Characterization of cytotoxicity of airborne particulates from urban areas of Lahore

In vitro toxicity of particulate matter emissions from residential pellet combustion

Particulate matter emissions (PM₁₀) from the combustion, in a residential stove, of two commercial brands of certified (ENplus A1) pellets, a non-certified brand and laboratory made pellets of acacia were tested for their ability to induce ecotoxic, cytotoxic, and mutagenic responses in unicellular organisms and a human cell line. Ecotoxicity was evaluated through the Vibrio fischeri bioluminescence inhibition assay. Moreover, cytotoxicity was assessed at two time points (24- and 48-hr) through two complementary techniques in order to evaluate the cellular metabolic activity and membrane integrity of human lung epithelial cells A549. The Ames test using two Salmonella typhimurium strains (TA100 and TA98) was employed to assess the mutagenic potential of the polycyclic aromatic hydrocarbon fraction extracted from the PM₁₀ samples. Results obtained with the bioluminescent bacteria indicated that only particles from the combustion of acacia pellets were toxic. All samples induced impairment on the A549 cells metabolic activity, while no significant release of lactate dehydrogenase was recorded. PM₁₀ emissions from acacia pellets were the most cytotoxic, while samples from both certified pellets evoked significant cytotoxicity at lower doses. Cytotoxicity time-dependency was only observed for PM₁₀ from the combustion of acacia pellets and one of the brands of certified pellets. Mutagenic activity was not detected in both S. typhimurium strains. This study emphasises the role of the raw material for pellet manufacturing on the toxicological profile of PM emissions. Alternative raw materials should be deeply investigated before their use in pelletisation and combustion in residential appliances.

Characterization of ambient PM1 at a suburban site of Agra: chemical composition, sources, health risk and potential cytotoxicity

The present study was conducted at a University campus of Agra to determine concentrations of crustal and trace elements in submicron mode (PM₁) particles to reveal sources and detrimental effects of PM₁-bound metals (Cr, Cd, Mn, Zn, As, Co, Pb, Cu and Ni) in samples collected in the foggy (1 December 2016-17 January 2017) and non-foggy periods (1 April 2016-30 June 2016). Samples were collected twice a week on preweighed quartz fibre filters (QM-A 47 mm) for 24 h using Envirotech APM 577 (flow rate 10 l min^-1). Mass concentration of PM₁ was 135.0 ± 28.2 and 54.0 ± 18.5 µg/m³ during foggy and non-foggy period, respectively; crustal and trace elements were 13 and 4% during foggy and 11 and 3% in the non-foggy period. Source identification by PCA (principal component analysis) suggested that biomass burning and coal combustion was the prominent sources in foggy period followed by resuspended soil dust, industrial and vehicular emission, whereas in non-foggy period resuspended soil dust was dominant followed by biomass burning and coal combustion, industrial and vehicular emissions. In both episodes, Mn has the highest Hq (hazard quotient) value and Cr has the highest IlcR (Incremental Lifetime Cancer Risk) value for both adults and children. In vitro cytotoxicity impact on macrophage (J774) cells was also tested using MTT assay which revealed decreasing cell viability with increasing particle mass.

Evaluation of waterpipe smoke toxicity in C57BL/6 mice model

Waterpipe smoking is a popular pastime worldwide with statistics pointing to an alarming increase in consumption. In the current paper, the evaluation of sub-chronic waterpipe smoke exposure was undertaken using C57BL/6 female mice using a dynamic exposure setting to emulate smoke exposure. Mice were daily subjected to either one (single exposure, SE) or two sessions (double exposure, DE) of waterpipe-generated smoke (two-apple flavor) for a period of two months. Although lungs histopathological examination pointed to a minor inflammation in smoke-exposed mice compared to control air-exposed (CON) group, the lung weights of the waterpipe-exposed mice were significantly higher (+72% in SE and +39% in DE) (p < 0.01) when compared to CON group. Moreover, changes in the protein expression of several proteins such as iNOS and JNK were noted in the lungs of smoke-exposed mice. However, no changes in p38 and EGFR protein levels were noted between the three groups of mice. Our results mainly showed a significant increase in urea serum levels (+28%) in SE mice along with renal pathological damage in both SE and DE mice compared to CON. Additionally, severe significant DNA damages (p < 0.05) were reported in the lungs, kidneys, bone marrow and liver of waterpipe-exposed animals, using MTS and COMET assays. These findings highlighted the significant risks posed by sub-chronic waterpipe smoke exposure in the selected animal model and the pressing need for future better management of waterpipe indoor consumption.

The effects of autophagy on vascular endothelial cells induced by airborne PM2.5

The purpose of this study was to examine the direct toxicity of PM2.5 collected from Beijing on human umbilical vein endothelial cells (HUVEC). A Cell Counting Kit 8 (CCK8) assay demonstrated that PM2.5 exposure decreased the proliferation of HUVECs in a dose-dependent manner. We also found that PM2.5 exposure induced autophagy in HUVECs, as evidenced by: (1) an increased number of double-membrane vesicles; (2) enhanced conversion and punctuation of the microtubule-associated protein light chain 3 (LC3); and (3) decreased levels of the selective autophagy substrate p62 in a time-dependent manner. Furthermore, promoting autophagy in PM2.5-exposed HUVECs with rapamycin increased the cell survival rate, whereas inhibiting autophagy via 3-methyladenine significantly decreased cell survival. These results demonstrate that PM2.5 exposure can induce cytotoxicity and autophagy in HUVECs and that autophagy play a protective role against PM2.5-induced cytotoxicity. The findings of the present study imply a direct toxic effect of PM2.5 on HUVECs and provide novel insight into the mechanism of cardiovascular diseases caused by PM2.5 exposure.

Role of metals in free radical generation and genotoxicity induced by airborne particulate matter (PM2.5) from Pune (India)

In the present study, metal-facilitated free radical generation in particulate matter (PM) and its association with deoxyribonucleic acid (DNA) damage were studied. The examined data showed that the concentration of fine PM in Pune exhibited seasonal variations. Inductively coupled plasma-atomic emission spectrometry (ICP-AES) was used to examine the metal composition, which showed the presence of metals such as Cu, Zn, Mn, Fe, Co, Cr, Pb, Cd, and Ni. Fe metal was present in the highest concentrations in both the seasons, followed by Zn. The scanning electron microscopy-energy-dispersive spectrometer (SEM-EDS) results also demonstrated that the fine PM particles deposited in summer samples were less than those of winter samples, suggesting that the PM load in winter was higher as compared to that in summer. Elemental mapping of these particles substantiates deposition of metals as Fe, Zn, etc. on particles. The electron paramagnetic species (EPR) technique was utilized for free radical detection, and plasmid DNA assay was utilized to study the genotoxicity of ambient fine PM. Obtained g values show the presence of radicals in PM samples of Pune. PM contains the C-centered radical with a vicinal oxygen atom (g = 2.003). In addition to this, the g value for Fe was also observed. Therefore, we intend that the radicals related with fine PM comprise metal-mediated radicals and produce DNA damage. The plasmid DNA assay results indicated that the TM₅₀ values (toxic mass of PM causing 50 % of plasmid DNA damage) of PM exhibited seasonal variations with higher TM₅₀ values for summer and lower TM₅₀ values during winter.

Characterization and Cytotoxicity of PM<0.2, PM0.2-2.5 and PM2.5-10 around MSWI in Shanghai, China

BACKGROUND

The potential impact of municipal solid waste incineration (MSWI), which is an anthropogenic source of aerosol emissions, is of great public health concern. This study investigated the characterization and cytotoxic effects of ambient ultrafine particles (PM<0.2), fine particles (PM0.2-2.5) and coarse particles (PM2.5-10) collected around a municipal solid waste incineration (MSWI) plant in the Pudong district of Shanghai.

METHODS

Mass concentrations of trace elements in particulate matter (PM) samples were determined using ICP-MS (Inductively Coupled Plasma Mass Spectrometry). The cytotoxicity of sampled atmospheric PM was evaluated by cell viability and reactive oxygen species (ROS) levels in A549 cells.

RESULT

The mass percentage of PM0.2-2.5 accounted for 72.91% of the total mass of PM. Crustal metals (Mg, Al, and Ti) were abundant in the coarse particles, while the anthropogenic elements (V, Ni, Cu, Zn, Cd, and Pb) were dominant in the fine particles. The enrichment factors of Zn, Cd and Pb in the fine and ultrafine particles were extremely high (>100). The cytotoxicity of the size-resolved particles was in the order of coarse particles < fine particles < ultrafine particles.

CONCLUSIONS

Fine particles dominated the MSWI ambient particles. Emissions from the MSWI could bring contamination of anthropogenic elements (Zn, Cd and Pb) into ambient environment. The PM around the MSWI plant displayed an additive toxic effect, and the ultrafine and fine particles possessed higher biological toxicity than the coarse particles.