Milka Vidović

Freshwater Cyanobacterial Blooms and Primary Liver Cancer Epidemiological Studies in Serbia

A large part of Central Serbia experiences continual shortage of sufficient ground water resources. For that reason, more than 20 reservoirs serve as drinking water suppliers. Significant and persistent cyanobacterial “blooms” have been recognized in nine of them. Samples for cyanotoxin analyses were taken during and after “blooms” in Ćelije Reservoir and from Kruševac town-supplied tap water from that reservoir two days later. Concentration of microcystin-LR was 650 μ gL–1 in the reservoir, while the tap water contained 2.5 μ gL–1. In the two investigated periods, the high primary liver cancer (PLC) mortality of 11.6 from 1980–1990 and extremely high PLC incidence of 34.7 from 2000–2002 were observed in the regions affected by heavy cyanobacterial “blooms.” In contrast, PLC mortality and incidence rates were substantially lower in the regions not affected by cyanobacterial blooms: in 1980–1990 the rate of PLC mortality amounted to 2.7 in Kosovo, 7.6 in Vojvodina, and 8.3 in the non-affected regions of Central Serbia; while in 2000–2002 PLC incidence amounted to 4.1 in Kosovo, 5.2 in Vojvodina, and 13.6 in the non- or less-affected regions of Central Serbia. Keeping in mind that the most affected PLC regions in Central Serbia (Toplički, Niški, and Šumadijski regions) have the water supply systems based on six reservoirs found regularly in bloom during summer months and that some of the regions are also connected with two boundary “blooming” reservoirs, representing a total of eight of nine blooming reservoirs, it is easy to presume that the PLC incidence could be related to drinking water quality. The uneven geographic distribution of liver cancer in Serbia is conspicuous and hot spots could be related to drinking water supply. It is very clear that the high-risk regions for PLC occurrence correspond with drinking water reservoirs continually found with cyanobacterial blooms, and the low risk regions correspond with water supplies not affected by cyanobacteria.

Cyanotoxins: Characteristics, production and degradation routes in drinking water treatment with reference to the situation in Serbia

Cyanobacteria are members of phytoplankton of the surface freshwaters. The accelerated eutrophication of freshwaters, especially reservoirs for drinking water, by human activity has increased the occurrence and intensity of cyanobacterial blooms. They are of concern due to their ability to produce taste and odors compounds, a wide range of toxins, which have a hepatotoxic, neurotoxic, cytotoxic and dermatotoxic behavior, being dangerous to animal and human health. Therefore, the removal of cyanobacteria, without cell lysis, and releasing of intracellular metabolites, would significantly reduce the concentration of these metabolites in the finished drinking water, as a specific aim of the water treatment processes. This review summarizes the existing data on characteristics of the cyanotoxins, their productions in environment and effective treatment processes to remove these toxins from drinking water.

Epidemiology of Primary Liver Cancer in Serbia and Possible Connection With Cyanobacterial Blooms

Today, the occurrence of harmful cyanobacterial blooms is a common phenomenon and a potential global health problem. Cyanobacteria can produce metabolites highly toxic to humans. More than 80% of reservoirs used for water supply in Central Serbia have bloomed over the past 80 years. A 10-year epidemiological study showed a significant increase in the incidence of primary liver cancer (PLC) in the regions where water from the blooming reservoirs was used for human consumption. At the same time, no correlation was found between the incidence of PLC and other risk factors, such as cirrhosis and hepatitis viruses. Given the strong association with PLC induction and various known possible mechanisms of carcinogenic action, it is highly possible that, cyanotoxins—acting as initiator and promoter—may be the major risk factor that acts synergistically with other risk factors to cause increased incidence of PLC. However, at present, it is still not certain whether cyanotoxins alone were sufficient to induce PLC. Therefore, additional assessment of the health risks that may arise from human exposure to cyanotoxins is advisable.

Analysis of Tea for Metals by Flame and Graphite Furnace Atomic Absorption Spectrometry with Multivariate Analysis

ABSTRACT The concentrations of iron, zinc, manganese, copper, chromium, nickel, lead, arsenic, and cadmium were determined using flame and graphite furnace atomic absorption spectrometry in nine herbal tea samples. Hawthorn, yarrow, elderflower, and bearberry are herbal teas for which the metal content has been rarely determined. The concentration of cadmium in St John’s wort exceeded the maximum permissible limit of 0.3 mg/kg. The metals were also determined in aqueous extracts following 5, 10, and 20 min of boiling and using different preparations, including acidification with lemon juice. The influence of these factors on metal release was demonstrated using multivariate analyses by redundancy analysis and principal component analysis. The metal release was not considerably affected by the boiling time, while the acidity of the medium was generally positively correlated. For the infusions, arsenic was detected only in acidified mint tea. The extraction efficiencies of metals were determined and classified as highly, moderately, and poorly extractable, with chromium showing largest variations.

Geochemical mapping of riverbank profiles in the basin area of the river Ibar: Role in establishing the geochemical basis for the assessment of anthropogenic influence on the environment

Geochemical mapping of riverbank profiles of the basin area of the river Ibar was performed in the purpose of making regional geochemical map of Serbia 1:1000000. In this area, deposits of lead and zinc are located, and they are characterized by very complex geological composition. Sampling net at chosen locations of riverbank profiles was adjusted to the morphological and hydrographic characteristics of the terrain. At every profile, samples were collected from A-horizon, Ob-overbank sediment and S-active stream sediment, while tracking the changes of lithological members, in accordance to the WEGS methodology (Western European Geological Surveys). The preserved geochemical track in the overbank sediment is of special significance for correlation the results of chemical elements in the surface part of (A-horizon) and active contemporary stream sediment. In the analytical process, beside determining contents of Pb, Zn, Cu, Co, Ni, Cr, Sb, V, Cd and other elements, the radiometric examinations of contents of U 238 , Th 232 and K 40 , were also conducted as well as the appropriate sedimentological analyses. On the basis of geochemical prospection results, a data base was formed which represents a foundation for estimation of anthropogenic influence on the living environment of rural settlements in the basin area of the river Ibar. In accordance to the geological-structural and morphological characteristics of the terrain, the results are applicable in the research of mineral raw materials, in agriculture, forestry, geomedicine, etc.

Hydrogeochemical investigation of ground and surface water in the Neogene - Quaternary sediments

Geochemical investigations in order to identify the mineral deposits, as well as the sources of water supply of rural settlements included in the area of Bela Crkva, between the Nera and the Karas rivers, draining the Neogene and Quaternary sediments. During the prospecting, water samples were collected from surface water streams, springs, wells, drills, water reservoirs, as well as the samples of stream sediments and rocks. Hydrogeochemical investigations are of significance, where, in the water of Vrsac hills, elevated levels of radionuclides U, Ra and Rn, and other toxic elements were detected with values above maximum allowed concentrations for drinking water. The wells of rural households had increased levels of Fe and Mn, as well as the increased mineralization, conductivity, and nitrogen cycle. The concentration of heavy metals in water wells was increased in the most settlements around Bela Crkva, as well as in Cesko Selo, Banatska Subotica, Kustilj, Jablanka and Karas river. From the water accumulations formed in the Quaternary sediments southwest from Bela Crkva, samples of water, mud, overbank sediments, and A-horizon were collected. The water samles were determined on: Na, K, Ca, Mg, Fe, Mn, Al, NH4, NO3, SO4, HCO3, Cl, F, Ep, Eh, pH value, mineralization, Pb, Cd, Co, Ni, Cr, Cu, Zn, H2S, O2, CO2, U, Ra, Rn, As, Hg, Br. In the solid samples, Au, Ag, Pb, Zn, and other elements, as well as the content of 238U, 232Th and 40K were determined. Test results are presented in tables, diagrams, and hydrogeochemical maps.

Hydrogeological-Geochemical Characteristics of Groundwater in East Banat, Pannonian Basin, Serbia

Eastern Banat is the eastern part of Vojvodina Province, southern belt of the Pannonian Basin, a surface area of some 505 km2 in NE Serbia (Fig. 1). It is rolling country at altitudes between 75 and 100 metres. The largest positive morphologic feature is Vrsac Mountains that extend eastward to the Romanian-Serbian border. The Mountains occupy an area of 170 km2 surrounded by Mali Rit and Markovac stream in the north, Mesic and Guzijana ranges in the south, Vrsac suburbs in the west and Serbian-Romanian border in the east.