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

Acrolein Induces Changes in Cell Membrane and Cytosol Proteins of Erythrocytes

High concentrations of acrolein (2-propenal) are found in polluted air and cigarette smoke, and may also be generated endogenously. Acrolein is also associated with the induction and progression of many diseases. The high reactivity of acrolein towards the thiol and amino groups of amino acids may cause damage to cell proteins. Acrolein may be responsible for the induction of oxidative stress in cells. We hypothesized that acrolein may contribute to the protein damage in erythrocytes, leading to the disruption of the structure of cell membranes. The lipid membrane fluidity, membrane cytoskeleton, and osmotic fragility were measured for erythrocytes incubated with acrolein for 24 h. The levels of thiol, amino, and carbonyl groups were determined in cell membrane and cytosol proteins. The level of non-enzymatic antioxidant potential (NEAC) and TBARS was also measured. The obtained research results showed that the exposure of erythrocytes to acrolein causes changes in the cell membrane and cytosol proteins. Acrolein stiffens the cell membrane of erythrocytes and increases their osmotic sensitivity. Moreover, it has been shown that erythrocytes treated with acrolein significantly reduce the non-enzymatic antioxidant potential of the cytosol compared to the control.

Wildfires Increase Concentrations of Hazardous Air Pollutants in Downwind Communities

Due in part to climate change, wildfire activity is increasing, with the potential for greater public health impact from smoke in downwind communities. Studies examining the health effects of wildfire smoke have focused primarily on fine particulate matter (PM2.5), but there is a need to better characterize other constituents, such as hazardous air pollutants (HAPs). HAPs are chemicals known or suspected to cause cancer or other serious health effects that are regulated by the United States (US) Environmental Protection Agency. Here, we analyzed concentrations of 21 HAPs in wildfire smoke from 2006 to 2020 at 309 monitors across the western US. Additionally, we examined HAP concentrations measured in a major population center (San Jose, CA) affected by multiple fires from 2017 to 2020. We found that concentrations of select HAPs, namely acetaldehyde, acrolein, chloroform, formaldehyde, manganese, and tetrachloroethylene, were all significantly elevated on smoke-impacted versus nonsmoke days (P < 0.05). The largest median increase on smoke-impacted days was observed for formaldehyde, 1.3 μg/m3 (43%) higher than that on nonsmoke days. Acetaldehyde increased 0.73 μg/m3 (36%), and acrolein increased 0.14 μg/m3 (34%). By better characterizing these chemicals in wildfire smoke, we anticipate that this research will aid efforts to reduce exposures in downwind communities.

Acrolein Exposure Impaired Glucose Homeostasis and Increased Risk of Type 2 Diabetes: An Urban Adult Population-Based Cohort Study with Repeated Measures

Acrolein is an identified high-priority hazardous air pollutant ubiquitous in daily life and associated with cardiometabolic risk that attracts worldwide attention. However, the etiology role of acrolein exposure in glucose dyshomeostasis and type 2 diabetes (T2D) is unclear. This repeated-measurement prospective cohort study included 3522 urban adults. Urine/blood samples were repeatedly collected for determinations of acrolein metabolites (N-acetyl-S-(3-hydroxypropyl)-l-cysteine, N-acetyl-S-(2-carboxyethyl)-l-cysteine; acrolein exposure biomarkers), glucose homeostasis, and T2D at baseline and a three-year follow-up. We found that each 3-fold increment in acrolein metabolites was cross-sectionally associated with 5.91-6.52% decrement in homeostasis model assessment-insulin sensitivity (HOMA-IS) and 0.07-0.14 mmol/L, 4.02-4.57, 5.91-6.52, 19-20, 18-19, and 23-31% increments in fasting glucose (FPG), fasting insulin (FPI), HOMA-insulin resistance (HOMA-IR), risks of prevalent IR, impaired fasting glucose (IFG), and T2D, respectively; longitudinally, participants with sustained-high acrolein metabolite levels had increased risks of incident IR, IFG, and T2D by 63-80, 87-99, and 120-154%, respectively (P < 0.05). In addition, biomarkers of heme oxygenase-1 activity (exhaled carbon monoxide), lipid peroxidation (8-iso-prostaglandin-F2α), protein carbonylation (protein carbonyls), and oxidative DNA damage (8-hydroxy-deoxyguanosine) mediated 5.00-38.96% of these associations. Our study revealed that acrolein exposure may impair glucose homeostasis and increase T2D risk via mediating mechanisms of heme oxygenase-1 activation, lipid peroxidation, protein carbonylation, and oxidative DNA damage.

Cross-sectional and longitudinal associations of acrolein exposure with pulmonary function alteration: Assessing the potential roles of oxidative DNA damage, inflammation, and pulmonary epithelium injury in a general adult population

BACKGROUND

Acrolein is a significant high priority hazardous air pollutant with pulmonary toxicity and the leading cause of most noncancer adverse respiratory effects among air toxics that draws great attention. Whether and how acrolein exposure impacts pulmonary function remain inconclusive.

OBJECTIVES

To assess the association of acrolein exposure with pulmonary function and the underlying roles of oxidative DNA damage, inflammation, and pulmonary epithelium integrity.

METHODS

Among 3,279 Chinese adults from the Wuhan-Zhuhai cohort, associations of urinary acrolein metabolites (N-Acetyl-S-(2-carboxyethyl)-L-cysteine, CEMA; N-Acetyl-S-(3-hydroxypropyl)-L-cysteine, 3HPMA) as credible biomarkers of acrolein exposure with pulmonary function were analyzed by linear mixed models. Joint effects of biomarkers of oxidative DNA damage (8-hydroxy-deoxyguanosine), inflammation (C-reactive protein, CRP), and pulmonary epithelium integrity (Club cell secretory protein, CC16) with acrolein metabolites on pulmonary function and the mediating roles of these biomarkers were assessed. Besides, a subgroup (N = 138) was randomly recruited from the cohort to assess the stabilities of acrolein metabolites and their longitudinal associations with pulmonary function change in three years.

RESULTS

Significant inverse dose-response relationships between acrolein metabolites and pulmonary function were found. Each 10-fold increment in CEMA, 3HPMA, or ΣUACLM (CEMA + 3HPMA) was cross-sectionally related to a 68.56-, 40.98-, or 46.02-ml reduction in FVC and a 61.54-, 43.10-, or 50.14-ml reduction in FEV₁, respectively (P < 0.05). Furthermore, acrolein metabolites with fair to excellent stabilities were found to be longitudinally associated with pulmonary function decline in three years. Joint effects of acrolein metabolites with 8-hydroxy-deoxyguanosine, CRP, and CC16 on pulmonary function were identified. CRP significantly mediated 5.97% and 5.51% of CEMA-associated FVC and FEV₁ reductions, respectively. 8-hydroxy-deoxyguanosine significantly mediated 6.78%, 6.88%, and 7.61% of CEMA-, 3HPMA-, and ΣUACLM-associated FVC reductions, respectively.

CONCLUSIONS

Acrolein exposure of general adults was cross-sectionally and longitudinally related to pulmonary function decline, which was aggravated and/or partly mediated by oxidative DNA damage, inflammation, and pulmonary epithelium injury.

Determination of acrolein in ambient air and in the atmosphere of environmental test chambers

Acrolein (2-propenal) is a reactive substance undergoing multiple reaction pathways and an airborne pollutant with known corrosive, toxic and hazardous effects to the environment and to human health. So far, investigating the occurrence of acrolein in indoor air has been challenging due to analytical limitations. The classic DNPH-method has proven to be error-prone, even though it is still recommended in specific testing protocols. Thus, different approaches for an accurate determination of ambient acrolein have been introduced. In this work, an overview of already published data regarding emission sources and air concentrations is provided. In addition, a new method for the quantitative determination of acrolein in environmental test chambers and in indoor air is presented. Analysis is carried out using thermal desorption and coupled gas chromatography/mass spectrometry (TD-GC/MS) after sampling on the graphitized carbon black (GCB) Carbograph™ 5TD. All analytical steps have been carefully validated and compared with derivatization techniques (DNPH and DNSH) as well as online detection using PTR-QMS. The sampling time is short due to the low air collection volume of 4 L. Although derivatization is not applied, a detection limit of 0.1 μg m^-3 can be achieved. By increasing the sampling volume to 6 L, the limit of detection can be lowered to 0.08 μg m^-3. No breakthrough during sampling or analyte loss during storage of the acrolein laden sampling tubes was found. Therefore, the presented method is robust, easy-to-handle and also very suitable for routine analyses and surveys.

Assessing the role of mineral particles in the atmospheric photooxidation of typical carbonyl compound

Mineral particles are ubiquitous in the atmosphere and exhibit an important effect on the photooxidation of volatile organic compounds (VOCs). However, the role of mineral particles in the photochemical oxidation mechanism of VOCs remains unclear. Hence, the photooxidation reactions of acrolein (ARL) with OH radical (OH) in the presence and absence of SiO₂ were investigated by theoretical approach. The gas-phase reaction without SiO₂ has two distinct pathways (H-abstraction and OH-addition pathways), and carbonyl-H-abstraction is the dominant pathway. In the presence of SiO₂, the reaction mechanism is changed, i.e., the dominant pathway from carbonyl-H-abstraction to OH-addition to carbonyl C-atom. The energy barrier of OH-addition to carbonyl C-atom deceases 21.33 kcal/mol when SiO₂ is added. Carbonyl H-atom of ARL is occupied by SiO₂ via hydrogen bond, and carbonyl C-atom is activated by SiO₂. Hence, the main product changes from H-abstraction product to OH-adduct in the presence of SiO₂. The OH-adduct exhibits a thermodynamic feasibility to yield HO₂ radical and carboxylic acid via the subsequent reactions with O₂, with implications for O₃ formation and surface acidity of mineral particles.

An overview of selected emerging outdoor airborne pollutants and air quality issues: The need to reduce uncertainty about environmental and human impacts

According to the literature, it is estimated that outdoor air pollution is responsible for the premature death in a range from 3.7 to 8.9 million persons on an annual basis across the world. Although there is uncertainty on this figure, outdoor air pollution represents one of the greatest global risks to human health. In North America, the rapid evolution of technologies (e.g., nanotechnology, unconventional oil and gas rapid development, higher demand for fertilizers in agriculture) and growing demand for ground, marine and air transportation may result in significant increases of emissions of pollutants that have not been carefully studied so far. As a result, these atmospheric pollutants insufficiently addressed by science in Canada and elsewhere are becoming a growing issue with likely human and environmental impacts in the near future. Here, an emerging pollutant is defined as one that meets the following criteria: 1) potential or demonstrated risk for humans or the environment, 2) absence of Canada-wide national standard, 3) insufficient routine monitoring, 4) yearly emissions greater than one ton in Canada, 5) insufficient data concerning significant sources, fate, and detection limit, and 6) insufficiently addressed by epidemiological studies. A new methodology to rank emerging pollutants is proposed here based on weighting multiple criteria. Some selected emerging issues are also discussed here and include the growing concern of ultrafine or nanoparticles, growing ammonia emissions (due to rapid expansion of the agriculture), increased methane/ethane/propane emissions (due to the expanding hydraulic fracturing in the oil and gas sector) and the growing transportation sector. Finally, the interaction between biological and anthropogenic pollution has been found to be a double threat for public health. Here, a multidisciplinary and critical overview of selected emerging pollutants and related critical issues is presented with a focus in Canada.Implications: This overview paper provides a selection methodology for emerging pollutants in the atmospheric environment. It also provides a critical discussion of some related issues. The ultimate objective is to inform about the need to 1) address emerging issues through adequate surface monitoring and modeling in order to inform the development of regulations, 2) reduce uncertainties by geographically mapping emerging pollutants (e.g., through data fusion, data assimilation of observations into air quality models) which can improve the scientific support of epidemiological studies and policies. This review also highlights some of the difficulties with the management of these emerging pollutants, and the need for an integrated approach.

Analysis of Carbonyl Compounds in Ambient Air by a Microreactor Approach

Aldehydes including formaldehyde, acetaldehyde, and acrolein are toxic organic components of air pollution that cause lung cancer and cardiovascular disease with chronic exposure. The commonly used method for determining the levels of carbonyl compounds based on the derivatizing agent 2,4-dinitrophenylhydrazine is of limited use for ketones and unsaturated aldehydes because of issues such as low capture efficiencies, unstable derivatives, and long sample collection times. This work details the analysis of carbonyls in ambient air by a microreactor approach. The microreactor is fabricated on a silicon wafer and has thousands of micropillars in a microfluidic channel for uniformly distributing the air flow through the channel. The surfaces of the micropillars are coated with a quaternary ammonium aminooxy reagent, 2-(aminooxy)ethyl-N,N,N-trimethylammonium iodide (ATM), for chemoselective capture of carbonyl compounds by means of oximation reactions. ATM-carbonyl adducts are eluted from the microreactor and directly analyzed by Fourier transform ion cyclotron resonance mass spectrometry and ultrahigh-performance liquid chromatography-mass spectrometry. More than 20 carbonyls were detected in ambient air samples. Acetone, 2-butanone, acetaldehyde, and formaldehyde were the most abundant carbonyls in ambient air of the studied urban areas.

Analysis of Carbonyl Compounds in Ambient Air by a Microreactor Approach

Aldehydes including formaldehyde, acetaldehyde, and acrolein are toxic organic components of air pollution that cause lung cancer and cardiovascular disease with chronic exposure. The commonly used method for determining the levels of carbonyl compounds based on the derivatizing agent 2,4-dinitrophenylhydrazine is of limited use for ketones and unsaturated aldehydes because of issues such as low capture efficiencies, unstable derivatives, and long sample collection times. This work details the analysis of carbonyls in ambient air by a microreactor approach. The microreactor is fabricated on a silicon wafer and has thousands of micropillars in a microfluidic channel for uniformly distributing the air flow through the channel. The surfaces of the micropillars are coated with a quaternary ammonium aminooxy reagent, 2-(aminooxy)ethyl-N,N,N-trimethylammonium iodide (ATM), for chemoselective capture of carbonyl compounds by means of oximation reactions. ATM-carbonyl adducts are eluted from the microreactor and directly analyzed by Fourier transform ion cyclotron resonance mass spectrometry and ultrahigh-performance liquid chromatography-mass spectrometry. More than 20 carbonyls were detected in ambient air samples. Acetone, 2-butanone, acetaldehyde, and formaldehyde were the most abundant carbonyls in ambient air of the studied urban areas.

Effects of maternal acrolein exposure during pregnancy on testicular testosterone production in fetal rats

Acrolein has been reported to have diverse toxic effects on various organs, including the reproductive system. However, little is known regarding the effects of maternal acrolein exposure on testicular steroidogenesis in male offspring. The present study investigated the effects of acrolein on fetal testosterone production and associated genes. Pregnant Sprague-Dawley rats were intraperitoneally injected with vehicle (normal saline) or 1, 2 or 5 mg/kg acrolein from gestational day (GD) 14–20, and fetal testes were examined on GD 21. Fetal body and testicular weights were markedly reduced in pups following exposure to high doses of acrolein (5 mg/kg) in late pregnancy. Notably, in utero exposure of 5 mg/kg acrolein significantly decreased the testicular testosterone level and downregulated the expression levels of steroidogenic acute regulatory protein (StAR) and 3β-hydroxysteroid dehydrogenase (3β-HSD), whereas the levels of other steroidogenic enzymes, including scavenger receptor class B, cholesterol side-chain cleavage enzyme and steroid 17 alpha-hydroxylase/17,20 lyase, were unaffected. Furthermore, the 3β-HSD immunoreactive area in the interstitial region of the fetal testes was reduced at a 5 mg/kg dose, whereas the protein expression levels of 4-hydroxynonenalwere dose-dependently increased following maternal exposure to acrolein. mRNA expression levels of insulin-like factor 3, a critical gene involved in testicular descent, were unaltered following maternal acrolein exposure. Taken together, the results of the present study suggested that maternal exposure to high doses of acrolein inhibited fetal testosterone synthesis, and abnormal expression of StAR and 3β-HSD may be associated with impairment of the steroidogenic capacity.

Cooking-related PM2.5 and acrolein measured in grocery stores and comparison with other retail types

We measured particulate matter (PM), acrolein, and other indoor air contaminants in eight visits to grocery stores in California. Retail stores of other types (hardware, furniture, and apparel) were also sampled on additional visits. Based on tracer gas decay data, most stores had adequate ventilation according to minimum ventilation rate standards. Grocery stores had significantly higher concentrations of acrolein, fine and ultrafine PM, compared to other retail stores, likely attributable to cooking. Indoor concentrations of PM2.5 and acrolein exceeded health guidelines in all tested grocery stores. Acrolein emission rates to indoors in grocery stores had a mean estimate about 30 times higher than in other retail store types. About 80% of the indoor PM2.5 measured in grocery stores was emitted indoors, compared to only 20% for the other retail store types. Calculations suggest a substantial increase in outdoor air ventilation rate by a factor of three from current level is needed to reduce indoor acrolein concentrations. Alternatively, acrolein emission to indoors needs to be reduced 70% by better capturing of cooking exhaust. To maintain indoor PM2.5 below the California annual ambient standard of 12 μg/m(3) , grocery stores need to use air filters with an efficiency rating higher than the MERV 8 air filters commonly used today.

Air toxics in Canada measured by the National Air Pollution Surveillance (NAPS) program and their relation to ambient air quality guidelines

This study reports ambient concentrations of 63 air toxics that were measured in Canada by the National Air Pollution Surveillance (NAPS) program over the period 2009-2013. Measured concentrations are compared with ambient air quality guidelines from Canadian jurisdictions, and compounds that exceeded guidelines are identified and discussed. Although this study does not assess risk or cumulative effects, air toxics that approached guidelines are also identified so that their potential contribution to ambient air toxics pollution can be considered. Eleven air toxics exceeded at least one guideline, and an additional 16 approached guidelines during the study period. Four compounds were measured using methods whose detection limits exceeded a guideline value, three of which could not be compared with guidelines, since they were not detected in any samples. The assessment of several metal(loid) concentrations is tentative, since they were measured only in fine particulate matter (PM) but compared with guidelines based on coarse or total PM. Improvements to sampling and analysis techniques for the latter compounds as well as for those whose methods are subject to known uncertainties would improve confidence in reported concentrations and their relation to applicable guidelines. Analysis of sampling strategies for all compounds found to exceed or approach guidelines would contribute to ensuring that their spatiotemporal coverage is adequate. Examination of the air toxics not measured by NAPS but having guidelines in Canadian jurisdictions or being included in other programs such as the U.S. National-Scale Air Toxics Assessment (NATA) would contribute to ensuring that the full suite of pollutants relevant to ambient air quality in Canada is subject to adequate study. The results of this study can be applied to evaluating the effectiveness of toxic substances management in Canada.

IMPLICATIONS

Recent measurements of 63 air toxics in Canada by the National Air Pollution Surveillance (NAPS) program showed that 11 compounds exceeded daily or annual ambient air quality guidelines and that an additional 16 compounds approached such guidelines within an order of magnitude. The results of this study can be applied to evaluating the effectiveness of toxic substances management in Canada and to identifying compounds that merit further investigation.

Molecular mechanisms of acrolein toxicity: relevance to human disease

Acrolein, a highly reactive unsaturated aldehyde, is a ubiquitous environmental pollutant and its potential as a serious environmental health threat is beginning to be recognized. Humans are exposed to acrolein per oral (food and water), respiratory (cigarette smoke, automobile exhaust, and biocide use) and dermal routes, in addition to endogenous generation (metabolism and lipid peroxidation). Acrolein has been suggested to play a role in several disease states including spinal cord injury, multiple sclerosis, Alzheimer's disease, cardiovascular disease, diabetes mellitus, and neuro-, hepato-, and nephro-toxicity. On the cellular level, acrolein exposure has diverse toxic effects, including DNA and protein adduction, oxidative stress, mitochondrial disruption, membrane damage, endoplasmic reticulum stress, and immune dysfunction. This review addresses our current understanding of each pathogenic mechanism of acrolein toxicity, with emphasis on the known and anticipated contribution to clinical disease, and potential therapies.

Thermal Decomposition of 2(3H) and 2(5H) Furanones: Theoretical Aspects

The thermal decomposition reactions of 2(3H) and 2(5H) furanones and their methyl derivatives are explored. Theoretical calculations of the barriers, reaction enthalpies, and the properties of these and intermediate species are reported using the composite model chemistry CBS-QB3 and also the functional M06-2X allied to the 6-311++G(d,p) basis set. Thus, the bond dissociation enthalpies, ionization energies, and unimolecular chemical kinetic rate constants in the high-pressure limit were computed. We show that flow reactor experiments that intimated that heating the 2(3H) furanone converts it to the isomeric 2(5H) furanone occurs via a 1 → 2 H-transfer reaction to an open ring ketenoic aldehyde. The latter can then ring close to the other isomeric structure. The final products acrolein and carbon monoxide are only formed from 2(3H), and acrolein will further decompose to ethylene and CO. Comparable channels explain the interconversion of 5-methyl-2(3H) furanone to its 2(5H) isomer and to the formation of methyl vinyl ketone and CO. The influence of the methyl group at other positions on the ring is hardly of significance except in the case of 5-methyl-2(5H) furanone where a hydrogen atom transfer from the methyl group leads to the formation of a doubly unsaturated carboxylic compound, 2,4-pentadienoic acid. Studies of the UV photolysis of the parent compounds in both low-temperature inert argon matrices and in solution are broadly in accord with the thermal findings insofar as product formation is concerned and with our theoretical calculations. The dominant features of the early decomposition chemistry of these compounds are simple hydrogen transfer and simultaneous ring opening reactions, which do however result in some quite unusual species.

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.