IN VITRO EFFECTS OF WATER-SOLUBLE METALS PRESENT IN UK PARTICULATE MATTER

Particle-induced oxidative damage by indoor size-segregated particulate matter from coal-burning homes in the Xuanwei lung cancer epidemic area, Yunnan Province, China

Size-segregated samples of airborne particulate matter were collected at the coal-burning homes of the Hutou high lung cancer epidemic village and a comparison site Xize village of the Xuanwei County, Yuanan Province, by an Anderson Cascade Impact Sampler in winter and spring to study the toxicological characteristics of different-sized particles. The DNA damage caused by the water-soluble fractions of these size-segregated particles was analyzed by the plasmid scission assay, and the trace element compositions were determined by Inductively Coupled Plasma Mass Spectrometry. The DNA damage rate from the airborne particles in the high lung cancer incidence area was higher than that in Xize village. The different-sized particles have highly varying DNA damage rates, with the values being greater in the small size range than in the large size range. The particle-induced DNA damage rates had a significantly positive correlation with total water-soluble trace elements. Further analysis of the individual elements indicated that the water-soluble heavy metals Zn, Cu, Cd, Rb, Cs, and Sb had a positive correlation with the particle-induced DNA damage, implying that these water-soluble heavy metals played an important role in the DNA damage. The Sr had a negative correlation with the particle-induced DNA damage, suggesting that the water-soluble Sr might counter DNA damage. The mass concentrations of the total and individual water-soluble trace elements were mostly enriched in the small particle size ranges, thus implying the indoor airborne particles in the small size ranges would have a higher health risk.

Associations of soluble metals and lung and liver toxicity in mice induced by fine particulate matter originating from a petrochemical complex

Adverse health effects have been observed in nearby residents due to exposure to petrochemical-derived chemicals. The objective of this study was to examine associations of soluble metals with lung and liver toxicity in fine particulate matter (PM2.5) in the vicinity of a petrochemical complex. PM2.5 was collected in the vicinity of a petrochemical complex of Mailiao Township (Yunlin County, Taiwan) to investigate lung and liver toxicity in BALB/c mice. The PM2.5 concentration was 30.2 ± 11.2 μg/m3, and the PM2.5 was clustered in major local emissions (19.1 μg/m3) and minor local emissions (14.1 μg/m3) using a k-means clustering model. The PM2.5 (50 and 150 μg/kg) and PM2.5-equivalent soluble nickel (Ni), vanadium (V), and lead (Pb) concentrations were intratracheally instilled into BALB/c mice. PM2.5 and V significantly decreased the tidal volume after exposure (p < 0.05). The peak expiratory flow (PEF) and peak inspiratory flow (PIF)/PEF ratio were significantly altered by 150 μg/kg V (p < 0.05). V and Pb significantly increased total protein and lactate dehydrogenase (LDH) levels in bronchoalveolar lavage fluid (BALF) (p < 0.05). Interleukin (IL)-6 in BALF significantly increased after exposure to Pb (p < 0.05) accompanied by lung inflammatory infiltration. PM2.5 and Pb significantly increased levels of 8-isoprostane (p < 0.05). The level of caspase-3 activity significantly increased after exposure to Pb (p < 0.05). LDH in the liver was significantly increased by PM2.5 (p < 0.05). 8-Isoprostane in the liver was significantly increased by PM2.5 and Pb (p < 0.05). IL-6 in the liver was significantly increased by PM2.5, Ni, V, and Pb after exposure (p < 0.05), accompanied by liver inflammatory infiltration. Our results demonstrated that V in PM2.5 was associated with an increase in 8-isoprostane for all emissions and major local petrochemical emissions. In conclusion, V contributes to in vivo liver toxicity induced by PM2.5 in the vicinity of a petrochemical complex.

Seasonal variation of particle-induced oxidative potential of airborne particulate matter in Beijing

An in vitro plasmid scission assay (PSA), the cell apoptosis assay, and ICP-MS were employed to study the oxidative potentials and trace element compositions of the airborne particulate matter (PM) in Beijing during a one year-long field campaign from June 2010 to June 2011. The cell damages induced by PM reveled by the cell apoptosis assay showed a similar variation pattern to the DNA damages obtained by PSA, verifying the feasibility of the PSA in analyzing the oxidative capacity of PM samples. The PSA experiments showed that the particle-induced DNA damage was highest in summer, followed by spring, winter and autumn in descending order. The percentages of the oxidative damages to plasmid DNA induced by the water-soluble fractions of PM under the particle doses from 10 to 250μg/ml were generally lower than 45%, with some values peaking at above 50%. The peak values were frequently present in late spring (i.e. April and May) and early summer (i.e. June) but they were scarcely observed in other seasons. These peak values were mostly associated with haze days or the days with low wind speed (less than 4m/s), indicating that the PM samples during haze had higher oxidative potential than those during non-haze periods. The oxidative potential induced by the water-soluble fraction of the PM displayed a significant positive correlation with the concentrations of the water-soluble elements Cd, Cs, Pb, Rb, Zn, Be and Bi, demonstrating that the particle-induced oxidative potentials were mainly sourced from these elements. The exposure risk represented by the mass concentration of these elements in unit volume of atmosphere was higher in summer and winter, and lower in autumn and spring. The haze day PM samples not only had higher level of oxidative potentials but also had higher concentrations of water-soluble elements.

PM10 mass concentration and oxidative capacity of moxa smoke

BACKGROUND

The burning of moxa floss in moxibustion releases moxa smoke containing a substantial amount of particulate matter (PM10) into the environment, which has generated safety concerns about its potential health impact.

DESIGN

Plasmid scission assay was performed using PM10 collected from moxibustion clinics.

METHODS

PM10 was collected in winter 2012 by burning three types of moxa floss samples in moxibustion simulation clinics, and the resulting PM10 mass concentration was calculated. Oxidative capacity of the PM10 samples was measured by plasmid scission assay and the percentage of DNA damage at dosage 500 µg ml(-1) (D500) was calculated by linear regression analysis.

RESULTS

The average PM10 mass concentration of samples A (3 years and 3:1 ratio), B (3 years and 8:1 ratio) and C (10 years and 3:1 ratio) was 273.33, 172.22 and 168.89 μg/m(3), respectively. The D500 oxidative capacity of PM10 was on average 24.25%, 27.83% and 28.07% for samples A, B and C, respectively. No significant difference was found in the PM10-induced oxidative damage by moxa smoke produced from the three types of moxa floss.

CONCLUSIONS

PM10 mass concentrations from the three types of moxa floss combustion exceeded internationally recommended levels. Despite so, PM10 mass concentration of moxa smoke was much lower than biomass and coal combustion and similar to that of gas combustion. The oxidative DNA damage induced by individual PM10 in moxibustion environment was lower than that reported in other environments, indicating that moxibustion-derived PM10 might not be as injurious to human health as generally assumed.

Contrasts in spatial and temporal variability of oxidative capacity and elemental composition in moxibustion, indoor and outdoor environments in Beijing

Moxibustion is a traditional Chinese medicine therapy that burns moxa floss which produces a substantial amount of PM10 into the environment, thus spawning safety concerns about health impacts of the smoke. We compared the oxidative capacity and elemental composition of moxibustion-derived and ambient PM10 in summer and winter to provide a source-, spatial- and temporal-comparison of PM10 biological responses. The PM10 oxidative capacity was 2.04 and 1.45 fold lower, and dose-dependent slope gradient was 2.36 and 1.76 fold lower in moxibustion environment than indoor or outdoor. Oxidative damage was highly correlated with iron, cesium, aluminum and cobalt in indoor, but moxibustion environment displayed low associations. The total elemental concentration was also lower in moxibustion environment than indoor (2.28 fold) or outdoor (2.79 fold). The source-to-dose modeling and slope gradient analysis in this study can be used as a model for future source-, spatial- and temporal-related moxibustion safety evaluation studies.

Physicochemical characterization of airborne particulate matter at a mainline underground railway station

Underground railway stations are known to have elevated particulate matter (PM) loads compared to ambient air. As these particles are derived from metal-rich sources and transition metals may pose a risk to health by virtue of their ability to catalyze generation of reactive oxygen species (ROS), their potential enrichment in underground environments is a source of concern. Compared to coarse (PM10) and fine (PM2.5) particulate fractions of underground railway airborne PM, little is known about the chemistry of the ultrafine (PM0.1) fraction that may contribute significantly to particulate number and surface area concentrations. This study uses inductively coupled plasma mass spectrometry and ion chromatography to compare the elemental composition of size-fractionated underground PM with woodstove, roadwear generator, and road tunnel PM. Underground PM is notably rich in Fe, accounting for greater than 40% by mass of each fraction, and several other transition metals (Cu, Cr, Mn, and Zn) compared to PM from other sources. Importantly, ultrafine underground PM shows similar metal-rich concentrations as the coarse and fine fractions. Scanning electron microscopy revealed that a component of the coarse fraction of underground PM has a morphology indicative of generation by abrasion, absent for fine and ultrafine particulates, which may be derived from high-temperature processes. Furthermore, underground PM generated ROS in a concentration- and size-dependent manner. This study suggests that the potential health effects of exposure to the ultrafine fraction of underground PM warrant further investigation as a consequence of its greater surface area/volume ratio and high metal content.

Use of X-ray absorption spectroscopy to speciate manganese in airborne particulate matter from five counties across the United States

The purpose of this study is to characterize manganese oxidation states and speciation in airborne particulate matter (PM) and describe how these potentially important determinants of PM toxicity vary by location. Ambient PM samples were collected from five counties across the US using a high volume sequential cyclone system that collects PM in dry bulk form segregated into "coarse" and "fine" size fractions. The fine fraction was analyzed for this study. Analyses included total Mn using ICP-MS and characterization of oxidation states and speciation using X-ray absorption spectroscopy (XAS). XAS spectra of all samples and ten standard compounds of Mn were obtained at the National Synchrotron Light Source. XAS data was analyzed using Linear Combination Fitting (LCF). Results of the LCF analysis describe differences in composition between samples. Mn(II) acetate and Mn(II) oxide are present in all samples, while Mn(II) carbonate and Mn(IV) oxide are absent. To the best of our knowledge, this is the first paper to characterize Mn composition of ambient PM and examine differences between urban sites in the US. Differences in oxidation state and composition indicate regional variations in sources and atmospheric chemistry that may help explain differences in health effects identified in epidemiological studies.

Soot-driven reactive oxygen species formation from incense burning

This study investigated the effects of reactive oxygen species (ROS) generated as a function of the physicochemistry of incense particulate matter (IPM), diesel exhaust particles (DEP) and carbon black (CB). Microscopical and elemental analyses were used to determine particle morphology and inorganic compounds. ROS was determined using the reactive dye, Dichlorodihydrofluorescin (DCFH), and the Plasmid Scission Assay (PSA), which determine DNA damage. Two common types of soot were observed within IPM, including nano-soot and micro-soot, whereas DEP and CB mainly consisted of nano-soot. These PM were capable of causing oxidative stress in a dose-dependent manner, especially IPM and DEP. A dose of IPM (36.6-102.3μg/ml) was capable of causing 50% oxidative DNA damage. ROS formation was positively correlated to smaller nano-soot aggregates and bulk metallic compounds, particularly Cu. These observations have important implications for respiratory health given that inflammation has been recognised as an important factor in the development of lung injury/diseases by oxidative stress. This study supports the view that ROS formation by combustion-derived PM is related to PM physicochemistry, and also provides new data for IPM.

Exploratory investigation of the chemical characteristics and relative toxicity of ambient air particulates from two New Zealand cities

We examined the chemical composition and biological response associated with particulate emissions from the two largest cities in New Zealand, Auckland and Christchurch. The organic and water-soluble fractions were isolated from the particulate matter (PM). The organic fraction was examined for PAH content, direct mutagenicity, CYP1A1 induction, and cytotoxicity and TNF-alpha release in RAW264.7 macrophages. The water-soluble fraction was examined for metal content, and cytotoxicity and TNF-alpha release in RAW264.7 macrophages. Particulate, PAH and water-soluble metal concentrations were all higher in PM collected from Christchurch, being highest in May-July when woodburners for home heating are widely in use. In contrast, PM from Auckland showed the highest concentrations in March, but PAH and metal concentrations were highest in July. We found marked differences in the biological response elicited by ambient air PM: the organic extracts of Christchurch PM(2.5) and PM(10) showed higher mutagenicity and CYP1A1 induction compared with PM(10) from Auckland. In contrast, water-soluble extracts of Auckland PM were more cytotoxic and resulted in greater TNF-alpha release than those from Christchurch PM, although they had a lower metal content. The organic fraction of PM from both cities did not induce any cytokine release, and the organic extract from Auckland samples showed no cytotoxicity; smaller PM mass was available for testing for these samples. Biological responses typically occurred at lower doses of the organic extract, indicating that organic components may be more important in eliciting effects than water-soluble components. Preliminary apportionment of the biological responses to the dominant sources of PM in both cities-woodburners and vehicles-was undertaken. This indicated that for both cities, vehicles have a greater contribution to the direct mutagenic activity of ambient PM than woodsmoke, despite a lower contribution to ambient PM. In contrast, woodsmoke is estimated to have a greater contribution to CYP1A1 induction of ambient PM. The calculated activity forms only a small proportion of the activity observed in extracts of ambient PM from Christchurch, particularly for mutagenicity, and may indicate a significant influence of atmospheric transformation processes on biological response. Only data for mutagenicity and CYP1A1 activity could be used for apportionment as low and/or variable cytotoxicity or TNF-alpha release response were obtained for either the individual source or ambient PM at the doses tested. Further, in the case of the water-soluble extracts from Auckland, additional components are suggested to have a role in the observed activity.

Biomass fuel use and indoor air pollution in homes in Malawi

Background:

Air pollution from biomass fuels in Africa is a significant cause of mortality and morbidity both in adults and children. The work describes the nature and quantity of smoke exposure from biomass fuel in Malawian homes.

Methods:

Markers of indoor air quality were measured in 62 homes (31 rural and 31 urban) over a typical 24 h period. Four different devices were used (one gravimetric device, two photometric devices and a carbon monoxide (HOBO) monitor. Gravimetric samples were analysed for transition metal content. Data on cooking and lighting fuel type together with information on indicators of socioeconomic status were collected by questionnaire.

Results:

Respirable dust levels in both the urban and rural environment were high with the mean (SD) 24 h average levels being 226 μg/m³ (206 μg/m³). Data from real-time instruments indicated respirable dust concentrations were >250 μg/m³ for >1 h per day in 52% of rural homes and 17% of urban homes. Average carbon monoxide levels were significantly higher in urban compared with rural homes (6.14 ppm vs 1.87 ppm; p<0.001). The transition metal content of the smoke was low, with no significant difference found between urban and rural homes.

Conclusions:

Indoor air pollution levels in Malawian homes are high. Further investigation is justified because the levels that we have demonstrated are hazardous and are likely to be damaging to health. Interventions should be sought to reduce exposure to concentrations less harmful to health.

Analysis of crystalline phases in airborne particulate matter by two-dimensional X-ray diffraction (XRD2)

In this work, the potentiality of two-dimensional X-ray diffraction (XRD(2)) to characterise aerosol particles collected on commercial glass filters is presented. Indeed, even if routine analysis usually requires only mass determination, and rarely chemical composition, phase determination is fundamental to recognize the primary or secondary origin of the particulate matter and thus to determine the main sources of the pollution and to model contamination events. The experiments were performed at Daresbury Synchrotron (UK) Laboratory on 14.1 Beamline. The analysis of filters collected in Tuscany (Italy) is discussed with particular attention to the presence of arsenic sulfide. The first results of these experiments are very promising, showing the presence of unexpected compounds in the particulate matter of the investigated area.

Metal release from stainless steel particles in vitro-influence of particle size

Human inhalation of airborne metallic particles is important for health risk assessment. To study interactions between metallic particles and the human body, metal release measurements of stainless steel powder particles were performed in two synthetic biological media simulating lung-like environments. Particle size and media strongly influence the metal release process. The release rate of Fe is enhanced compared with Cr and Ni. In artificial lysosomal fluid (ALF, pH 4.5), the accumulated amounts of released metal per particle loading increase drastically with decreasing particle size. The release rate of Fe per unit surface area increases with decreasing particle size. Compared with massive sheet metal, fine powder particles (<4 microm) show similar release rates of Cr and Ni, but a higher release rate of Fe. Release rates in Gamble's solution (pH 7.4), for all powders investigated, are significantly lower compared to ALF. No clear trend is seen related to particle size in Gamble's solution.