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 ?elije Reservoir and from Kru?evac 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 (Topli?ki, Ni?ki, and ?umadijski 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.     

A Population-based Study of Toenail Onychomycosis in Israeli Children

Abstract:   Onychomycosis is widespread in the adult population, but considered to be rare in children. A number of studies in recent years show a rise in the prevalence of toenail onychomycosis in children. Of these, only a few were population-based. Here, we present a comprehensive cross-sectional population-based survey of toenail onychomycosis in primary school children in Israel. The survey included 1148 children, 598 boys, and 550 girls aged 5 to 14 from primary schools in the Jerusalem vicinity. Each child underwent a physical examination and completed a personal questionnaire, which provided background information of predisposing factors. The survey shows a prevalence of 0.87% of toenail onychomycosis. Although this figure is too small for statistical analysis, some important conclusions could be drawn: prevalence increased with age: boy/girl ratio was 2.2; the dominant etiologic agent was Trichophyton rubrum followed by Trichophyton mentagrophytes and Candida albicans . Infections were probably transferred from adults via the environment to children. Infected children came from different socio-economic backgrounds. This condition should be considered in the differential diagnosis of nail diseases in children.     

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.