The bioreactivity of the sub-10 μm component of volcanic ash: Soufrière Hills volcano, Montserrat

With the recent eruption of the Icelandic volcano Eyafallajökull and resulting ash cloud over much of Europe there was considerable concern about possible respiratory hazards. Volcanic ash can contain minerals that are known human respiratory health hazards such as cristobalite. Short-term ash exposures can cause skin sores, respiratory and ocular irritations and exacerbation of pre-existing lung conditions such as asthma. Long-term occupational level exposures to crystalline silicon dioxide can cause lung inflammation, oedema, fibrosis and cancer. The potential health effects would be dependent on factors including mineralogy, surface chemistry, size, and levels and duration of exposure. Bulk ash from the Soufrière Hills volcano was sourced and inhalable (<2.5μm) ash samples prepared and physicochemically characterised. The fine ash samples were tested for bioreactivity by SDS-PAGE which determined the strength of binding between mineral grains and lung proteins. Selected proteins bound tightly to cristobalite, and bound loosely to other ash components. A positive correlation was seen between the amount of SiO2 in the sample and the strength of the binding. The strength of binding is a function of the mineral’s bioreactivity, and therefore, a potential geo-biomarker of respiratory risk

Testing particulate matter toxicity via in vitro methods: What should be tested?

Unlike other toxic substances, usually of a known chemical formula, air particulate matter (PM) is a mixture of solid and liquid particles. The most frequently used tests are in vitro in nature and examine ‘cell viability’ following 24-hour exposure to PM. In most cases, PM induces sub-toxic viability responses but other key cell functions are not detected. The aim of this study was to compare the toxicity profiles of engineered NPs: zinc oxide (ZnO), crystalline form of silicon oxide (SiO2), and nickel (Ni), which are frequently present in ambient air pollution. Three different assays (acellular and cellular) were chosen to test PM biological targets: (1) plasmid scission assay – detecting DNA damage (indicative of the ability to produce reactive oxygen species; ROS; Figure 1); (2) haemolysis assay – informing about red blood cells (RBCs) membranes integrity; (3) proliferation assay inspected on HUVEC (human umbilical vein endothelial cells) at 24, 48 and 72 hours post-exposure to NPs

Combustion particles emitted during church services: Implications for human respiratory health

Burning candles and incense generate particulate matter (PM) that produces poor indoor air quality and may cause human pulmonary problems. This study physically characterised combustion particles collected in a church during services. In addition, the emissions from five types of candles and two types of incense were investigated using a combustion chamber. The plasmid scission assay was used to determine the oxidative capacities of these church particles. The corresponding risk factor (CRf) was derived from the emission factor (Ef) and the oxidative DNA damage, and used to evaluate the relative respiratory exposure risks. Real-time PM measurements in the church during candle–incense burning services showed that the levels (91.6 μg/m3 for PM10; 38.9 μg/m3 for PM2.5) exceeded the European Union (EU) air quality guidelines. The combustion chamber testing, using the same environmental conditions, showed that the incense Ef for both PM10 (490.6– 587.9 mg/g) and PM2.5 (290.1–417.2 mg/g) exceeded that of candles; particularly the PM2.5 emissions. These CRf results suggested that the exposure to significant amounts of incense PM could result in a higher risk of oxidative DNA adducts (27.4–32.8 times) than tobacco PM. The generation and subsequent inhalation of PM during church activities may therefore pose significant risks in terms of respiratory health effects

The internal microstructure and fibrous mineralogy of fly-ash from coal-burning power stations

Coal fly-ash (CFA) is a significant environmental pollutant that presents a respiratory hazard when airborne. Although previous studies have identified the mineral components of CFA, there is a paucity of information on the structural habits of these minerals. Samples from UK, Polish and Chinese power stations were studied to further our understanding of the factors that affect CFA geochemistry and mineralogy. ICP-MS, FE-SEM/EDX, XRD, and laser diffraction were used to study physicochemical characteristics. Analysis revealed important differences in the elemental compositions and particle size distributions of samples between sites. Microscopy of HF acid-etched CFA revealed the mullite present possesses a fibrous habit; fibres ranged in length between 1–10μm. Respirable particles (<10μm) were frequently observed to contain fibrous mullite. We propose that the biopersistence of these refractory fibres in the lung environment could be contributing towards chronic lung diseases seen in communities and individuals continually exposed to high levels of CFA

The respiratory toxicity of coal fly ash

The combustion of coal for the generation of electricity has many environmental implications. Coal fly ash (CFA; Figure 1) is a product of coal combustion, formed from the incombustible mineral matter contained within the coal. CFA is respirable (i.e. <2.5μm diameter) and known to be detrimental to human respiratory health upon exposure (Brown, 2011). The aim of this study was to compare the relative respiratory toxicity of CFA samples obtained from three Chinese coal-burning power stations to CFA obtained from a UK coal-burning power station; both bulk and respirable PM10 samples were tested. In order to elucidate CFA toxicity, a multi-disciplinary approach was taken, thereby considering geochemical aspects of the fly ash as well as biochemical properties

The respiratory toxicity of coal fly ash

The combustion of coal for the generation of electricity has many environmental implications. Coal fly ash (CFA; Figure 1) is a product of coal combustion, formed from the incombustible mineral matter contained within the coal. CFA is respirable (i.e. <2.5μm diameter) and known to be detrimental to human respiratory health upon exposure (Brown, 2011). The aim of this study was to compare the relative respiratory toxicity of CFA samples obtained from three Chinese coal-burning power stations to CFA obtained from a UK coal-burning power station; both bulk and respirable PM10 samples were tested. In order to elucidate CFA toxicity, a multi-disciplinary approach was taken, thereby considering geochemical aspects of the fly ash as well as biochemical properties