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Ecosystems

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Scientific papers - Ecosystems - page 5

3. Slovakia CJD cluster (Tables 4-7)
 
CJD has erupted in two distinct isolated foci in central Slovakia (61); one in the north in the Orava district where CJD cases have erupted in a remote group of neighbouring villages located along the western front range of the High Tatra mountains (Fig. 5). And then a smaller cluster of cases in the south, centred around the rural village of Poltar (62-64).Eva Mitrova has identified a genetic risk factor associated with the Slovak CJD foci, but also points to the presence of some hitherto unidentified environmental factor that plays a crucial role in the aetiology of CJD in these two high-risk foci (61).
Despite a protracted spell of sunny, dry weather (which prevents Mn accumulation in plants (31, 65)) prior to the sampling period in September 1999, Mn levels were generally high in the CJD region. A 2 1/2 fold higher concentration of Mn was recorded in the vegetation of the uncultivated pastures of the Orava CJD cluster region in relation to a control sample drawn across a CJD-free area 100 miles East near Poprad (Table 4). Extractable Mn Levels were 'excessive' at 437 mg/kg in Zuberec - the epicentre of the Northern CJD foci (61).
Sampling was largely concentrated around the village of Zuberec in the Orava CJD cluster region (see Fig. 5) and the village of Poltar in the Southern CJD foci because of the high 1 in 1000 CJD risk attached to the residents of these villages (61). Sampling was also carried out in Pucov, since scrapie was first isolated in the sheep of this region (68), although scrapie was thought to have existed more extensively in sheep residing throughout the whole Orava region. Interestingly, pastures in Pucov demonstrated a similar Mn/Cu status (Table 4) to that recorded in Icelandic scrapie endemic regions.
As residents of the Orava region have largely lived a self-sufficient lifestyle growing their foods on allotments surrounding the villages (61), samples of some of their mainstay foods (e.e. potatoes, nuts and cabbage) were taken for analysis. Results demonstrated levels of Mn in excess of the average Mn levels usually associated with these crops (Table 5).
Mn was deficient in samples of the tap and river water supplies currently supplying Zuberec village. However, significant amounts of Mn were detected in the tap water of nearby Malatina village within the CJD region (63) and in Poltar village in the Southern CJD cluster region. Mn was absent in the watersupplies of the CJD-free region (Table 6).
With one exception, Cu and Se were undetectable in all water supplies sampled in the CJD cluster regions. A similar analytical survey (70) was conducted at the Liptovsky Mikulas Health Institute in 1998, where water supplies in the Lipt Sielnica vicinity of the Northern CJD foci were all found to be markedly deficient in Mn/Cu/Se/Zn/Fe.

Table 4   Analyses of herbage/foods sampled across the Slovak CJD cluster zones of Orava/Poltar and CJD-free region of Poprad 23/9/99 to 30/9/99; in mg/kg dry basis, unless marked % w/w

Table 5   Analyses of specific crops cultivated on allotments within the Orava/Poltar CJD
endemic regions 23/9/99 to 30/9/99; in Mg/Kg dry basis or % w/w dry basis

Bracketed figure indicates standard levels of element normally recorded in that specific crop.
Source refs: (69) (4) (3).

Table 6   Analyses of water supplies sampled across the CJD cluster and CJD-free regions of SLOVAKIA 23/9/99 to 30/9/99; in ug/l otherwise mg/l

Table 7   Analyses of topsoils drawn across the CJD cluster and CJD-free regions of Slovakia 23/9/99 to 30/9/99; All elements as extractable mg/l (except Al and H as exchangeable meq/100 g, and Se as 'total' mg/Kg) on a 'dry matter' basis.

Category; L=low N=normal H=high VH=very high

similar Mn/Cu status (Table 4) to that recorded in Icelandic scrapie endemic regions.
As residents of the Orava region have largely lived a self-sufficient lifestyle growing their foods on allotments surrounding the villages (61), samples of some of their mainstay foods (e.e. potatoes, nuts and cabbage) were taken for analysis. Results demonstrated levels of Mn in excess of the average Mn levels usually associated with these crops (Table 5).
Mn was deficient in samples of the tap and river water supplies currently supplying Zuberec village. However, significant amounts of Mn were detected in the tap water of nearby Malatina village within the CJD region (63) and in Poltar village in the Southern CJD cluster region. Mn was absent in the watersupplies of the CJD-free region (Table 6).
With one exception, Cu and Se were undetectable in all water supplies sampled in the CJD cluster regions. A similar analytical survey (70) was conducted at the Liptovsky Mikulas Health Institute in 1998, where water supplies in the Lipt Sielnica vicinity of the Northern CJD foci were all found to be markedly deficient in Mn/Cu/Se/Zn/Fe.

Fig. 5   Distribution of CJD cases in the Northern Orava Valley cluster region of Slovakia in relation to location of ferromanganese factories.   Source (63. 1949 + 1990 (example) = lifetime of CJD case written beside village of origin M = ferromanganese factory. Malatina - village vicinity where samples were taken.

Considering the therapeutic effects of the sulphate ion in arresting the TSE disease process in scrapie affected cell cultures (5), the sixteen fold raised level of sulphate in the CJD-free water supplies in relation to CJD endemic supplies is interesting.
The concentration of metals in Pine needles serves as a sound yardstick for assessing the levels of metal contamination of ecosystems (67);  particularly relevant when assessing the levels of atmospheric metal partculates.
Interestingly, samples of needles collected across a five acre stand of pine trees around CJD endemic Zuberec yielded 951 mg/kg of Mn, whilst a similar collection of needles sampled across the CJD-free region of Poprad yielded only 59 mg/kg of Mn.
Investigation of the environments around the CJD foci for potentially unique sources of atmospheric Mn contamination identified the presence of two large ferromanganese factories sited in the Orava valley at Siroka and Istebne along the North Western boundary of the Northern CJD focus, and the presence of a glass factory (64) (Mn is employed in the glass making process (4)) in Poltar in the Southern CJD foci. Some of the CJD victims had been employed in these factories for varying periods of their working lives. So people working at or living downwind of these factories would have been exposed to significant levels of airborn manganese and silicates in both the Northern and Southern CJD foci.
The factories were originally constructed during the communist era at a time when scant resources were channelled into curtailing chimney emissions of toxic pollutants. Emissions from these factories are locally renowned to form clouds of 'Smog' which travel up the valleys in a Southerly/Easterly direction for several kilometres - precisely over the communities where CJD has erupted. Public fears of atmospheric pollution with manganese dioxide, nickel and other metal compounds downwind of these factories, prompted a study by the Dolny Kubin Health Institute (71) where the hair of children were analyses for metals in the towns of Dolny Kubin (in the Orava CJD cluster region) and Oravska Lesna (outside of the CJD endemic region).       
Interestingly, the results of the 1995 analyses (71) demonstrated 12.945 mg/kg Mn in children resideing in the CJD-endemic Dolny Kubin and 2.832 mg/kg Mn in children residing in the CJD-free Oravska Lesna. Analyses of the other metals in children residing in the two regions did not demonstrate the same significant variation observed with Mn (see Fig. 6).
Fig. 7 demonstrates the decline of Mn levels in children of Dolny Kubin from 15.957 mg/kg Mn measured in 1983 to 9.500 mg.kg measured in 1987 with a subsequent rise back to 12.945 mg/kg measured in 1995. World Health Organization max limit for Mn is 4 mg/kg.
The map of CJD distribution in the Orava region (Fig. 5) demonstrates a North/South Easterly distribution of CJD in relation to the location of the ferromanganese factories along the Orava valley. The distribution of CJD in the villages amidst the Western foothills of the High Tatras correlates with a hypothetical scenario wherein the prevailing westerly winds pick up airborn metal particulates emitted from the factories and carry them the five to fifteen mile journey to the 'rain belt' foothill region, where rainfall delivers the metal pollutants back to the terrestrial ecosystem, contaminating any TSE susceptible genotypes (amongst the local sheep and human populations) dependent on local foodchains rendering them at high risk of developing TSE. The problem of atmospheric Mn contamination may have been compounded further by the presence of other ferromanganese plants located several kilometres away to the North across the Polish border.
Whilst a background incidence of CJD is thought to have existed in TSE susceptible genotypes in the Orava region for many decades (63), it is interesting that incidence rates of CJD did not start to rise until the 1950s (and later scrapie), then peaking later at the high rates encountered in the 1980s - perhaps reflecting a delayed neurotoxic response to the development of the ferromanganese industry in Orava (and glass production in Poltar), where vulnerable early life exposure of Cu deficient individuals to an Mn contaminated environment lead to the formation of Mn misfolded prion protein in the CNS with clinical TSE manifesting many years later in adulthood.

Fig. 6   Hair analyses for metals in children residing in the CJD-endemic region
of dolny kubin and the CJD-free region of oravska lesna 1995; Studey performed
by staff of Dolny Kubin SZU.

Fig. 7   Hair analyses for manganese in children residing in Dolny
Kubin (CJD endemic region). Study performed by staff of Dolny Kubin SZU.

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