Nóra Kováts

The Red Mud Accident in Ajka (Hungary): Characterization and Potential Health Effects of Fugitive Dust

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.

The ecotoxicological evaluation of Cylindrospermopsis raciborskii from Lake Balaton (Hungary) employing a battery of bioassays and chemical screening

Ecotoxicity of four Cylindrospermopsis raciborskii strains (ACT 9502, ACT 9503, ACT 9504, ACT 9505) isolated from Lake Balaton (Hungary) was evaluated in four aquatic bioassays including the Thamnocephalus platyurus acute lethality test; Daphnia magna acute immobilization assay; D. magna feeding inhibition assay and Danio rerio embryo developmental toxicity assay, assisted by chemical screening for known toxins by HPLC-MS. For reference, we analyzed in parallel the toxin content and toxic effects of two previously characterized toxin-producing strains: the Australian cylindrospermopsin producer AQS C. raciborskii and the anatoxins producer Oscillatoria sp. PCC 6506. Bioassays were used to evaluate the overall toxicity of the hydrophilic bioactive metabolites pool synthesized by the selected cyanobacteria. Chemical screening has proven that the ACT C. raciborskii extracts investigated did not contained cylindrospermopsins and anatoxins. The relative toxicity of the ACT C. raciborskii aqueous extracts observed in each bioassay was comparable to the effects recorded for the anatoxins producer PCC 6506 strain while toxicity values (EC50/LC50) calculated for the AQS extract were in general one order of magnitude lower. Concerning sublethal effects of ACT C. raciborskii extracts to the D. rerio embryogenesis, the general morphological abnormality observed was a significant retardation of development. Overall, our results suggest that C. raciborskii populating Lake Balaton produce metabolites with significant bioactive potencies. Therefore, continued investigation of these unknown compounds is required.

Evaluation of some alternative guidelines for risk assessment of various habitats.

Recently, some relatively inexpensive and simple methods suitable for classification of dangerous wastes and pollution of surface water have been developed. In order to compare the performance of the various alternative bioassays a series of examinations have been carried out with Thamnotox kits and Daphnia heart test. In addition, duckweed, as a relatively new bioindicator has been used. The alternative methods have been used for the monitoring of river Tisza, and for detection of the pollution of some watersheds. The results revealed that the alternative tests are sensitive to indicate the combined effect of various pollutants in aquatic ecosystems. It seems to be that the tests using crustacean species would give realistic results in well-defined point sources, but they can be accepted somewhat more sceptic way when comparing samples taken from different habitats. Daphnia heart rate were specific only to a limited number of compounds like pyrethroid type pesticides. For some mixtures of pollutants there was a correlation between Thamnotox and Daphnia heart data. In the case of Lemna minor at some sites instead of growth inhibition a stimulation can be detected. The toxicity estimation with Lemna strains will give us a habitat-specific indication of the pollution. An important conclusion of the results is that there is no universal bioassay available for detection of all types of pollution. The best results can be obtained with employment of a battery of bioassays.

Ecotoxicological characterisation of exhaust particulates from diesel-powered light-duty vehicles

AbstractDiesel exhaust is one of the major sources of fine and ultrafine 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 cars. The method is sensitive enough to test the ecotoxic effect of the emission of individual vehicles. In general, significant positive correlation was found between ecotoxicity (expressed as Toxic Unit /TU/values) and total carbon (TC) as well as between TU and polycyclic aromatic hydrocarbon (PAH) concentrations.

Assessment of the genotoxic potential of Hoechst 33342, SYBR-14 and PI using the SOS ChromoTest™

Abstract Fluorochromes in combination with flow cytometry can be used for laboratory assessment of semen quality in humans and domestic animals. Some studies have reported the potential toxicity of these fluorochromes toward the cells analyzed, but not toward the laboratory technician who operates the analytical instrument. We tested the genotoxic potential of three fluorochromes, SYBR-14, propidium iodide, and Hoechst 33342, using the colorimetric SOS ChromoTest™. The test revealed no genotoxic potential for any of the three fluorochromes within the dilution ranges investigated. We conclude that occasional direct contact with these fluorescent probes does not necessarily pose a genotoxic hazard.

Ecotoxicological characterisation of sedimentation in the Kis-Balaton Water Protection System.

The main function of the Kis-Balaton Water Protection System is to retain nutrients and total suspended solids, thus protecting the water quality of Lake Balaton. In this paper, the toxic nature of the sediment in the 2nd reservoir of the KBWPS has been characterised, using a battery of tests: Vibrio fischeri acute bioassay on whole sediment samples, and V. fischeri bioassay on pore water and elutriate samples. The latest version of the V. fischeri bioluminescence inhibition was applied, the Flash assay which uses a kinetic mode and is able to detect the toxicity of solid, turbid/coloured samples. Whole sediment toxicity showed a clear spatial distribution of toxicity, in parallel with elutriate toxicity. However, no pore water toxicity was detected, leading to the conclusion that contaminants are not water soluble.

Comparative Assessment of the Mussel Micronucleus Test Versus Bacterial Bioassays for Genotoxicity Testing of Benzo[a]pyrene

Polycyclic aromatic hydrocarbons are hazardous compounds to the environment and human health, thus their detection is an important task. In this study the genotoxic effect of benzo[a]pyrene (B[a]P) was examined on a freshwater mussel Unio pictorum and results were compared to bacterial tests, such as the Ames test and SOS chromotest. The aim of the study was to calibrate the sensitivity of the mussel micronucleus test to that of the two bacterial tests using B[a]P as a reference chemical. The Ames and the micronucleus tests gave similar response both in sensitivity and in concentrationresponse pattern. These two tests are proposed to be applied in a battery for genotoxicity testing.

Genotoxic effect of Lythrum salicaria extract determined by the mussel micronucleus test.

A wide range of aquatic plants have been proven to release allelochemicals, of them phenolics and tannin are considered rather widely distributed. Tannins, however, have been demonstrated to have genotoxic capacity. In our study genotoxic potential of Lythrum salicaria L. (Purple Loosestrife, family Lythraceae) was assessed by the mussel micronucleus test, using Unio pictorum. In parallel, total and hydrolysable tannin contents were determined. Results clearly show that the extract had a high hydrolysable tannin content and significant mutagenic effect. As L. salicaria has been long used in traditional medicine for chronic diarrhoea, dysentery, leucorrhoea and blood-spitting, genotoxic potential of the plant should be evaluated not only with regard to potential effects in the aquatic ecosystem, but also assessing its safe use as a medicinal herb.

Quantifying of bactericide properties of medicinal plants

Extended research has been carried out to clarify the ecological role of plant secondary metabolites (SMs). Although their primary ecological function is self-defence, bioactive compounds have long been used in alternative medicine or in biological control of pests. Several members of the family Labiatae are known to have strong antimicrobial capacity. For testing and quantifying antibacterial activity, most often standard microbial protocols are used, assessing inhibitory activity on a selected strain. In this study the applicability of a microbial ecotoxtest was evaluated to quantify the aggregate bactericide capacity of Labiatae species, based on the bioluminescence inhibition of the bacterium Vibrio fischeri. Striking differences were found amongst herbs, reaching even 10-fold toxicity. Glechoma hederacea L. proved to be the most toxic, with the EC50 of 0.4073 g dried plant/l. LC50 values generated by the standard bioassay seem to be a good indicator of the bactericide property of herbs. Traditional use of the selected herbs shows a good correlation with bioactivity expressed as bioluminescence inhibition, leading to the conclusion that the Vibrio fischeri bioassay can be a good indicator of the overall antibacterial capacity of herbs, at least on a screening level.

Novel Daphnia Test For Detecting Chemical Pollution

Daphnia magna (water flea) is perhaps the most commonly used test organism. As they represent primary consumers in freshwater aquatic ecosystems, their relevance in screening bioassays is very high. However, performing the standard Daphnia mortality test requires a 24–48 h exposure time, therefore no rapid response can be acquired on the risk posed by any environmental contamination. A novel bioassay has been elaborated and tested in our laboratory, using the above mentioned Daphnia species, but based on another ecological effect, the inhibition of feeding activity. Applicability and sensitivity of the test was assessed using potassium dichromate. Standard Daphnia test was also carried out as reference. The sensitivity range of the new method was similar to the reference test (EC50 was in the same magnitude in comparison to Daphnia magna mortality test). Its further benefit is that this bioassay is using a sublethal endpoint.