Aldehyde emissions from wood-burning fireplaces

Aqueous-Phase Photoreactions of Mixed Aromatic Carbonyl Photosensitizers Yield More Oxygenated, Oxidized, and less Light-Absorbing Secondary Organic Aerosol (SOA) than Single Systems

Aromatic carbonyls have been mainly probed as photosensitizers for aqueous secondary organic aerosol (aqSOA) and light-absorbing organic aerosol (i.e., brown carbon or BrC) formation, but due to their organic nature, they can also undergo oxidation to form aqSOA and BrC. However, photochemical transformations of aromatic carbonyl photosensitizers, particularly in multicomponent systems, are understudied. This study explored aqSOA formation from the irradiation of aromatic carbonyl photosensitizers in mixed and single systems under cloud/fog conditions. Mixed systems consisting of phenolic carbonyls only (VL + ActSyr + SyrAld: vanillin [VL] + acetosyringone [ActSyr] + syringaldehyde [SyrAld]) and another composed of both nonphenolic and phenolic carbonyls (DMB + ActSyr + SyrAld: 3,4-dimethoxybenzaldehyde [DMB], a nonphenolic carbonyl, + ActSyr + SyrAld) were compared to single systems of VL (VL*) and DMB (DMB*), respectively. In mixed systems, the shorter lifetimes of VL and DMB indicate their diminished capacity to trigger the oxidation of other organic compounds (e.g., guaiacol [GUA], a noncarbonyl phenol). In contrast to the slow decay and minimal photoenhancement for DMB*, the rapid photodegradation and significant photoenhancement for VL* indicate efficient direct photosensitized oxidation (i.e., self-photosensitization). Relative to single systems, the increased oxidant availability promoted functionalization in VL + ActSyr + SyrAld and accelerated the conversion of early generation aqSOA in DMB + ActSyr + SyrAld. Moreover, the increased availability of oxidizable substrates countered by stronger oxidative capacity limited the contribution of mixed systems to aqSOA light absorption. This suggests a weaker radiative effect of BrC from mixed photosensitizer systems than BrC from single photosensitizer systems. Furthermore, more oxygenated and oxidized aqSOA was observed with increasing complexity of the reaction systems (e.g., VL* < VL + ActSyr + SyrAld < VL + ActSyr + SyrAld + GUA). This work offers new insights into aqSOA formation by emphasizing the dual role of organic photosensitizers as oxidant sources and oxidizable substrates.

Quantitative Kinetics of HO2 Reactions with Aldehydes in the Atmosphere: High-Order Dynamic Correlation, Anharmonicity, and Falloff Effects Are All Important

Kinetics provides the fundamental parameters for elucidating sources and sinks of key atmospheric species and for atmospheric modeling more generally. Obtaining quantitative kinetics in the laboratory for the full range of atmospheric temperatures and pressures is quite difficult. Here, we use computational chemistry to obtain quantitative rate constants for the reactions of HO₂ with HCHO, CH₃CHO, and CF₃CHO. First, we calculate the high-pressure-limit rate constants by using a dual-level strategy that combines conventional transition state theory using a high level of electronic structure wave function theory with canonical variational transition state theory including small-curvature tunneling using density functional theory. The wave-function level is beyond-CCSD(T) for HCHO and CCSD(T)-F12a (Level-A) for XCHO (X = CH₃, CF₃), and the density functional (Level-B) is specifically validated for these reactions. Then, we calculate the pressure-dependent rate constants by using system-specific quantum RRK theory (SS-QRRK) and also by an energy-grained master equation. The two treatments of the pressure dependence agree well. We find that the Level-A//Level-B method gives good agreement with CCSDTQ(P)/CBS. We also find that anharmonicity is an important factor that increases the rate constants of all three reactions. We find that the HO₂ + HCHO reaction has a significant dependence on pressure, but the HO₂ + CF₃CHO reaction is almost independent of pressure. Our findings show that the HO₂ + HCHO reaction makes important contribution to the sink for HCHO, and the HO₂ + CF₃CHO reaction is the dominant sink for CF₃CHO in the atmosphere.

Woodsmoke Extracts Cross-Link Proteins and Induce Cornified Envelope Formation without Stimulating Keratinocyte Terminal Differentiation

Air pollution poses a serious risk to human health. To help understand the contribution of smoke from wood burning to the harmfulness of air pollution toward the skin, we studied the effects of liquid smoke, aqueous extracts of wood smoke condensate, a commercially available food flavor additive, in cultured keratinocytes. We report that liquid smoke can react with and cross-link keratinocyte cellular proteins, leading to abnormal cross-linked envelope formation. Instead of inducing genes ordinarily involved in terminal differentiation, liquid smoke induced expression of genes associated with stress responses. When transglutaminase activity was inhibited, liquid smoke still promoted protein cross-linking and envelope formation in keratinocytes. This phenomenon likely results from oxidative stress and protein adducts from aldehydes as either preloading the cells with N-acetylcysteine or reducing the aldehyde content of liquid smoke decreased its ability to promote protein cross-linking and envelope formation. Finally, liquid smoke-induced envelopes were found to have elevated protein content, suggesting oxidative cross-linking and formation of protein adducts might impair barrier function by inducing abnormal incorporation of cellular proteins into envelopes. Since the cross-linked protein envelope provides structural stability to the stratum corneum and serves as a scaffold for the organization of the corneocyte lipid envelope (hydrophobic barrier to the environment), these findings provide new insight into the mechanism by which pro-oxidative air pollutants can impair epidermal function.

Aromatic Carbonyl and Nitro Compounds as Photosensitizers and Their Photophysical Properties in the Tropospheric Aqueous Phase

Secondary organic aerosol formation in the atmospheric aqueous/particulate phase by photosensitized reactions is currently subject to uncertainties. To understand the impact of photosensitized reactions, photophysical and -chemical properties of photosensitizers, kinetic data, and reaction mechanisms of these processes are required. The photophysical properties of acetophenones, benzaldehydes, benzophenones, and naphthalenes were investigated in aqueous solution using laser flash excitation. Quantum yields of excited photosensitizers were determined giving values between 0.06-0.80 at 298 K and pH = 5. Molar absorption coefficients (ε_max(³PS*) = (0.8-13) × 10⁴ L mol^-1 cm^-1), decay rate constants in water (k_1st = (9.4 ± 0.5) × 10² to (2.2 ± 0.1) × 10⁵ s^-1), and quenching rate constants with oxygen (k_q(O₂) = (1.7 ± 0.1-4.4 ± 0.4) × 10⁹ L mol^-1 s^-1) of the excited triplet states were determined at 298 K and pH = 5. Photosensitized reactions of carboxylic acids and alkenes show second-order rate constants in the range of (37 ± 7.0-0.55 ± 0.1) × 10⁴ and (27 ± 5.0-0.04 ± 0.01) × 10⁸ L mol^-1 s^-1. The results show that different compound classes act differently as a photosensitizer and can be a sink for certain organic compounds in the atmospheric aqueous phase.

Temperature- and pressure-dependent rate coefficient measurement for the reaction of CH2OO with CH3CH2CHO

The rate coefficients of the CH₂OO + CH₃CH₂CHO reaction were studied at temperatures and pressures in the range of 283–318 K and 5–200 Torr.

Levels of Volatile Carbonyl Compounds in the Atlantic Rainforest, in the City of Rio de Janeiro

When Europeans arrived in America, the Brazilian Atlantic rainforest covered approximately 1,290,000 km². Now, only 8% of the biome's original vegetation remains. One of the largest areas is Tijuca Forest National Park. In this work, the concentrations of 13 carbonyl compounds in an isolated area inside Tijuca Forest, in an urban park with primary and secondary vegetation (Gericinó Natural Park) and in two typical urban areas (Tijuca District and the city of Nilópolis) were determined. The main compounds were formaldehyde and acetaldehyde. The formaldehyde mean concentrations were 0.98 ± 1.00, 1.27 ± 1.67, 3.09 ± 1.60 and 2.33 ± 2.17 μg m^-3 for Tijuca Forest, Gericinó Natural Park, Tijuca District and the city of Nilópolis, respectively. The mean acetaldehyde concentrations were, for the same locations, 0.93 ± 1.05, 2.94 ± 2.54, 2.78 ± 0.91 and 5.48 ± 1.90 μg m^-3. The results indicate that the compounds measured within the forest are transported from the city and that the trees play an important role in removing air pollutants. In contrast, the Gericinó protected area is heavily affected by urban emissions, and its capacity to dilute or absorb pollutants is low because of the sparse vegetation.

Environmental Aldehyde Sources and the Health Implications of Exposure

Aldehydes, which are present within the air as well as food and beverage sources, are highly reactive molecules that can be cytotoxic, mutagenic, and carcinogenic. To prevent harm from reactive aldehyde exposure, the enzyme aldehyde dehydrogenase 2 (ALDH2) metabolizes reactive aldehydes to a less toxic form. However, the genetic variant of ALDH2, ALDH2*2, significantly reduces the ability to metabolize reactive aldehydes in humans. Therefore, frequent environmental aldehyde exposure, coupled with inefficient aldehyde metabolism, could potentially lead to an increased health risk for diseases such as cancer or cardiovascular disease.Here, we discuss the environmental sources of reactive aldehydes and the potential health implications particularly for those with an ALDH2*2 genetic variant. We also suggest when considering the ALDH2*2 genetic variant the safety limits of reactive aldehyde exposure may have to be reevaluated. Moreover, the ALDH2*2 genetic variant can also be used as an example for how to implement precision medicine in the field of environmental health sciences.

Quantification of 19 Aldehydes in Human Serum by Headspace SPME/GC/High-Resolution Mass Spectrometry

Sources of human aldehyde exposure include food additives, combustion of organic matter (tobacco smoke), water disinfection byproducts via ozonation, and endogenous processes. Aldehydes are potentially carcinogenic and mutagenic, and chronic human aldehyde exposure has raised concerns about potential deleterious health effects. To aid investigations of human aldehyde exposure, we developed a novel method to measure 19 aldehydes released from Schiff base protein adducts in serum using controlled acid hydrolysis, solid-phase microextraction (SPME), gas chromatography (GC), and high-resolution mass spectrometry (HRMS). Aldehydes are released from Schiff base protein adducts through acid hydrolysis, and are quantified in trace amounts (μg/L) using stable isotope dilution. Detection limits range from 0.1 to 50 μg/L, with calibration curves spanning 3 orders of magnitude. The analysis of fortified quality control material over a three-month period showed excellent precision and long-term stability (3-22% CV) for samples stored at -70 °C. The intraday precision is also excellent (CV, 1-10%). The method accuracy ranges from 89 to 108% for all measured aldehydes, except acrolein and crotonaldehyde, two aldehydes present in tobacco smoke; their analysis by this method is not considered robust due in part to their reactivity in vivo. However, results strongly suggest that propanal, butanal, isobutanal, and isopentanal levels in smokers are higher than levels in nonsmokers, and thus may be useful as biomarkers of tobacco smoke exposure. This method will facilitate large epidemiological studies involving aldehyde biomonitoring to examine nonoccupational environmental exposures.

Acute exposure to crotonaldehyde induces dysfunction of immune system in male Wistar rats

Crotonaldehyde is a ubiquitous air pollutant in the environment. It is reported to be harmful to the biosystems in vivo and in vitro. The exposure to crotonaldehyde irritates the mucous membranes and induces edema, hyperemia, cell necrosis, inflammation, and acute respiratory distress syndrome in the lungs. However, the effects of crotonaldehyde on the immune system have not been reported. In the present study, 6-8 weeks old male Wistar rats were exposed to crotonaldehyde by intratracheal instillation at doses of 4, 8, and 16 μL/kg body weight (b.w.). The general damage in the animals was investigated; the cell counting and the biochemical analysis in the peripheral blood were tested. Furthermore, we investigated the functions of alveolar macrophages (AMs), the alterations of the T-lymphocyte subsets, and the cell composition in the bronchoalveolar lavage fluid (BALF). We found that the activities of the animals were changed after exposure to crotonaldehyde, the cellular ratios and the biochemical components in the peripheral blood were altered, the ratio of mononuclear phagocytes decreased, and the ratios of lymphocytes and granulocytes elevated significantly in BALF. Meanwhile, crotonaldehyde altered the ratio of the T-lymphocyte subsets, and the phagocytic rates and indices of AMs increased obviously. In conclusion, crotonaldehyde induces dysfunction of immune system in male Wistar rats.

Acrolein-an α,β-Unsaturated Aldehyde: A Review of Oral Cavity Exposure and Oral Pathology Effects

Acrolein is a highly reactive unsaturated aldehyde widely present in the environment, particularly as a product of tobacco smoke. Our previous studies indicated the adverse consequences of even short-term acrolein exposure and proposed a molecular mechanism of its potential harmful effect on oral cavity keratinocytic cells. In this paper we chose to review the broad spectrum of acrolein sources such as pollution, food, and smoking. Consequently, in this paper we consider a high level of oral exposure to acrolein through these sources and discuss the noxious effects it has on the oral cavity including on salivary quality and contents, oral resistance to oxidative stress, and stress mechanism activation in a variety of oral cells.

Carbonyl compounds in dining areas, kitchens and exhaust streams in restaurants with varying cooking methods in Kaohsiung, Taiwan

Eighteen carbonyl species in C1-C10 were measured in the dining areas, kitchens and exhaust streams of six different restaurant types in Kaohsiung, southern Taiwan. Measured results in the dining areas show that Japanese barbecue (45.06ppb) had the highest total carbonyl concentrations (sum of 18 compounds), followed by Chinese hotpot (38.21ppb), Chinese stir-frying (8.99ppb), Western fast-food (8.22ppb), Chinese-Western mixed style (7.38ppb), and Chinese buffet (3.08ppb), due to their different arrangements for dining and cooking spaces and different cooking methods. On average, low carbon-containing species (C1-C4), e.g., formaldehyde, acetaldehyde, acetone and butyraldehyde were dominant and contributed 55.01%-94.52% of total carbonyls in the dining areas of all restaurants. Meanwhile, Chinese-Western mixed restaurants (45.48ppb) had high total carbonyl concentrations in kitchens mainly because of its small kitchen and poor ventilation. However, high carbon-containing species (C5-C10) such as hexaldehyde, heptaldehyde and nonanaldehyde (16.62%-77.00% of total carbonyls) contributed comparatively with low carbon-containing compounds (23.01%-83.39% of total carbonyls) in kitchens. Furthermore, Chinese stir-frying (132.10ppb), Japanese barbecue (125.62ppb), Western fast-food (122.67ppb), and Chinese buffet (119.96ppb) were the four restaurant types with the highest total carbonyl concentrations in exhaust streams, indicating that stir-frying and grilling are inclined to produce polluted gases. Health risk assessments indicate that Chinese hotpot and Japanese barbecue exceeded the limits of cancer risk (10(-6)) and hazard index (=1), mainly due to high concentrations of formaldehyde. The other four restaurants were below both limits.

Aldehydes in Relation to Air Pollution Sources: A Case Study around the Beijing Olympics

This study was carried out to characterize three aldehydes of health concern (formaldehyde, acetaldehyde, and acrolein) at a central Beijing site in the summer and early fall of 2008 (from June to October). Aldehydes in polluted atmospheres come from both primary and secondary sources, which limits the control strategies for these reactive compounds. Measurements were made before, during, and after the Beijing Olympics to examine whether the dramatic air pollution control measures implemented during the Olympics had an impact on concentrations of the three aldehydes and their underlying primary and secondary sources. Average concentrations of formaldehyde, acetaldehyde and acrolein were 29.3±15.1 μg/m3, 27.1±15.7 μg/m3 and 2.3±1.0 μg/m3, respectively, for the entire period of measurements, all being at the high end of concentration ranges measured in cities around the world in photochemical smog seasons. Formaldehyde and acrolein increased during the pollution control period compared to the pre-Olympic Games, followed the changing pattern of temperature, and were significantly correlated with ozone and with a secondary formation factor identified by principal component analysis (PCA). In contrast, acetaldehyde had a reduction in mean concentration during the Olympic air pollution control period compared to the pre-Olympic period and was significantly correlated with several pollutants emitted from local emission sources (e.g., NO2, CO, and PM2.5). Acetaldehyde was also more strongly associated with primary emission sources including vegetative burning and oil combustion factors identified through the PCA. All three aldehydes were lower during the post-Olympic sampling period compared to the before and during Olympic periods, likely due to seasonal and regional effects. Our findings point to the complexity of source control strategies for secondary pollutants.

Indoor air characterization of various microenvironments in the Arctic. The case of Tromsø, Norway

The present pilot study monitored for the first time volatile organic compounds (VOCs) and aerosols in domestic and occupational microenvironments in the Arctic Region. Differences between the two categories of samples are noted with domestic environments exhibiting higher concentrations of VOCs (total VOCs ranging between 106 and 584 μg m(-3)), while total particulate matter was highest in workplace non-office environments (ranging between 132 and 284 μg m(-3)). The terpenes were the most abundant class of VOCs, while a variety of other compounds exhibited 100% frequency of occurrence (i.e. naphthalene, D5-volatile methyl siloxane). Compared to results from other studies/regions, the concentrations of VOCs are considered as relatively low. Based on the results and the knowledge of the typical characteristics of the Arctic lifestyle, some important sources are identified. As this is the first study that deals with indoor air quality in the coldest region globally, it is expected that it will trigger the interest of Authorities to proceed to more detailed studies.

Development of three stable isotope dilution assays for the quantitation of (E)-2-butenal (crotonaldehyde) in heat-processed edible fats and oils as well as in food

Three stable isotope dilution assays (SIDAs) were developed for the quantitation of (E)-2-butenal (crotonaldehyde) in heat-processed edible fats and oils as well as in food using synthesized [¹³C₄]-crotonaldehyde as internal standard. First, a direct headspace GC-MS method, followed by two indirect methods on the basis of derivatization with either pentafluorophenylhydrazine (GC-MS) or 2,4-dinitrophenylhydrazine (LC-MS/MS), was developed. All methods are also suitable for the quantitation of acrolein using the standard [¹³C₃]-acrolein. Applying these three methods on five different types of fats and oils varying in their fatty acid compositions revealed significantly varying crotonaldehyde concentrations for the different samples, but nearly identical quantitative data for all methods. Formed amounts of crotonaldehyde were dependent not only on the type of oil, e.g., 0.29-0.32 mg/kg of coconut oil or 33.9-34.4 mg/kg of linseed oil after heat-processing for 24 h at 180 °C, but also on the applied temperature and time. The results indicated that the concentration of formed crotonaldehyde seemed to be correlated with the amount of linolenic acid in the oils. Furthermore, the formation of crotonaldehyde was compared to that of its homologue acrolein, demonstrating that acrolein was always present in higher amounts in heat-processed oils, e.g., 12.3 mg of crotonaldehyde/kg of rapeseed oil in comparison to 23.4 mg of acrolein/kg after 24 h at 180 °C. Finally, crotonaldehyde was also quantitated in fried food, revealing concentrations from 12 to 25 μg/kg for potato chips and from 8 to 19 μg/kg for donuts, depending on the oil used.

Ambient acrolein concentrations in coastal, remote, and urban regions in California

Acrolein (2-propenal) is a reactive chemical that is very toxic and has many sources. Acrolein is commonly detected in the atmosphere, but understanding the ambient concentrations of this compound has been hampered by analytical difficulties. The objective of this research was to utilize an analytical method specifically designed for acrolein to determine acrolein concentrations in remote regions. The purpose was to determine the natural background concentrations of acrolein which were simply lacking in the literature. In addition, rural and urban areas were sampled to determine the degree of anthropogenic enrichment in polluted environments. The results from the coastal and remote inland areas suggest that the median natural summertime background of acrolein was near 40 ng/m(3), which was higher than the Environmental Protection Agency's Reference Concentration (RfC) of 20 ng/m(3). Acrolein concentrations in urban areas were approximately 3- to 8-fold higher than background concentrations, which was a lower degree of urban enrichment than expected. The results suggest that additional research is needed to understand the natural background concentrations of acrolein.

A new device for formaldehyde and total aldehydes real-time monitoring

A new sensitive technique for the quantification of formaldehyde (HCHO) and total aldehydes has been developed in order to monitor these compounds, which are known to be involved in air quality issues and to have health impacts. Our approach is based on a colorimetric method where aldehydes are initially stripped from the air into a scrubbing solution by means of a turning coil sampler tube and then derivatised with 3-methylbenzothiazolinone-2-hydrazone in acid media (pH = -0.5). Hence, colourless aldehydes are transformed into blue dyes that are detected by UV-visible spectroscopy at 630 nm. Liquid core waveguide LCW Teflon® AF-2400 tube was used as innovative optical cells providing a HCHO detection limit of 4 pptv for 100 cm optical path with a time resolution of 15 min. This instrument showed good correlation with commonly used techniques for aldehydes analysis such as DNPH derivatisation chromatographic techniques with off-line and on-line samplers, and DOAS techniques (with deviation below 6%) for both indoor and outdoor conditions. This instrument is associated with simplicity and low cost, which is a prerequisite for indoor monitoring.

Acrolein - a pulmonary hazard

Acrolein is a respiratory irritant that can be generated during cooking and is in environmental tobacco smoke. More plentiful in cigarette smoke than polycyclic aromatic hydrocarbons (PAH), acrolein can adduct tumor suppressor p53 (TP53) DNA and may contribute to TP53-mutations in lung cancer. Acrolein is also generated endogenously at sites of injury, and excessive breath levels (sufficient to activate metalloproteinases and increase mucin transcripts) have been detected in asthma and chronic obstructive pulmonary disease (COPD). Because of its reactivity with respiratory-lining fluid or cellular macromolecules, acrolein alters gene regulation, inflammation, mucociliary transport, and alveolar-capillary barrier integrity. In laboratory animals, acute exposures have lead to acute lung injury and pulmonary edema similar to that produced by smoke inhalation whereas lower concentrations have produced bronchial hyperreactivity, excessive mucus production, and alveolar enlargement. Susceptibility to acrolein exposure is associated with differential regulation of cell surface receptor, transcription factor, and ubiquitin-proteasome genes. Consequent to its pathophysiological impact, acrolein contributes to the morbidly and mortality associated with acute lung injury and COPD, and possibly asthma and lung cancer.

Portable formaldehyde monitoring device using porous glass sensor and its applications in indoor air quality studies

We have developed a portable device for formaldehyde monitoring with both high sensitivity and high temporal resolution, and carried out indoor air formaldehyde concentration analysis. The absorbance difference of the sensor element was measured in the monitoring device at regular intervals of, for example, one hour or 30 min, and the result was converted into the formaldehyde concentration. This was possible because we found that the lutidine derivative that was formed as a yellow product of the reaction between 1-phenyl-1,3-butandione and formaldehyde was stable in porous glass for at least six months. We estimated the reaction rate and to be 0.049 min(-1) and the reaction occurred quickly enough for us to monitor hourly changes in the formaldehyde concentration. The detection limit was 5 μg m(-3) h. We achieved hourly formaldehyde monitoring using the developed device under several indoor conditions, and estimated the air exchange rate and formaldehyde adsorption rate, which we adopted as a new term in the mass balance equation for formaldehyde, in one office.

Formaldehyde measurements in residential indoor air using a developed sensor element in the Kanto area of Japan

We undertook this to determine the formaldehyde concentration in Japanese houses and the relationship between formaldehyde levels and the age and temperature of a house using a sensor element that we developed for time-integrated measurements of formaldehyde concentration in actual environments. We evaluated the correlation between the formaldehyde concentration estimated by the dinitrophenylhydrazine (DNPH)-derivatization method and that obtained with our sensor element. We found a linear relationship between the two results indicating that reliable measurements can be performed using the developed sensor element in actual environments. The indoor concentration of formaldehyde was determined in a study of 34 homes in the Kanto area of Japan, between September 28 and October 27, 2007. We obtained the highest formaldehyde concentrations of 92 ± 15 μg/m(3) for apartments 0-2 years after their renovation, and a simple linear relationship was found between formaldehyde concentration and the age of the apartment. We also found that the formaldehyde concentration in a room containing furniture increased by 10% when the temperature increased by 1°C.

PRACTICAL IMPLICATIONS

This study contributed to the measurements of indoor formaldehyde levels. We have used a newly developed sensor for time-integrated measurements of formaldehyde concentrations. This sensor does not need a power supply during exposure to air, and does not need special skills to use. This research showed that homeowners successfully deployed the sensor at the desired place and desired period in their house by themselves. Formaldehyde is emitted by various off-gassing sources, such as furniture. Therefore, for example, homeowners may want to measure the change of formaldehyde levels in their house before and after installing new furniture. This sensor may also be deployed by occupants to reduce the cost of a large-scale exposure assessment study.

Ambient levels of atmospheric carbonyls in Beijing during the 2008 Olympic Games

The measurements of atmospheric carbonyls concentrations in Beijing were conducted from 12 July to 8 October, 2008, covering the periods of the 2008 Olympic Games and Paralympic Games. Six carbonyls, including formaldehyde, acetaldehyde, acetone, butyraldehyde, valeraldehyde, and hexaldehyde, were identified in all air samples. The total average concentrations of these carbonyls before, during, and after traffic restriction were (48.1 +/- 15.2), (36.6 +/- 14.5) and (23.4 +/- 12.3) microg/m3, respectively. Compared with the period after traffic restriction, the distinct high concentrations of the carbonyls before and during traffic restriction were primarily ascribed to the remarkable contribution of photochemical reactions. With respect to our previous investigation in the summer of 2005, the reductions of formaldehyde, acetaldehyde and acetone during traffic restriction period were about 64%, 47% and 27%, respectively, indicating that the air cleaning actions adopted by the Chinese government for the two games were efficient. The lowest levels of atmospheric carbonyls and the extremely high composition proportion of acetone after the traffic restriction were mainly attributed to the long-term effect of the control measures for the two games.

Acrolein environmental levels and potential for human exposure

This article provides environmental information on acrolein including environmental fate, potential for human exposure, analytical methods, and a listing of regulations and advisories. Acrolein may be released to the environment in emissions and effluents from its manufacturing and use facilities, in emissions from combustion processes (including cigarette smoking and combustion of petrochemical fuels), from direct application to water and waste water as a slimicide and aquatic herbicide, as a photooxidation product of various hydrocarbon pollutants found in air (including propylene and 1,3-butadiene), and from land disposal of some organic waste materials. Acrolein is a reactive compound and is unstable in the environment. The general population may be exposed to acrolein through inhalation of contaminated air and through ingestion of certain foods. Important sources of acrolein exposure are via inhalation of tobacco smoke and environmental tobacco smoke and via the overheating of fats contained in all living matter. There is potential for exposure to acrolein in many occupational settings as the result of its varied uses and its formation during the combustion and pyrolysis of materials such as wood, petrochemical fuels, and plastics.

Diurnal cycles of acrolein and other small aldehydes in regions impacted by vehicle emissions

This research determined the diurnal and seasonal differences in the ambient atmospheric concentrations of acrolein and several small aldehydes and attempted to link the chemicals to their potential sources. Two summertime and two wintertime sampling episodes were conducted in Roseville, CA at a site located near several busy roadways. One additional sampling episode was conducted at a remote site in the summer to estimate regional background concentrations of aldehydes. Each sampling episode consisted of duplicate samples collected every two hours around the clock for three days. Acrolein concentrations did not correlate with traffic density, ozone concentrations, or tracers of direct vehicle emissions, which argues against vehicles being a dominant source of ambient acrolein through primary emissions or secondary oxidation products. The results showed that wintertime acrolein concentrations correlated well with 2-furaldehyde, which is a tracer of biomass burning, thus suggesting that wood smoke is an important source of ambient acrolein. Other regularly detected carbonyls were tentatively assigned to different source classes (direct vehicle emissions, photochemical oxidation, wood smoke or transport from the Sierra Nevada Mountains) based on time series patterns and correlations with indicators of potential sources (e.g., ozone, traffic density, etc.).

The determination of ambient formaldehyde using a dual coil system and an assessment of dominant factors that influence its abundance in Korea

An enhanced dual coil 2,4-dinitrophenylhydrazine (DNPH) derivatization method (dual coil/DNPH) allowed the quantitative determination of formaldehyde (HCHO) in ambient air. In this method, traceable HCHO was collected using a coil sampler connected in series and lacking a long sampling tube. It was then analyzed using liquid chromatography followed by UV detection of the DNPH derivatives. The method is based on the reaction of formaldehyde with DNPH to produce 2,4-dinitrophenylhydrazone. The detection limits (3sigma) were 0.10-0.40 ppbv with a precision ranging from 0.84 to 4.09% RSD. The results of dual coil/DNPH and conventional DNPH cartridge methods were generally well correlated: HCHO (dual coil/DNPH)=0.97 (+/-0.13) vs. HCHO (DNPH Cartridge)+0.33 (+/-0.33), r=0.82. The dual coil/DNPH method was used to measure gaseous HCHO in the atmosphere of Metropolitan Seoul during the summer 2000 and 2001, and in Gwangju during the fall of 2001 and 2002. The daytime mean concentration of HCHO was 4.52 (+/-5.69) and 3.21 (+/-1.27) ppbv in Metropolitan Seoul for 10-12 August 2000 and 29-31 May 2001, respectively, and 1.73 (+/-0.98), 3.04 (+/-2.25), 2.70 (+/-1.70), and 2.01 (+/-2.28) ppbv in Gwangju City during 22-27 September 2001, 17-24 October 2001, 9-13 October 2002, and 28 October to 2 November 2002, respectively. The HCHO in Seoul from 10-12 August 2000 was mainly the result of photochemical processes, while direct emissions from vehicles and long-range transport of air from China contributed during 29-31 May 2001. During 22-27 September 2001, 17-24 October 2001, and 9-13 October 2002 in Gwangju, the HCHO came primarily from photochemical processes, although some air affected by biomass burning admixed in the late afternoon. The increase in the HCHO concentration on 20 October 2001 and from 28 October to 2 November 2002 was attributed mainly to direct emissions from biomass burning in farmland near the measurement site.

Fumigant action of acrolein on insects and seed viability

In laboratory experiments toxicity of acrolein vapors was investigated against 4 species of stored-product insects. In empty-space trials, estimated of the median lethal dosages of acrolein against adults of Oryzaephilus surinamensis (L.), Sitophilus oryzae (L.), Rhyzopertha dominica (F.) and Tribolium castaneum (Herbst), were 1.87, 2.35, 3.12 and 6.65 mg L(-1), respectively. Penetration tests revealed that acrolein vapors could penetrate into the wheat mass and kill concealed insects in interkernel spaces. Comparison of LC50 values between empty-space tests and penetration experiments after 24 h exposure indicated that the increase in penetration toxicity was 6.34, 6.31, 7.17 and 4.54-fold for O. surinamensis, S. oryzae, R. dominica and T. castaneum, respectively. In the hidden infestation trials, the acrolein vapors destroyed all the developmental stages of S. oryzae and R. dominica concealed inside the wheat kernels, resulted in a complete control with dosage of 80 mg L(-1) for 24 h and subsequently observed during 8 weeks after the exposure. Wheat germination rate was diminished by fumigation with acrolein. The plumule length was reduced following exposure to all dosages of acrolein. It is concluded that acrolein could be considered as a potential compound for empty-space fumigations.

Housing characteristics and indoor concentrations of nitrogen dioxide and formaldehyde in Quebec City, Canada

Concentrations of nitrogen dioxide and formaldehyde were determined in a study of 96 homes in Quebec City, Canada, between January and April 2005. In addition, relative humidity, temperature, and air change rates were measured in homes, and housing characteristics were documented through a questionnaire to occupants. Half of the homes had ventilation rates below 7.5 L/s person. Nitrogen dioxide (NO2) and formaldehyde concentrations ranged from 3.3 to 29.1 microg/m3 (geometric mean 8.3 microg/m3) and from 9.6 to 90.0 microg/m3 (geometric mean of 29.5 microg/m3), respectively. The housing characteristics documented in the study explained approximately half of the variance of NO2 and formaldehyde. NO2 concentrations in homes were positively correlated with air change rates (indicating a significant contribution of outdoor sources to indoor levels) and were significantly elevated in homes equipped with gas stoves and, to a lesser extent, in homes with gas heating systems. Formaldehyde concentrations were negatively correlated with air change rates and were significantly elevated in homes heated by electrical systems, in those with new wooden or melamine furniture purchased in the previous 12 months, and in those where painting or varnishing had been done in the sampled room in the previous 12 months. Results did not indicate any significant contribution of indoor combustion sources, including wood-burning appliances, to indoor levels of formaldehyde. These results suggest that formaldehyde concentrations in Quebec City homes are caused primarily by off-gassing, and that increasing air change rates in homes could reduce exposure to this compound. More generally, our findings confirm the influence of housing characteristics on indoor concentrations of NO2 and formaldehyde.

Aldehyde sources, metabolism, molecular toxicity mechanisms, and possible effects on human health

Aldehydes are organic compounds that are widespread in nature. They can be formed endogenously by lipid peroxidation (LPO), carbohydrate or metabolism ascorbate autoxidation, amine oxidases, cytochrome P-450s, or myeloperoxidase-catalyzed metabolic activation. This review compares the reactivity of many aldehydes towards biomolecules particularly macromolecules. Furthermore, it includes not only aldehydes of environmental or occupational concerns but also dietary aldehydes and aldehydes formed endogenously by intermediary metabolism. Drugs that are aldehydes or form reactive aldehyde metabolites that cause side-effect toxicity are also included. The effects of these aldehydes on biological function, their contribution to human diseases, and the role of nucleic acid and protein carbonylation/oxidation in mutagenicity and cytotoxicity mechanisms, respectively, as well as carbonyl signal transduction and gene expression, are reviewed. Aldehyde metabolic activation and detoxication by metabolizing enzymes are also reviewed, as well as the toxicological and anticancer therapeutic effects of metabolizing enzyme inhibitors. The human health risks from clinical and animal research studies are reviewed, including aldehydes as haptens in allergenic hypersensitivity diseases, respiratory allergies, and idiosyncratic drug toxicity; the potential carcinogenic risks of the carbonyl body burden; and the toxic effects of aldehydes in liver disease, embryo toxicity/teratogenicity, diabetes/hypertension, sclerosing peritonitis, cerebral ischemia/neurodegenerative diseases, and other aging-associated diseases.

Levels and determinants of formaldehyde, acetaldehyde, and acrolein in residential indoor air in Prince Edward Island, Canada

This study was undertaken to determine the concentrations of formaldehyde, acetaldehyde, and acrolein in air samples taken in some Canadian houses and to determine the association between aldehyde levels and housing characteristics. Concentrations of formaldehyde, acetaldehyde, and acrolein were measured in 59 homes in Prince Edward Island, Canada, during the winter of 2002. Housing characteristics were documented through inspection and by interviews of occupants. Formaldehyde, acetaldehyde, and acrolein concentrations ranged from 5.5 to 87.5 microg/m(3) (median, 29.6 microg/m(3)), from 4.4 to 79.1 microg/m(3) (median, 18.9 microg/m(3)), and from 0.1 to 4.9 microg/m(3) (median, 0.9 microg/m(3)), respectively. Formaldehyde levels were elevated in homes built after 1970. Acetaldehyde and acrolein levels were elevated in homes inhabited by at least one smoker and in homes built 1970--1985 and were correlated with absolute humidity and carbon dioxide, two variables likely to be surrogates for lower air exchange rates. In conclusion, lower air exchange rates appear to be important determinants of formaldehyde, acetaldehyde, and acrolein levels in homes. These data also confirm that smoking is a significant source of acetaldehyde and acrolein and indoor air.

Summertime ambient formaldehyde in five U.S. metropolitan areas: Nashville, Atlanta, Houston, Philadelphia, and Tampa

First, we briefly review the atmospheric chemistry and previous intercomparison measurements for HCHO, with special reference to the diffusion scrubber Hantzsch reaction based fluorescence instrument used in the field studies reported herein. Then we discuss summertime HCHO levels in five major U.S. cities measured over 1999-2002, primarily from ground-based measurements. Land-sea breeze circulations play a major role in observed concentrations in coastal cities. Very high HCHO peak mixing ratios were observed in Houston (>47 ppb) where the overall median mixing ratio was 3.3 ppb; the corresponding values in Atlanta were approximately >18 and 7.9 ppb, respectively. The peak and median mixing ratios (9.3 and 2.3 ppb) were the lowest for Tampa, where the land-sea breeze also played an important role. In several cities, replicate HCHO measurements were made by direct spectroscopic instruments; the instruments were located kilometers from each other and addressed very different heights (e.g., 106 vs 10 m). Even under these conditions, there was remarkable qualitative and often quantitative agreement between the different instruments, when they were all sampling the same air mass within a short period of each other. Local chemistry dominates how HCHO is formed and dissipated. The high concentrations in Houston resulted from emissions near the ship channel; the same formaldehyde plume was measured at two sites and clearly ranged over tens of kilometers. Local micrometeorology is another factor. HCHO patterns measured at a high-rise site in downtown Nashville were very much in synchrony with other ground sites 12 km away until July 4 celebrations whence HCHO concentrations at the downtown site remained elevated for several days and nights. The formation and dissipation of HCHO in the different cities are discussed in terms of other concurrently measured species and meteorological vectors. The vertical profiles of HCHO in and around Tampa under several different atmospheric conditions are presented. The extensive data set represented in this paper underscores that urban HCHO measurements can now be made easily; the agreement between disparate instruments (that are independently calibrated or rely on the absolute absorption cross section) further indicates that such measurements can be done reliably and accurately for this very important atmospheric species. The data set presented here can be used as a benchmark for future measurements if the use of formaldehyde precursors such as methanol or methyl tert-butyl ether (MTBE) as oxygenated fuel additives increases in the future.

DNA damage in lymphocytes of rural Indian women exposed to biomass fuel smoke as assessed by the Comet assay

The Comet assay has found wide acceptance in monitoring human genotoxicity caused by lifestyle and occupational and environmental factors. In the present study, we have used the Comet assay to measure the DNA damage in a population of rural Indian women cooking with biomass fuels (BMFs; fire wood and cow dung cakes). Out of 144 volunteers, 70 used BMFs for domestic cooking, while the remaining 74 used liquefied petroleum gas (LPG) and served as a reference population. All the individuals had comparable socioeconomic backgrounds and were between 20 and 55 years of age. Significantly higher levels of DNA damage were observed for BMF users than for LPG users. For BMF users in comparison with the reference population, Olive tail moment was 3.83 +/- 0.15 (arbitrary units) vs. 2.77 +/- 0.07 (P < 0.001); % tail DNA was 11.19 +/- 0.35 vs. 8.29 +/- 0.20 (P < 0.001); and comet tail length (microm) was 51.15 +/- 1.37 vs. 40.26 +/- 0.88 (P < 0.001). Similar significant differences were found when the groups were stratified by age and length of exposure. This study suggests that exposure to BMF smoke leads to greater levels of DNA damage than exposure to LPG combustion products.

The toxicology of inhaled woodsmoke

In addition to developing nations relying almost exclusively upon biomass fuels, such as wood for cooking and home heating, North Americans, particularly in Canada and the northwestern and northeastern sections of the United States, have increasingly turned to woodburning as an alternate method for domestic heating because of increasing energy costs. As a result, the number of households using woodburning devices has increased dramatically. This has resulted in an increase in public exposure to indoor and outdoor woodsmoke-associated pollutants, which has prompted widespread concern about the adverse human health consequences that may be associated with prolonged woodsmoke exposure. This mini-review article brings together many of the human and animal studies performed over the last three decades in an attempt to better define the toxicological impact of inhaled woodsmoke on exposed children and adults; particular attention is given to effects upon the immune system. General information regarding occurrence and woodsmoke chemistry is provided so as to set the stage for a better understanding of the toxicological impact. It can be concluded from this review that exposure to woodsmoke, particularly for children, represents a potential health hazard. However, despite its widespread occurrence and apparent human health risks, relatively few studies have focused upon this particular area of research. More laboratory studies aimed at understanding the effects and underlying mechanisms of woodsmoke exposure, particularly on those individuals deemed to be at greatest risk, are badly needed, so that precise human health risks can be defined, appropriate regulatory standards can be set, and accurate decisions can be made concerning the use of current and new woodburning devices.

Epithelium-linked smooth muscle hyperresponsiveness in ferret tracheae exposed to acrolein

The effects of acrolein exposure on tissue uptake and airway responses to substance P (SP) and nitroprusside (NIP) were determined in excised ferret tracheae exposed for 60 min to a constant flow of air or 0.3 and 3.5 ppm acrolein-air mixtures. Histological examination indicated that whereas the epithelium of an air-exposed trachea was intact with no apparent injury, acrolein-induced epithelium damage was more pronounced at 3.5 than at 0.3 ppm vapor concentration. The fractional uptake of acrolein into the tracheal tissue continually decreased during the 1 h of exposure and was found to be significantly concentration dependent at the 60 min measurement point. This suggests that the uptake process of acrolein in the mucosal layer is not linear and is dominated by irreversible reaction. In the absence of the neutral endopeptidase inhibitor, phosphoramidon, acrolein significantly increased the maximal response to SP. Pretreatment with phosphoramidon abolished the differential effect of acrolein on airway smooth muscle response to SP. Nitroprusside relaxed acrolein-exposed tracheal rings precontracted with carbachol to their baseline tone, but it induced relaxation of air-exposed tracheal rings below their initial resting tension, indicating the presence of endogenous as well as induced tone. Pretreatment with NIP also abolished the differential effect of acrolein on airway response to carbachol and modified the potency of this agonist. We conclude that acrolein-induced hyperresponsiveness of the underlying airway smooth muscle is linked to inactivation of neutral endopeptidase synthesis as well as to loss of epithelium-derived relaxation factor.

Fate and effects of acrolein

Acrolein is a highly toxic, reactive, and irritating aldehyde that occurs as a product of organic pyrolysis, as a metabolite of a number of compounds, and as a residue in water when used for the control of aquatic organisms. It is an intermediate in the production of acrylic acid, DL-methionine, and numerous other agents. Its major direct use is as a biocide for the control of aquatic flora and fauna. It is introduced to the environment from a variety of sources, including organic combustion such as automobile exhaust, cigarette smoke, and manufacturing and cooking emissions, as well as direct biocidal applications. Organic combustion from both fixed and mobile sources is the significant source of acrolein in the atmosphere; it represents up to 8% of the total aldehydes generated from vehicles and residential fireplaces and 13% of total atmospheric aldehydes. This reactive aldehyde also occurs in organisms as a metabolite of allyl alcohol, allylamine, spermine, spermidine, and the anticancer drug cyclophosphamide, and as a product of UV radiation of the skin lipid triolein. Furthermore, small amounts are found in foods; when animal or vegetable fats are overheated, however, large amounts are produced. Most human contact occurs during exposure to smoke from cigarettes, automobiles, industrial processes, and structural and vegetation fires. Besides cigarette smoke, occupational exposures are a common mode of human contact, particularly in industries that involve combustion of organic compounds. Firefighters, in particular, are exposed to extremely high levels during the extinguishment and overhaul phases of their work. Water may contain significant levels of the herbicide. It has been found in paper mill and municipal effluents at 20-200 micrograms/L, and at 30 micrograms/L as far as 64 km downstream from the point of application. The USEPA-recommended water quality criteria for freshwater are only 1.2 micrograms/L (24-hr avg) and 2.7 micrograms/L (maximum ceiling). Acrolein is highly reactive, and intercompartmental transport is limited. However, it is eliminated from aqueous environments by volatilization and hydration to beta-hydroxypropanal, after which biotransformation occurs, with a half-life of 7-10 d. The Koc for acrolein is 24, and it is not likely to be retained in soil; activated carbon adsorbs only 30% from solution. Thus, the aldehyde is either leached extensively in moist soil or volatilizes quickly from dry soil. It is eliminated from air by reaction with .OH (half-life, 0.5-1.2 d), NOx (half-life, 16 d), and O3 (half-life, 59 d), as well as by photolysis and wet deposition. As expected from its high water solubility, bioaccumulation is low. Acrolein is highly toxic by all routes of exposure. The respiratory system is the most common target: exposure causes localized irritation, respiratory distress, pulmonary edema, cellular necrosis, and increased susceptibility to microbial diseases. Additionally, acute inhalation studies verify that it is a severe respiratory irritant that affects respiratory rates. Respiratory rate depression may have a protective effect by minimizing vapor inhalation, thereby explaining the subadditive effect of acrolein when combined with the other toxic combustion by-products CO and HCHO. Liquid contact with the skin and eyes causes severe irritation, opaque or cloudy corneas, and localized epidermal necrosis, but no allergic contact dermatitis. The cardiovascular system is affected, resulting in increased blood pressure, platelet aggregation, and quick cessation of beating in perfused rat hearts. It may also inhibit mitochondrial oxidative phosphorylation in the myocardium. Acute LD50s and LC50s are low. Levels are 7-46 mg/kg and 18-750 mg/m3, respectively, in rats; aquatic organisms are affected above 11.4 micrograms/L.(ABSTRACT TRUNCATED)