs produced by Q-liquid, L-liquid, Q-disc and L-disc mosquito-repellent incense types could cause discomfort to the human body. Other types of mosquito-repellent incense induced multiple synergistic effects on human response. About 230 kinds of VOCs including 14 types of VOCs, were found in the smoke of mosquito-repellent incense. The number and content of alkanes was the highest, followed by aromatic hydrocarbons and esters. The level of non-carcinogenic health risk presented by exposure to BTEX (toluene, xylene and ethylbenzene) was acceptable. The chronic daily intake of VOCs decreased with age for both males and females, with male exposure being higher than that of the female, except for children.

The emission of PM2.5 in respiratory zone from Chinese family cooking and its health effect.

To investigate the PM2.5 emission in the direct exposed area from Chinese family cooking, eleven kinds of Chinese ordinary family cooking dishes were designed including frying, quick-frying, stewing, deep-frying, boiling and steaming according to the results of questionnaire survey. The results showed that the intensity sequence for PM2.5 emissions decreased as follows in general: deep-frying (0.709-2.731 mg/m3) > stir-frying (0.700-0.958 mg/m3) > stewing (~0.573 mg/m3) > quick-frying (0.140-0.433 mg/m3) > boiling (0.004-0.247 mg/m3) > steaming (0.011-0.088 mg/m3), most of them exceeded the national indoor air standard. The average concentration of PM2.5 in the direct respiratory zone from family cooking was determined to be 0.599 mg/m3, which was about 8 times higher than the national indoor air standard of China and lower than that from commercial restaurants. The annual PM2.5 inhalation exposure in the direct exposed area from family cooking for male and female was 346.30 mg/year and 309.59 mg/year, respectively. Although the annual PM2.5 inhalation exposure of male operators in general ordinary family cooking was about 11.8% higher than that of females, the pregnant women, children and the elderly are not encouraged to prepare ordinary family cooking for a long time due to their sensitive to PM2.5 emission. Selecting ventilator with high wind speed can reduce PM2.5 emission more than 65% when compared to medium wind speed. Improvement of ventilator wind speed is considered to be an effect way to reduce PM2.5 emission for cooking.

Synthesis of jaspaquinol and effect on viability of normal and malignant bladder epithelial cell lines.

The synthesis of jaspaquinol 1, a monocyclic diterpene-benzenoid, is reported. Two synthetic routes to this natural product have been developed. The first, utilises a difunctional terpene derivative containing different leaving groups, facilitating the selective introduction of the cyclohexenyl and benzenoid fragments. The alternative route employs a regiospecific Stille cross-coupling reaction to introduce the cyclohexenyl fragment, which occurs without allylic transposition. Preliminary data shows the cell viability of 1 against normal and malignant human bladder epithelial cell lines.

2-pyrones possessing antimicrobial and cytotoxic activities.

The 2-pyrone sub-unit is found in a number of natural products possessing broad spectrum biological activity. Such compounds are validated as being capable of binding to specific protein domains and able to exert a remarkable range of biological effects. In an effort to identify synthetic 2-pyrones with interesting biological effects, herein we report the synthesis and biological evaluation of 4-substituted-6-methyl-2-pyrones. Synthetic routes to 4-alkyl/alkenyl/aryl/alkynyl-6-methyl-2-pyrones have been developed utilising Sonogashira, Suzuki and Negishi cross-coupling starting from readily available 4-bromo-6-methyl-2-pyrone. Specific conditions for each organometallic protocol were required for successful cross-coupling. In particular, a triethylamine/acetonitrile--base/solvent mixture was crucial to Sonogashira alkynylation of 4-bromo-6-methyl-2-pyrone, whereas thallium carbonate was a mandatory base for the Suzuki cross-coupling of trialkylboranes. The 2-pyrones demonstrate potent inhibitory activity against Bacillus subtilis, Escherichia coli, Staphylococcus aureus, Schizosaccharomyces pombe and Botrytis cinerea. The growth inhibitory activities of selected 2-pyrones were determined in A2780 human ovarian carcinoma and K562 human chronic myelogenous leukaemia cell lines using an in vitro cell culture system (MTT assay). These studies demonstrate that 4-phenylethynyl-, 4-tetrahydropyranylpropargyl ether- and 4-ethynyl-6-methyl-2-pyrones have excellent potential as a new class of anticancer agents.