Characterization of particulate-phase polycyclic aromatic hydrocarbons emitted from incense burning and their bioreactivity in RAW264.7 macrophage

Particulate organic emissions from incense-burning smoke: Chemical compositions and emission characteristics

Incense burning is a common practice in Asian cultures, releasing hazardous particulate organics. Inhaling incense smoke can result in adverse health effects, yet the molecular compositions of incense-burning organics have not been well investigated due to the lack of measurement of intermediate-volatility and semi-volatile organic compounds (I/SVOCs). To elucidate the detailed emission profile of incense-burning particles, we conducted a non-target measurement of organics emitted from incense combustion. Quartz filters were utilized to trap particles, and organics were analyzed by a comprehensive two-dimensional gas chromatography-mass spectrometer (GC × GC-MS) coupled with a thermal desorption system (TDS). To deal with the complex data obtained by GC × GC-MS, homologs are identified mainly by the combination of selected ion chromatograms (SICs) and retention indexes. SICs of 58, 60, 74, 91, and 97 were utilized to identify 2-ketones, acids, fatty acid methyl esters, fatty acid phenylmethyl esters, and alcohols, respectively. Phenolic compounds contribute the most to emission factors (EFs) among all chemical classes, taking up 24.5 % ± 6.5 % of the total EF (96.1 ± 43.1 μg g-1). These compounds are largely derived from the thermal degradation of lignin. Biomarkers like sugars (mainly levoglucosan), hopanes, and sterols are extensively detected in incense combustion fumes. Incense materials play a more important role in shaping emission profiles than incense forms. Our study provides a detailed emission profile of particulate organics emitted from incense burning across the full-volatility range, which can be used in the health risk assessments. The data processing procedure in this work could also benefit those with less experience in non-target analysis, especially GC × GC-MS data processing.

Urinary polycyclic aromatic hydrocarbon metabolites were associated with short sleep duration and self-reported trouble sleeping in US adults: data from NHANES 2005-2016 study population

Background

The aim of the current study was to investigate the link between human exposure to PAHs with short sleep duration (SSD) and self-reported trouble sleeping.

Methods

A total of 9,754 participants and 9,777 participants obtained from NHANES 2005-2016 were included in this cross-sectional study about SSD and self-reported trouble sleeping, respectively. The association between urinary PAHs metabolites with the prevalence of SSD and self-reported trouble sleeping by the weighted multivariate logistic regression model, restricted cubic spline (RCS) curves, and weighted quantile sum (WQS) regression.

Results

After adjusting for all covariates, 1-hydroxynapthalene, 2-hydroxynapthalene, 3-hydroxyfluorene, 2-hydroxyfluorene, 1-hydroxyphenanthrene, and 1-hydroxyphenanthrene demonstrated positive associations with SSD prevalence. Besides, 1-hydroxynapthalene, 2-hydroxynapthalene, 3-hydroxyfluorene, 2-hydroxyfluorene, 1-hydroxyphenanthrene, and 1-hydroxyphenanthrene exhibited positive associations with the prevalence of self-reported trouble sleeping following the adjustment for all covariates. RCS curves confirmed the non-linear associations between 1-hydroxynapthalene, 2-hydroxynapthalene, 3-hydroxyfluorene, 2-hydroxyfluorene, and 1-hydroxyphenanthrene with the prevalence of SSD, and 1-hydroxynapthalene, 3-hydroxyfluorene, and 2-hydroxyfluorene with the prevalence of self-reported trouble sleeping. The WQS results showed that mixed exposure to PAH metabolites had a significant positive association with the prevalence of SSD (OR: 1.087, 95% CI: 1.026, 1.152, p = 0.004) and self-reported trouble sleeping (OR: 1.190, 95% CI: 1.108, 1.278, p < 0.001).

Conclusion

Urinary concentrations of PAH metabolites exhibited a close association with the prevalence of SSD and self-reported trouble sleeping in US adults. More emphasis should be placed on the importance of environmental effects on sleep health.

Tanshinone IIA suppresses burning incense-induced oxidative stress and inflammatory pathways in astrocytes

The burning incense (BI) behavior could be widely observed in Asia families. Incense sticks are often believed to be made from natural herbs and powders, and to have minimal impact on human health; however, there is limited research to support this claim. The current study aimed to identify the components of BI within the particulate matter 2.5 µm (PM_2.5) range and explore if BI has bio-toxicity effects on rat astrocytes (CTX-TNA2). The study also examined the protective effects and underlying molecular mechanisms of tanshinone IIA, a primary lipid-soluble compound found in the herb danshen (Salvia miltiorrhiza Bunge), which has been shown to benefit the central nervous system. Results showed that despite the differences in BI components compared to the atmospheric particulate matter (PM) standards, BI still had a bio-toxicity on astrocytes. BI exposure caused early and late apoptosis, reactive oxygen species (ROS) production, MAPKs (JNK, p38, and ERK), and Akt signaling activation, and inflammation-related proteins (cPLA2, COX-2, HO-1, and MMP-9) increases. Our results further exhibit that the tanshinone IIA pre-treatment could significantly avoid the BI-induced apoptosis and inflammatory signals on rat astrocytes. These findings suggest that BI exposure may cause oxidative stress in rat astrocytes and increase inflammation-related proteins and support the potential of tanshinone IIA as a candidate for preventing BI-related adverse health effects.

Fine particulate matter (PM2.5) induces inhibitory memory alveolar macrophages through the AhR/IL-33 pathway

Fine particulate matter (PM2.5) concentrations have decreased in the past decade. The adverse effects of acute PM2.5 exposure on respiratory diseases have been well recognized. To explore the long-term effects of PM2.5 exposure on chronic obstructive pulmonary disease (COPD), mice were exposed to PM2.5 for 7 days and rest for 21 days, followed by challenges with lipopolysaccharide (LPS) and porcine pancreatic elastase (PPE). Unexpectedly, PM2.5 exposure and rest alleviated the disease severity and airway inflammatory responses in COPD-like mice. Although acute PM2.5 exposure increased airway inflammation, rest for 21 days reversed the airway inflammatory responses, which was associated with the induction of inhibitory memory alveolar macrophages (AMs). Similarly, polycyclic aromatic hydrocarbons (PAHs) in PM2.5 exposure and rest decreased pulmonary inflammation, accompanied by inhibitory memory AMs. Once AMs were depleted, pulmonary inflammation was aggravated. PAHs in PM2.5 promoted the secretion of IL-33 from airway epithelial cells via the aryl hydrocarbon receptor (AhR)/ARNT pathway. High-throughput mRNA sequencing revealed that PM2.5 exposure and rest drastically changed the mRNA profiles in AMs, which was largely rescued in IL-33^-/- mice. Collectively, our results indicate that PM2.5 may mitigate pulmonary inflammation, which is mediated by inhibitory trained AMs via IL-33 production from epithelial cells through the AhR/ARNT pathway. We provide the rationale that PM2.5 plays complicated roles in respiratory disease.

Importance of surface charge of soot nanoparticles in determining inhalation toxicity in mice

Physicochemical properties of nanoparticles are important in regulating nanoparticle toxicity; however, the contribution of nanoparticle charge remains unclear. The objective of this study was to investigate the pulmonary effects of inhalation of charged soot nanoparticles. We established a stably charged nanoparticle generation system for whole-body exposure in BALB/c mice, which produced positively charged, negatively charged, and neutral soot nanoparticles in a wide range of concentrations. After a 7-day exposure, pulmonary toxicity was assessed, together with proteomics analysis. The charged soot nanoparticles on average carried 1.17-1.35 electric charges, and the sizes for nanoparticles under different charging conditions were all fixed at 69 ~ 72 nm. We observed that charged soot nanoparticles induced cytotoxic LDH and increased lung permeability, with the release of 8-isoprostane and caspase-3 and systemic IL-6 in mice, especially for positively charged soot nanoparticles. Next, we observed that positive-charged soot nanoparticles upregulated Eif2, Eif4, sirtuin, mammalian target of rapamycin (mTOR), peroxisome proliferator-activated receptors (PPAR), and HIPPO-related signaling pathways in the lungs compared with negatively charged soot nanoparticles. HIF1α, sirt1, E-cadherin, and Yap were increased in mice's lungs by positively charged soot nanoparticle exposure. In conclusion, carbonaceous nanoparticles carrying electric ions, especially positive-charged, are particularly toxic when inhaled and should be of concern in terms of pulmonary health protection.

Indoor Exposure and Regional Inhaled Deposited Dose Rate during Smoking and Incense Stick Burning-The Jordanian Case as an Example for Eastern Mediterranean Conditions

Tobacco smoking and incense burning are commonly used in Jordanian microenvironments. While smoking in Jordan is prohibited inside closed spaces, incense burning remains uncontrolled. In this study, particle size distributions (diameter 0.01-25 µm) were measured and inhaled deposited dose rates were calculated during typical smoking and incense stick-burning scenarios inside a closed room, and the exposure was summarized in terms of number and mass concentrations of submicron (PN_Sub) and fine particles (PM_2.5). During cigarette smoking and incense stick-burning scenarios, the particle number concentrations exceeded 3 × 10⁵ cm^-3. They exceeded 5 × 10⁵ cm^-3 during shisha smoking. The emission rates were 1.9 × 10¹⁰, 6.8 × 10¹⁰, and 1.7 × 10¹⁰ particles/s, respectively, for incense, cigarettes, and shisha. That corresponded to about 7, 80, and 120 µg/s, respectively. Males received higher dose rates than females, with about 75% and 55% in the pulmonary/alveolar during walking and standing, respectively. The total dose rates were in the order of 10¹²-10¹³ #/h (10³-10⁴ µg/h), respectively, for PN_Sub and PM_2.5. The above reported concentrations, emissions rates, and dose rates are considered seriously high, recalling the fact that aerosols emitted during such scenarios consist of a vast range of toxicant compounds.

Health and Environmental Risks of Incense Smoke: Mechanistic Insights and Cumulative Evidence

Incense burning is practiced alongside many sacred rituals across different regions of the world. Invariable constituents of incense brands are 21% (by weight) herbal and wood powder, 33% bamboo stick, 35% fragrance material, and 11% adhesive powder. Major incense-combustion outputs include particulate matter (PM), volatile organic content, and polyaromatic hydrocarbons. The relative toxicity of these products is an implicit function of particle size and incomplete combustion, which in turn vary for a specific incense brand. Lately, the attention given to the Air Quality Index by international regulatory bodies has created concern about mounting PM toxicity. The uncharacteristically small physical dimensions of these entities complicates their detection, and with no effect of gravity PM fractions rapidly contribute to oxidative stress, enhancing random biochemical reactions upon being inhaled. Incense burning generates four times the PM extent (45 mg•g⁻¹) of cigarettes (~10 mg•g⁻¹). Several poisonous gases, such as CO, CO₂, NO₂, and SO₂, and the unavoidable challenge of disposing of the burnt incense ash further add to the toxicity. Taken together, these issues demonstrate that incense burning warrants prompt attention. The aim of this article is to highlight the toxicity of incense-combustion materials on the environment and human health. This discussion could be significant in framing future policy regarding ecofriendly incense manufacture and reduced usage.

Source identification and health risk assessments of polycyclic aromatic hydrocarbons in settled dusts from different population density areas of Ilorin, Nigeria

Polycyclic aromatic hydrocarbons (PAHs) have attracted significant attention in recent times on account of their reasonably high environmental burden and extreme toxicity. Samples of indoor dusts were obtained daily over a period of 2 weeks from 10 residences located within low, medium, and high density residential areas of Ilorin City. The concentration levels, potential sources, and cancer health risks of sixteen polycyclic aromatic hydrocarbons (PAHs) were investigated using gas chromatography/mass spectrometry. PAHs total concentrations varied from 3.95 ± 0.19 to 8.70 ± 0.43 μg/g with arithmetic mean of 6.09 ± 0.46 μg/g. Fluoranthene was the most dominant PAHs congener. High molecular weight (HMW) PAHs (4-6 rings) were the most prevalent PAHs and were responsible for 79.29% of total PAHs in sampled residences. Chrysene (Chry) was the most abundant compound among the 7 carcinogenic PAHs (CPAHs). Moreover, diagnostic ratios and positive matrix factorization (PMF) employed to apportion PAHs suggested that indoor dusts originated from indoor activities and infiltrating outdoor air pollutants. Diagnostic ratios revealed that PAHs are from mixed sources which include coal/wood combustion, non-traffic and traffic emissions, petroleum, petrogenic (gasoline), and petroleum combustion. Similarly, positive matrix factorization (PMF) model suggested five sources (factors) were responsible for PAHs in indoor dusts comprised of petroleum combustion and traffic emissions (60.05%), wood and biomass combustion emissions (20.84%), smoke from cooking, incense burning and tobacco (4.17%), gasoline combustion from non-traffic sources (13.89%), and emissions from coal burning and electronic devices (1.05%). The incremental lifetime carcinogenic risks (ILCR) of PAHs in adults and children estimated by applying benzo(a)pyrene (BaP) equivalent were within the satisfactory risk limits in Ilorin. Indoor PAHs emissions in Ilorin residences could be monitored and controlled by using data provided in this study.

Human health-risk assessment based on chronic exposure to the carbonyl compounds and metals emitted by burning incense at temples

Health effects resulting from the smoke of carbonyl compounds (aldehydes and ketones) and metal-containing incense particles at temples during incense burning periods were evaluated at temple A (without incense reduction activities) and B (with incense reduction activities), Nantou County, in 2018. The predominant size fractions of particles were PM₁, PM_1-2.5, and PM_2.5-10 at both temples. The total particle mass at temple A was approximately 1.1 times that of temple B due to incense reduction at temple B. The most abundant metal elements in all particle size fractions at both temples were Fe, Al, and Zn. Metal species of incense smoke are divided into three groups by hierarchical cluster analysis and heatmaps, showing higher metal contents in groups PM₁, PM_18-10, and PM_18-2.5 at temple A. In contrast, higher metal contents were observed in PM_18-10 and PM_2.5-1 at temple B. Most of the carbonyl species were formaldehyde and acetaldehyde, released during incense burning periods, with concentrations ranging from 6.20 to 13.05 μg/m³ at both temples. The total deposited fluxes of particle-bound metals at temples A and B were determined to be 83.00% and 84.82% using the International Commission on Radiological Protection (ICRP) model. Health-risk assessments revealed that the risk values of metals and carbonyls were above recommended guidelines (10^-6) at temple A. Since worshippers and staff are exposed to incense burning environments with poor ventilation over a long period, these toxic organic compounds and metals increase health risks in the respiratory tract. Therefore, incense reduction is important to achieve healthy temple environments.

Multi-response optimization toward efficient and clean (co-)combustions of textile dyeing sludge and second-generation feedstock

The rapid growth of textile dyeing sludge (TDS) necessitates feeding it back into a circular economy in an efficient and clean way. This study aimed to optimize the clean and efficient operational conditions to co-combust TDS and incense sticks (IS). The (co-)-combustions exhibited four distinctive stages of thermal degradation. According to the master-plots method, the reaction mechanisms of reaction order (F2.4 and F1.5), three-dimensional diffusion (D3), and nucleation growth (A1.5) best explained the four stages, respectively. The interaction between TDS and IS exerted an inhibition effect in the range of 400-500 °C and a facilitation effect in the range of 600-1000 °C. At 300 °C as the main reaction temperature, the main evolved gas and functional groups such as CO₂, H₂O, CH₄, C˭O, C-O, and C-H were detected. The addition of IS improved the comprehensive combustion index, inhibited SO₂, but enhanced CO₂, HCN, and NO_x emissions. CaO in IS enabled Fe to remain in TDS and fixed more S in ash. Multi-response optimizations based on the best-fit artificial neural networks revealed the range of 545-605 °C and the co-combustion of 25% TDS and 75% IS as the cleaner and more efficient operational conditions.

Lead poisoning due to incense burning: an outbreak in a family

BACKGROUND

In Asia and some other regions of the world, incense burning is an important folk and cultural activity. However, this ritual can cause health impacts, such as chronic respiratory diseases and neoplasms. Herein, we describe a family with lead poisoning possibly related to the frequent use of incense sticks at home.

CASE REPORT

A 65-year-old homemaker with severe anemia, pitting edema of the lower legs, bone pain, abdominal pain, and exertional dyspnea for several months presented to our clinic. Her blood workup indicated severe anemia with basophilic stippling in red blood cells and blood lead level (BLL) of 59.75 μg/dL. Her husband, three children, and four grandchildren who lived with her also had high BLLs. As a Daoist clergy person, she had been exposed to a large amount of smoke from every day use of incense for >30 years. In the field investigation, the chronic dust deposited in hidden corners of their home had considerably higher lead content and other toxic metals.

DISCUSSION

Our observations indicated chronic, frequent exposure to smoke from incense burning may be a cause of lead poisoning. Strict avoidance of incense smoke is a significant step toward preventing lead poisoning in children in societies with the custom of incense burning.

Particulate matters induce acute exacerbation of allergic airway inflammation via the TLR2/NF-κB/NLRP3 signaling pathway

BACKGROUND

Exposure to particulate matters (PMs) can lead to an acute exacerbation of allergic airway diseases, increasing the severity of symptoms and mortality. However, little is known about the underlying molecular mechanism. This study aimed to investigate the effects of PMs on acute exacerbation of allergic airway inflammation and seek potential therapeutic targets.

METHODS

Non-allergic control and ovalbumin (OVA)-allergic wide-type (WT) and Toll-like receptor 2 knockout (Tlr2-/-) mice were exposed to 100 μg of PM (diameter 5.85 μm) or saline by the oropharyngeal instillation. The responses were examined three days after exposure. In the RAW264.7 macrophage cell line, Tlr2 was knocked down by small-interfering RNA or the NF-κB inhibitor JSH-23 was used, and then the cells were stimulated with PMs for 12 h before comparison of the inflammatory responses.

RESULTS

PM exposure led to increased inflammatory cell recruitment and airway intensity of PAS + staining in OVA-allergic WT mice, accompanied with an accumulation of inflammatory cells and elevated inflammatory cytokines, such as IL-6 and IL-18, in the bronchoalveolar lavage fluid (BALF). Furthermore, the protein levels of TLR2 and the NLRP3 inflammasome were elevated concomitantly with the airway inflammation post-OVA/PMs challenge. Tlr2 deficiency effectively inhibited the airway inflammation, including pulmonary inflammatory cell recruitment, mucus secretion, serum OVA-specific immunoglobulin E (IgE), and BALF inflammatory cytokine production. Additionally, the P-induced NLRP3 activation in the RAW 264.7 cell line was diminished by the knockdown of Tlr2 or JSH-23 treatment in vitro.

CONCLUSION

Our results indicated that PMs exacerbate the allergic airway inflammation mediated by the TLR2/ NF-κB/NLRP3 signaling pathway. Inhibition of NF-κB seems to be a possible treatment.

Investigation of inflammation inducing substances in PM2.5 particles by an elimination method using thermal decomposition

The substances associated with PM2.5-induced inflammatory response were investigated using an elimination method. PM2.5 were heated at temperatures of 120, 250, and 360°C. The results demonstrated microbial substances such as LPS and b-glucan, and chemicals including BaP, 1,2-NQ, and 9,10-PQ were reduced drastically in PM2.5 heated at 120°C. On the other hand, DBA, 7,12-BAQ, and BaP-1,6-Q were not noticeably reduced. Most of these substances had disappeared in PM2.5 heated at 250°C and 360°C. Metals (eg, Fe, Cu, Cr, Ni) in PM2.5 exhibited a slight thermo-dependent increase. RAW264.7 macrophages with or without NAC were exposed to unheated PM2.5, oxidative stress-related and unrelated inflammatory responses were induced. PM2.5-induced lung inflammation in mice is caused mainly by thermo-sensitive substances (LPS, b-glucan, BaP, 1,2-NQ, 9,10-PQ, etc.). Also, a slight involvement of thermo-resistant substances (DBA, 7,12-BAQ, BaP-1,6-Q, etc.) and transition metals was observed. The thermal decomposition method could assist to evaluate the PM2.5-induded lung inflammation.

Associations between inhaled doses of PM2.5-bound polycyclic aromatic hydrocarbons and fractional exhaled nitric oxide

Exposure to fine particulate matter (PM_2.5) is linked to various respiratory outcomes. However, the associations of concentrations of PM_2.5-bound polycyclic aromatic hydrocarbons (PM_2.5-bound PAHs) with airway inflammatory indices remains unclear. To assess effects of short-term exposure to PM_2.5-bound PAHs on fractional exhaled nitric oxide (FeNO), we conducted a pilot study with repeated measures. We recruited 20 postgraduate students in Wuhan city, China, and repeatedly measured outdoor and indoor (including dormitories, offices and laboratories) PM_2.5-bound PAHs concentrations, urinary monohydroxy polycyclic aromatic hydrocarbons (OH-PAHs) and FeNO levels in the four seasons. Subsequently, we estimated inhaled doses of PM_2.5-bound PAHs based on the micro-environmental PM_2.5-bound PAHs concentrations, time-activity patterns and referred inhalation rates. We assessed the association of inhaled doses of PM_2.5-bound PAHs with FeNO using linear mixed-effects regression models. We found the positive associations of urinary ∑OH-PAHs levels with inhaled doses of indoor PM_2.5-bound PAHs (including dormitories and offices) (all p < 0.05). A one-unit increase in inhaled doses of PM_2.5-bound PAHs or in urinary concentrations of ∑OH-PAHs was corresponded to a maximum FeNO increase of 13.5% (95% CI: 5.4, 22.2) at lag2 day or of 6.8% (95% CI: 3.4, 10.2) at lag1 day. Inhaled doses of PM_2.5-bound PAHs or urinary OH-PAHs was positively related to increased FeNO, they may be accepted as a short-term biomarker of exposure to PAHs in air. Exposure to PM_2.5-bound PAHs in indoor air may contribute more to the body burden of PAHs than outdoor air, and exhibited stronger effect on increased FeNO rather than urinary OH-PAHs.