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.

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.

Arsenic contamination in environment in the region of Vojvodina.

Ground waters in the region of Autonomous Province of Vojvodina, Republic of Serbia are endangered by arsenic (up to 0.750 mg/l). Total arsenic concentration was determined In samples of untreated and treated water from some local and central water-supply systems. Results are compared to actual regulations in the country. This analysis encompassed 324 drinking water samples of various sources, analyzed in the Institute of Public Health Novi Sad, during 2005. Determined concentration of total arsenic in drinking water varies from 0.005 to 0.450 mg/l. Arsenic concentration in the river Danube water was within recommended value for I-II class. Maximum arsenic daily intake through food and nutrition was 60.9 +/- 22.3 microg/day in 2000. To understand importance of the problem of arsenic environment contamination in Vojvodina region, our own results, as well as the results of other authors are presented and analyzed (drinking water: 173 samples, moss deposition and daily intake through nutrition).

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 Celije Reservoir and from Krusevac town-supplied tap water from that reservoir two days later. Concentration of microcystin-LR was 650 microg L(-1) in the reservoir, while the tap water contained 2.5 microg L(-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 (Toplicki, Niski, and Sumadijski 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.

Cd and Zn in atmospheric deposit, soil, wheat, and milk.

Continuous air quality monitoring in the Vojvodina district of Serbia and Montenegro has shown high levels of Cd, especially in the outskirts of large towns such as Kikinda. The construction and metal processing industries located in Kikinda have been emitting significant amounts of heavy metals into the environment. The levels of Cd and Zn were monitored in the region of Kikinda and compared to their concentrations detected in Novi Sad, the capital of Vojovodina, where emission of heavy metals originated mostly from vehicle traffic. The study was performed during the economic sanctions when industrial production decreased drastically. The consequence of that was a significant decrease of the concentration of Cd and Zn in atmospheric deposits. Data collected during 3 years indicated a direct influence of atmospheric deposits on heavy metal distribution in the chain soil-cattle feed-milk. Decreased Cd concentrations of 93% in atmospheric deposits in the Kikinda region resulted in decreased Cd concentrations of 17% in cattle feeds and 13% in milk. Decreased Zn concentrations of 58% in atmospheric deposits caused reduced Zn concentrations of 30% in soil, 17% in cattle feeds, and 17% in milk.