Senlin Lu

Comparison of cellular toxicity caused by ambient ultrafine particles and engineered metal oxide nanoparticles

ObjectiveThe development of nanotechnology has spurred concerns about the health effects of exposure to nanoparticles (NPs) and ultrafine particles (UFPs). Toxicological data on NPs and UFPs may provide evidence to support the development of regulations to reduce the risk of particle exposure. We tried to provide fundamental data to determine differences in cytotoxicity induced by ambient UFPs and engineered metal oxide NPs (ZnO, NiO, and CeO2).MethodsUFPs were sampled by using of a nano micro-orifice uniform deposit impactor. Physicochemical characterization of the UFPs and nano metal oxide particles were studied by scanning electron microscopy and transmission electron microscopy. Cellular toxicity induced by the different particles was assessed by using of comprehensive approaches and compared after A549 cells were exposured to the particles.ResultsAll of the measured particles could damage A549 cells at concentrations ranging from 25 to 200 μg/mL. The lowest survival ratio and the highest lactate dehydrogenase level were caused by nano-ZnO particles, but the highest levels of intracellular reactive oxygen species (ROS) and percentages of apoptosis were observed in cells treated with the soluble fraction of ambient fine particles (PM1.8) at 200 μg/mL. Relatively high concentrations of anthropogenic metals, including Zn, Ni, Fe, and Cu, may be responsible for the higher toxicity of fine ambient particles compared with the ambient coarse particles and UFPs. The selected heavy metals (Zn, Ni, Fe, and Cu) were found to be located in the perinuclear and cytoplasmic areas of A549 cells. The distribution pattern of metals from ambient particles showed that distributions of the metals in A549 cells were not uniform and followed the pattern Cu > Zn > Fe > Ni, suggesting that Cu was absorbed by A549 cells more easily than the other metals.ConclusionsMetal nanoparticles oxides and UFPs at low concentration could damage to cells, but the manufactured metal oxide nanoparticles are not highly toxic to lung cells compared to environmental particles. The local concentration effect of heavy metals in A549 cells, as well as the induction of oxidative stress by the particles, may be responsible for the damage observed to the cells.

Size distribution of chemical elements and their source apportionment in ambient coarse, fine, and ultrafine particles in Shanghai urban summer atmosphere

Ambient coarse particles (diameter 1.8-10 microm), fine particles (diameter 0.1-1.8 microm), and ultrafine particles (diameter < 0.1 microm) in the atmosphere of the city of Shanghai were sampled during the summer of 2008 (from Aug 27 to Sep 08). Microscopic characterization of the particles was investigated by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX). Mass concentrations of Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Rb, Sr, and Pb in the size-resolved particles were quantified by using synchrotron radiation X-ray fluorescence (SRXRF). Source apportionment of the chemical elements was analyzed by means of an enrichment factor method. Our results showed that the average mass concentrations of coarse particles, fine particles and ultrafine particles in the summer air were 9.38 +/- 2.18, 8.82 +/- 3.52, and 2.02 +/- 0.41 microg/m3, respectively. The mass percentage of the fine particles accounted for 51.47% in the total mass of PM10, indicating that fine particles are the major component in the Shanghai ambient particles. SEM/EDX results showed that the coarse particles were dominated by minerals, fine particles by soot aggregates and fly ashes, and ultrafine particles by soot particles and unidentified particles. SRXRF results demonstrated that crustal elements were mainly distributed in the coarse particles, while heavy metals were in higher proportions in the fine particles. Source apportionment revealed that Si, K, Ca, Fe, Mn, Rb, and Sr were from crustal sources, and S, Cl, Cu, Zn, As, Se, Br, and Pb from anthropogenic sources. Levels of P, V, Cr, and Ni in particles might be contributed from multi-sources, and need further investigation.

Size distribution and sources of 37 toxic species of particulate polycyclic aromatic hydrocarbons during summer and winter in Baoshan suburban area of Shanghai, China

The objectives of this study were to assess the size-segregated distribution and sources of 37 different species of particulate polycyclic aromatic hydrocarbons (PAHs) in a suburban area of Shanghai metropolitan City, China. The ambient particulate sampling was carried out on the rooftop of a five-stories building in Baoshan campus of Shanghai University. An Andersen high-volume air sampler was employed to collect ambient size-segregated particulate matter during summer of August to September and winter of November to December 2015. The high toxic PAHs were determined by a gas chromatography mass spectrometry. The concentrations of total PAHs in suspended particulate matter (SPM) and PM1.1 (suspended particulate matter below 1.1μm in diameter) in the suburban area of Shanghai were 4.58-14.5ng/m(3) and 1.82-8.56ng/m(3), respectively in summer, and 43.6-160ng/m(3) and 23.2-121ng/m(3), separately in winter. 1,8-Naphthalic anhydride (1,8-NA) showed the highest concentration among 37 different species of PAHs in the suburban area of Shanghai. The concentrations of high molecular PAHs (e.g. 5-6 ring PAHs) followed a nearly unimodal size distribution with the highest peaks in PM1.1. The diagnostic ration qualitatively indicated that PAHs in SPM of Shanghai were mainly derived from motor-vehicle or petroleum combustion in summer and from coal and biomass combustion in winter. According to the calculated toxicity equivalency factors based on the methods of Nisbet and Lagoy and the potency equivalency factors (PEF) recommended by U.S. EPA, the highest contributors in the total carcinogenicity of the PAHs in SPM and PM1.1 were dibenzo[a,h]pyrene (46.2% and 45.0% in summer), benzo[a]pyrene (44.4% and 43.8% in winter) and benz[j]aceanthrylene (80.2% and 83.1% in summer and 83.1% and 84.0% in winter), respectively. Therefore, benzo[a]pyrene seemed to be a lower contributor than other carcinogenic PAHs.

Speciation of major heavy metals in ambient fine particles collected in the atmospheres of Xuanwei, Yunan, a higher lung incidence area in China

Xuan Wei area, Yunnan province of China, has one of the highest lung cancer mortality rates in China. Heavy metals in the aerosol are potential facts that might attribute to the cause of lung cancer, and speciation of heavy metals could play a key role in toxicity of heavy metals. Therefore, we try to reveal speciation of major heavy metals by using of synchrotron radiation techniques in this study. Mass concentration of chemical elements in ambient particles were analyzed by PIXE (Proton induced X-ray emission), and speciation of Cu was investigated by XAFS (X-ray absorption near-edge structure). Our results demonstrated that mass levels of heavy metals ranked as Fe (791.62 ng/m3) >Zn (479.49 ng/m3) >Pb(154.76 ng/m 3 ) >Cu(28.51 ng/m 3 ) >Co (11.79 ng/m 3 ) >Ni (8.20 ng/m 3 ). The Cu speciation in the different size fraction was different. Speciation of Cu in fine particles (PM0.56~0.32 ) is present as Cu (I), and significant amount of Cu is present as Cu (II) in the ultrafine particles (PM 0.1).

RELEASE BEHAVIOUR OF CRYPTOMERIA JAPONICA POLLEN ALLERGENIC CRY J 1 AND CRY J 2 IN RAINWATER CONTAINING AIR POLLUTANTS

Japanese cedar (Cryptomeria japonica) pollinosis is the most popular pollinosis in Japan. In recent years, it was reported that the most Cryptomeria japonica pollen allergenic species were scattered as fiparticles in the urban atmosphere. It is thought that allergenic fi ne particles are responsible for inducing asthma by breaking into lower respiratory tract; this phenomenon was observed in fiinvestigations during sunny days after rainfall. Hence, it is considered that the release of fiallergenic species derived from pollen grains may be induced during rainfall events. For this reason, we investigated the releasing behaviour of Cryptomeria japonica pollen allergenic species in rainwater containing air pollutants, through rainwater sampling and laboratory experiments. The pollen grain counts, pollen burst ratios, ionic concentrations and pH in each rainwater sample were measured, when rainwater samples were separately collected in Saitama City, a suburban area north of Tokyo metropolis. Additionally, three simulated rainwater (SR) samples were prepared to investigate the releasing behaviour of pollen allergenic species. In the samplings, the most pollen grains were trapped into initial rainwater (IR). Moreover, burst pollen grains were observed in many rainwater samples. Burst ratio of pollen grains were positively correlated with pH and ionic concentrations in rainwater. Therefore, it was thought that pollen grains were washed out by IR containing air pollutants. On the other hand, for the laboratory experiments, the elution of allergenic Cry j 1 and Cry j 2 was observed when pollen grains were exposed to different SR samples. A time-dependent increase of Cry j 1 was observed, but the elution of Cry j 2 was not observed from pollen grains exposed to SR samples. In particular, the elution of Cry j 1 increased by contact with SR samples under conditions of Asian dust events. The results demonstrated that the burst of pollen grains is associated with the production of fiparticles containing pollen allergenic species, and that the release of allergenic species was induced by rainwater containing air pollutants.

Magnetic, geochemical characterization and health risk assessment of road dust in Xuanwei and Fuyuan, China

As an accumulation of solid organic and inorganic pollutant particles on outdoor ground surfaces, road dust is an important carrier of heavy metal contaminants and can be a valuable medium for characterizing urban environmental quality. Because the dusts can be an important source of atmospheric particles and take impact on human health, the aim of this study described in detail the mineralogical characteristics, morphology, and heavy metal content of road dust from Xuanwei and Fuyuan, locations with high lung cancer incidence. Our results show that the average concentrations of heavy metals in road dust were higher than their background values. Higher concentrations of heavy metals were found in the magnetic fractions (MFs) than in the non-magnetic fractions (NMFs). Magnetic measurements revealed high magnetic susceptibility values in the road dust samples, and the dominant magnetic carrier was magnetite. The magnetic grains were predominantly pseudo-single domain, multi-domain, and coarse-grained stable single domains (coarse SSD) in size. SEM/XRD analysis identified two groups of magnetic particles: spherules and angular/aggregate particles. Hazard index (HI) values for adults exposure to road dust samples, including MF, Bulk, and NMF, in both areas were lower or close to safe levels, while HI values for childhood exposure to magnetic fractions in both areas were very close or higher than safe levels. Cancer risks from road dust exposure in both areas were in the acceptable value range.

Reduction of fine particles exhausted from small-size combustor using agricultural waste residue by controlling burning temperatures

About 3.9 million tons of agricultural residue waste biomass such as rice husk and straw are stably produced from rice each year in Japan. It is reported that vapor pollutants and particles emitted from the burning of agricultural residue waste biomass such as waste rice husk and straw have serious infl uences on visibility, human health, and global climate. Therefore, it is necessary to utilize waste rice husk and straw effectively to reduce air pollution. In recent years, there has been an increasing demand for the effective utilization of waste agricultural residue biomass instead of fossil fuel in combustors for farming such as greenhouses heating during the winter season. However, there is a lack of regulations or laws to control air pollution from these small-size combustors in Japan. So far, small-size combustors have been characterized by their structural simplicity and low cost. Therefore, it is necessary to evaluate and control the emission of air pollutants such as fiparticles (i.e. PM 2.5 ‐ particles below 2.5 µm in aerodynamic diameter) due to the poor combustion performance of small-size combustors. In this study, it was investigated whether it would be possible to utilize biomass fuel selected from waste rice husk and straw of agricultural residue waste biomass based on the laboratory combustion experiments. The emission behavior of harmful suspended particulate matter produced from burning rice husk and straw was evaluated by measuring carbonaceous and ionic composition of PM 2.5 in the exhaust gases. From the analytical results, it was found that particulate mass concentrations reduced substantially at high-temperature combustion. However, ionic compositions were increased with the increase in combustion temperature. It can be suggested that stable combustion should be performed under suitable conditions to control air pollutants emitted from biomass fuel, although small-size combustors are still not regulated to control PM 2.5 emission.

Allergenicity of recombinant Humulus japonicus pollen allergen 1 after combined exposure to ozone and nitrogen dioxide

Ozone (O3) and nitrogen dioxide (NO2) are thought to play primary roles in aggravating air pollution-induced health problems. However, the effects of joint O3/NO2 on the allergenicity of pollen allergens are unclear. Humulus japonicus pollen allergen 1 (Hum j1) is a profilin protein that causes widespread pollinosis in eastern Asia. In order to study the effects of combined O3/NO2 on the allergenicity of Hum j1, tandem six-histidine peptide tag (His6)-fused recombinant Hum j1 (rHum j1) was expressed in a prokaryotic system and purified through His6 affinity chromatography. The purified rHum j1 was used to immunize SD rats. Rat sera with high titers of IgG and IgE antibodies against rHum j1 were used for allergenicity quantification. The rHum j1 was exposed to O3/NO2, and changes in allergenicity of the exposed rHum j1 were assayed using the immunized rat antibodies. Tandem LC-MS/LC (liquid chromatography-mass spectrometer/liquid chromatography spectrometer) chromatography and UV and circular dichroism (CD) spectroscopy were used to study the structural changes in rHum j1. Our data demonstrated that a novel disulfide bond between the sulfhydryl groups of two neighboring cysteine molecules was formed after the rHum j1 exposure to joint O3/NO2, and therefore IgE-binding affinity was increased and the allergenicity was reinforced. Our results provided clues to elucidate the mechanism behind air pollution-induced increase in pollinosis prevalence.

Atmospheric HULIS and its ability to mediate the reactive oxygen species (ROS): A review

Atmospheric humic-like substances (HULIS) are not only an unresolved mixture of macro-organic compounds but also powerful chelating agents in atmospheric particulate matters (PMs); impacting on both the properties of aerosol particles and health effects by generating reactive oxygen species (ROS). Currently, the interests of HULIS are intensively shifting to the investigations of HULIS-metal synergic effects and kinetics modeling studies, as well as the development of HULIS quantification, findings of possible HULIS sources and generation of ROS from HULIS. In light of HULIS studies, we comprehensively review the current knowledge of isolation and physicochemical characterization of HULIS from atmospheric samples as well as HULIS properties (hygroscopic, surface activity, and colloidal) and possible sources of HULIS. This review mainly highlights the generation of reactive oxygen species (ROS) from PMs, HULIS and transition metals, especially iron. This review also summarized the mechanism of iron-organic complexation and recent findings of OH formation from HULIS-metal complexes. This review will be helpful to carry out the modeling studies that concern with HULIS-transition metals and for further studies in the generation of ROS from HULIS-metal complexes.