Chemical reactivities of ambient air samples in three Southern California communities

Combined adjuvant effects of ambient vapor-phase organic components and particulate matter potently promote allergic sensitization and Th2-skewing cytokine and chemokine milieux in mice: The importance of mechanistic multi-pollutant research

Although exposure to ambient particulate matter (PM) is linked to asthma, the health effects of co-existing vapor-phase organic pollutants (vapor) and their combined effects with PM on this disease are poorly understood. We used a murine asthma model to test the hypothesis that exposure to vapor would enhance allergic sensitization and this effect would be further strengthened by co-existing PM. We found that vapor and PM each individually exerted adjuvant effects on OVA sensitization. Co-exposure to vapor and PM during sensitization further enhanced allergic lung inflammation and OVA-specific antibody production which was accompanied by pulmonary cytokine/chemokine milieu that favored T-helper 2 immunity (i.e. increased IL-4, downregulation of Il12a and Ifng, and upregulation of Ccl11 and Ccl8). TNFα, IL-6, Ccl12, Cxcl1 and detoxification/antioxidant enzyme responses in the lung were pollutant-dependent. Inhibition of lipopolysaccharide-induced IL-12 secretion from primary antigen-presenting dendritic cells correlated positively with vapor's oxidant potential. In conclusion, concurrent exposure to vapor and PM led to significantly exaggerated adjuvant effects on allergic lung inflammation which were more potent than that of each pollutant type alone. These findings suggest that the effects of multi-component air pollution on asthma may be significantly underestimated if research only focuses on a single air pollutant (e.g., PM).

Oxidative potential of aerosolized metalworking fluids in occupational settings

The oxidative potential (OP) measures the ability of pollutants to oxidize a chemical/biological probe. Such assays are starting to gain acceptance as integrative exposure metrics associated with inflammatory-based pathologies. Diseases such as asthma, rhinitis or cancers are reported for workers exposed to oil mist, which are aerosols of metal working fluids (MWF) emitted during the machining of metals. Measuring oil mist in the air is challenging, and exposures are often quantified as the mass fraction, which does not account for exposures to the gaseous fraction. Consequently, exposures are underestimated and furthermore, the hazardous property of oil mist is not assessed. We postulate that it is more relevant to assess occupational exposures to the hazardous fractions of oil mist by measuring OP than by simply measuring mass. We characterized exposures to straight and water-based MWF among workers in the French and Swiss mechanical industry using standard methods for oil mist and the ferrous orange xylenol assay for OP assessment (OP^FOX). Considering the particulate fraction, the water-based MWF presented the greatest OP^FOX. The OP was associated with organic carbon and iron content. The gaseous fraction of the oil mist presented also an important redox activity, particularly in workshops where straight oils were used. The hexanal concentration was associated with this OP^FOX. The OP^FOX measurement is thus integrative of multiple parameters, and bring complementary information when assessing MWF exposures. Our results highlight that OP^FOX account for MWF type and could be an interesting parameter to characterize such exposure.

Chemical and Biological Characterization of Particulate Matter (PM 2.5) and Volatile Organic Compounds Collected at Different Sites in the Los Angeles Basin

Background: Most studies on air pollution (AP) exposure have focused on adverse health effects of particulate matter (PM). Less well-studied are the actions of volatile organic compounds (VOCs) not retained in PM collections. These studies quantified chemical and biological properties of both PM2.5 and VOCs. Methods: Samples were collected near the Port of Los Angeles (Long Beach, LB), railroads (Commerce, CM), and a pollution-trapping topography-site (San Bernardino, SB). Quantitative assays were conducted: (1) chemical—prooxidant and electrophile content, (2) biological—tumor necrosis factor-α (TNF-α) and heme oxygenase-1 (HO-1) expression (3), VOC modulation of PM effects and (4), activation of the antioxidant response element (ARE) using murine RAW 264.7 macrophages. Results: SB site samples were the most potent in the chemical and biological assays, followed by a CM railroad site. Only PM2.5 exhibited significant proinflammatory responses. VOCs were more potent than PM2.5 in generating anti-inflammatory responses; further, VOC pretreatment reduced PM-associated TNF-α expression. VOCs significantly increased ARE activation compared to their corresponding PM2.5 which remained at background levels. Conclusion: Ambient VOCs are major contributors to adaptive responses that can modulate PM effects, in vitro, and, as such, need to be included in comprehensive assessments of AP.

Kefir peptides alleviate particulate matter <4 μm (PM4.0)-induced pulmonary inflammation by inhibiting the NF-κB pathway using luciferase transgenic mice

Kefir peptides, generated by kefir grain fermentation of milk proteins, showed positive antioxidant effects, lowered blood pressure and modulated the immune response. In this study, kefir peptide was evaluated regarding their anti-inflammatory effects on particulate matter <4 μm (PM_4.0)-induced lung inflammation in NF-κB-luciferase^+/+ transgenic mice. The lungs of mice under 20 mg/kg or 10 mg/kg PM_4.0 treatments, both increased significantly the generation of reactive oxygen species (ROS) and inflammatory cytokines; increased the protein expression levels of p-NF-κB, NLRP3, caspase-1, IL-1β, TNF-α, IL-6, IL-4 and α-SMA. Thus, we choose the 10 mg/kg of PM_4.0 for animal trials; the mice were assigned to four treatment groups, including control group (saline treatment), PM_4.0 + Mock group (only PM_4.0 administration), PM_4.0 + KL group (PM_4.0 + 150 mg/kg low-dose kefir peptide) and PM_4.0 + KH group (PM_4.0 + 500 mg/kg high-dose kefir peptide). Data showed that treatment with both doses of kefir peptides decreased the PM_4.0-induced inflammatory cell infiltration and the expression of the inflammatory mediators IL-lβ, IL-4 and TNF-α in lung tissue by inactivating NF-κB signaling. The oral administrations of kefir peptides decrease the PM_4.0-induced lung inflammation process through the inhibition of NF-κB pathway in transgenic luciferase mice, proposing a new clinical application to particulate matter air pollution-induced pulmonary inflammation.

Chemical speciation, including polycyclic aromatic hydrocarbons (PAHs), and toxicity of particles emitted from meat cooking operations

We assessed the chemical properties and oxidative stress of particulate matter (PM) emissions from underfired charbroiled meat operations with and without the use of aftertreatment control technologies. Cooking emissions concentrations showed a strong dependence on the control technology utilized, with all emission rates showing decreases with the control technologies compared to the baseline testing. The organic acids profile was dominated by the saturated nonanoic, myristic, palmitic, and stearic acids, and the unsaturated oleic, elaidic, and palmitoleic acids. Cholesterol was also found in relatively high concentrations. Lower and medium-weight polycyclic aromatic hydrocarbons (PAHs) were the dominant species for all cooking experiments. Heavier PAHs were also detected in high concentrations, especially in the particle-phase. For the nitrated PAH emissions (nitro-PAHs), low molecular weight compounds dominated the cooking emissions. Under the present experimental conditions, the heterocyclic aromatic amines (HAAs) showed very low concentrations, which suggests these species are rarely formed in meat cooking PM. The most efficient control technology for reducing the majority of the toxic pollutants was the electrostatic precipitator, which resulted in total emissions reductions on the order of 95%, 79%, 90%, 96%, 90%, and 94%, respectively, for particle-phase PAHs, gas-phase PAHs, particle-phase nitro-PAHs, gas-phase nitro-PAHs, particle-phase HAAs, and gas-phase HAAs compared to the baseline testing. Our experiment showed that cooking aerosol contained higher levels of prooxidants in the particle-phase and the corresponding vapors contained higher levels of electrophiles. Overall, the use of control technologies reduced the redox and electrophilic activities of cooking PM.

A Chemical Perspective of Pharmacology and Toxicology

My chemical training provided a somewhat different perspective of biolo-gical problems, in the problem itself and approaches to its solution. I was fortunate to have in my laboratory postdocs and students who shared this perspective and used appropriate tools to address problems in amphetamine pharmacology and air pollution toxicology. These apparently disparate areas of research shared two chemical reactions: prooxidant-based generation of reactive oxygen and formation of covalent bonds between electrophiles and biological nucleophiles. This article is an attempt to summarize that research and to identify those individuals who made the contributions.

Impact of biodiesel on regulated and unregulated emissions, and redox and proinflammatory properties of PM emitted from heavy-duty vehicles

The emissions and the potential health effects of particulate matter (PM) were assessed from two heavy-duty trucks with and without emission control aftertreatment systems when operating on CARB ultra-low sulfur diesel (ULSD) and three different biodiesel blends. The CARB ULSD was blended with soy-based biodiesel, animal fat biodiesel, and waste cooking oil biodiesel at 50vol%. Testing was conducted over the EPA Urban Dynamometer Driving Schedule (UDDS) in triplicate for both trucks. The aftertreatment controls effectively decreased PM mass and number emissions, as well as the polycyclic aromatic hydrocarbons (PAHs) compared to the uncontrolled truck. Emissions of nitrogen oxides (NO_x) exhibited increases with the biodiesel blends, showing some feedstock dependency for the controlled truck. The oxidative potential of the emitted PM, measured by means of the dithiothreitol (DTT) assay, showed reductions with the use of biodiesel blends relative to CARB ULSD for the uncontrolled truck. Overall, the cellular responses to the particles from each fuel were reflective of the chemical content, i.e., particles from CARB ULSD were the most reactive and exhibited the highest cellular responses.

An online monitor of the oxidative capacity of aerosols (o-MOCA)

The capacity of airborne particulate matter to generate reactive oxygen species (ROS) has been correlated with the generation of oxidative stress both in vitro and in vivo. The cellular damage from oxidative stress, and by implication with ROS, is associated with several common diseases, such as asthma and chronic obstructive pulmonary disease (COPD), and some neurological diseases. Yet currently available chemical and in vitro assays to determine the oxidative capacity of ambient particles require large samples, analyses are typically done offline, and the results are not immediate. Here we report the development of an online monitor of the oxidative capacity of aerosols (o-MOCA) to provide online, time-resolved assessment of the capacity of airborne particles to generate ROS. Our approach combines the Liquid Spot Sampler (LSS), which collects particles directly into small volumes of liquid, and a chemical module optimized for online measurement of the oxidative capacity of aerosol using the dithiothreitol (DTT) assay. The LSS uses a three-stage, laminar-flow water condensation approach to enable the collection of particles as small as 5 nm into liquid. The DTT assay has been improved to allow the online, time-resolved analysis of samples collected with the LSS but could be adapted to other collection methods or offline analysis of liquid extracts. The o-MOCA was optimized and its performance evaluated using the 9,10-phenanthraquinone (PQ) as a standard redox-active compound. Laboratory testing shows minimum interferences or carryover between consecutive samples, low blanks, and a reproducible, linear response between the DTT consumption rate (nmol min^-1) and PQ concentration (μM). The calculated limit of detection for o-MOCA was 0.15 nmol min^-1. The system was validated with a diesel exhaust particle (DEP) extract, previously characterized and used for the development, improvement, and validation of the standard DTT analysis. The DTT consumption rates (nmol min^-1) obtained with the o-MOCA were within experimental uncertainties of those previously reported for these DEP samples. In ambient air testing, the fully automated o-MOCA was run unattended for 3 days with 3 h time resolution and showed a diurnal and daily variability in the measured consumption rates (nmol min^-1 m^-3).

Paper-based analytical devices for environmental analysis

The field of paper-based microfluidics has experienced rapid growth over the past decade. Microfluidic paper-based analytical devices (μPADs), originally developed for point-of-care medical diagnostics in resource-limited settings, are now being applied in new areas, such as environmental analyses. Low-cost paper sensors show great promise for on-site environmental analysis; the theme of ongoing research complements existing instrumental techniques by providing high spatial and temporal resolution for environmental monitoring. This review highlights recent applications of μPADs for environmental analysis along with technical advances that may enable μPADs to be more widely implemented in field testing.