As a result of a tragic industrial accident, a highly alkaline red mud sludge inundated settlements and agricultural areas near Ajka, Hungary on October 4, 2010. One of the major concerns about the aftermaths of the accident is the potential health effects of vast amounts of fugitive dust from red mud sediment. Thus, we studied the chemical and physical properties of particles of red mud and its respirable fugitive dust, and performed toxicity measurements. Under unfavorable meteorological conditions dry red mud sediment could emit very high amounts of respirable alkaline particles into the air. The number size distribution of fugitive dust peaks above 1 μm aerodynamic diameter; therefore, its inhalation is unlikely to affect the deep regions of the lungs. No significant mineralogical or elemental fractionation was observed between the sediment and dust, with the major minerals being hematite, cancrinite, calcite, and hydrogarnet. Although the high resuspension potential and alkalinity might pose some problems such as the irritation of the upper respiratory tract and eyes, based on its size distribution and composition red mud dust appears to be less hazardous to human health than urban particulate matter.

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Abstract. In addition to its mass concentration, the health effects of urban particulate matter may depend on its particle size distribution and chemical composition. Yet air pollution regulations rely on exclusively bulk PM 10 concentration measurements, without regard to their potentially different health effects under different conditions. Aerosols from various sources are well known to contain a plethora of toxic, carcinogenic, mutagenic or teratogenic constituents such as heavy metals and polycyclic aromatic hydrocarbons. Extensive public health studies established the link between mass concentrations of PM 2.5 / PM 10 and health problems within the population. However, little is known about the relative importance of PM from different sources and the effect of seasonality on the toxicity. Here we present the application of a simple and sensitive method for the direct assessment of the overall ecotoxicity of various PM 2.5 / PM 10 samples collected on filters. The method is based on the Vibrio fischeri bioluminescence inhibition bioassay that has been standardized for solid samples, representing a relevant biological exposure route. Direct emission samples proved to be significantly more ecotoxic than photochemically processed aerosol, thus marked differences were observed between the ecotoxicities of urban PM 10 in summer and winter. These effects of urban PM 10 may be useful supplementary indicators besides the mass concentrations of PM 2.5 / PM 10 in cities.

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Diesel exhaust is one of the major sources of fine and ultra-fine particulate matter in urban air. Toxicity of diesel-powered engine emissions has been quite widely assessed; however, much less information is available on their ecotoxicity. In our study, the kinetic version of the Vibrio fischeri bioluminescence inhibition bioassay based on the ISO 21338:2010 standard was used to characterise the ecotoxicity of diesel-powered buses. It is a direct contact test in which solid samples are tested in suspension and test organisms are in direct contact with toxic particles. The age of the selected buses fell into a wide range; the oldest one was produced in 1987. Diesel engines of different emission standards (Euro0-Euro4) were included. Measured EC50 values of Euro0-Euro1 engine emissions fell into the same range, 1.24-0.96 μg ml(-1), respectively. On the contrary, emission of Euro4 vehicle proved to be non-toxic. Genotoxic potential of the samples was also estimated, using the colorimetric SOS-chromotest™. Genotoxicity was detected also for Euro0 and Euro1 buses, showing correlation with the ecotoxic potential. The fact that the particulates from Euro4 vehicles did not show ecotoxic/genotoxic effect implies that replacing old Euro1 and Euro2 buses can be a highly effective solution for reducing environmental hazard of automotive emissions. The whole-aerosol testing method is a cheap alternative that can be used in engine developments and emission control.

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Extended research has been carried out on the antimicrobial properties of herbs belonging to the family Asteraceae, trying to establish their potential use in natural pest control, in addition to human medicinal applications. For testing and quantifying antibacterial activity, most often standard microbial protocols are used. In this study the aggregate bactericide effect of four species (Artemisia absinthium L., A. vulgaris L., Chrysanthemum leucanthemum L. and Achillea millefolium L.) was screened using the Vibrio fischeri bioluminescence inhibition bioassay. The two Artemisia species which have well-established use as antibacterial, exerted the highest toxicity. Toxicity of Chrysanthemum leucanthemum fell into the same range, although this herb has restricted use in human medicine. On the contrary, Achillea millefolium, which is widely recommended against inflammations, showed significantly lower toxicity.