312
A. Gnamus and M. Horvat
also be prevented by effective defence mechanism such as efficient Hg
elimination through litterfall. In our present study, Hg concentration levels in
plants were higher than in most animal tissues from the contaminated area.
Apparently, relatively effective mechanisms for Hg detoxification and elimination were developed through the phylogenetic development of the organisms in
the heavily polluted area. However, since the higher plants and animal indicators
show no toxic effects to relatively high mercury concentrations, a comparative
study focused on detoxifying mechanisms in plants (including the metal
complexing pep tides called phytochelatins) and similar mechanisms (metallothioneins) in animals could be instructive.
4.9
Wildlife as an Early Warning for Human Health Hazards
of Hg Contamination?
Comparison of the present results on roe deer tissues with data on the Idrijan
and control human populations in the 1970S and 1980s shows relatively good
agreement (Table 7; Byrne et al. 1971; Kosta et al. 1972, 1974a,b,c; 1975; Zelenko
1986; Horvat et al. 1991). Although the most extensive study on humans was
performed about 25 years ago, when the mercury mine and smelting plant
discharged several tens of kilograms of Hg per day into the air, the former data is
comparable with those in the present study, as shown in Table 7. The exceptions
are pituitary and brain cortex with significantly lower mercury concentrations in
roe deer compared to the values measured in these tissues of the Idrijan human
residents. It is possible that these high concentrations of mercury in human brain
and endocrine system are the consequence of the high physiological and
metabolic activity of these tissues in man. To elucidate this problem, a special
study should be designed. However, most of the present roe deer tissue Hg
concentrations are even higher than those in comparable human tissues obtained
15 to 25 years ago (Byrne et al. 1971; Kosta et al. 1972, 1974a,b,c; 1975; Zelenko 1986;
Horvat et al. 1991) (see also Fig. sa: herbivores vs. man). These comparisons
indicate that roe deer tissue concentrations may be used as an early warning of
elevated Hg tissue values in humans. If any cytogenetic or histological changes in
selected roe deer tissues are found, we may predict similar adverse effects of high
Hg concentration would be found in human tissues. Further investigations and
comparative studies of the present situation in humans is needed to confirm the
above and to indicate which roe deer tissues are the most suitable for comparison
and for mercury intoxication risk assessments in humans.
4.10
The Prey:Predator Relationship as a Reflection
of Territorial Hg Contamination
A summary of the average T-Hg and Me-Hg concentrations in various samples
from the terrestrial environment in the Idrija area and unpolluted control areas
A. Gnamus and M. Horvat
also be prevented by effective defence mechanism such as efficient Hg
elimination through litterfall. In our present study, Hg concentration levels in
plants were higher than in most animal tissues from the contaminated area.
Apparently, relatively effective mechanisms for Hg detoxification and elimination were developed through the phylogenetic development of the organisms in
the heavily polluted area. However, since the higher plants and animal indicators
show no toxic effects to relatively high mercury concentrations, a comparative
study focused on detoxifying mechanisms in plants (including the metal
complexing pep tides called phytochelatins) and similar mechanisms (metallothioneins) in animals could be instructive.
4.9
Wildlife as an Early Warning for Human Health Hazards
of Hg Contamination?
Comparison of the present results on roe deer tissues with data on the Idrijan
and control human populations in the 1970S and 1980s shows relatively good
agreement (Table 7; Byrne et al. 1971; Kosta et al. 1972, 1974a,b,c; 1975; Zelenko
1986; Horvat et al. 1991). Although the most extensive study on humans was
performed about 25 years ago, when the mercury mine and smelting plant
discharged several tens of kilograms of Hg per day into the air, the former data is
comparable with those in the present study, as shown in Table 7. The exceptions
are pituitary and brain cortex with significantly lower mercury concentrations in
roe deer compared to the values measured in these tissues of the Idrijan human
residents. It is possible that these high concentrations of mercury in human brain
and endocrine system are the consequence of the high physiological and
metabolic activity of these tissues in man. To elucidate this problem, a special
study should be designed. However, most of the present roe deer tissue Hg
concentrations are even higher than those in comparable human tissues obtained
15 to 25 years ago (Byrne et al. 1971; Kosta et al. 1972, 1974a,b,c; 1975; Zelenko 1986;
Horvat et al. 1991) (see also Fig. sa: herbivores vs. man). These comparisons
indicate that roe deer tissue concentrations may be used as an early warning of
elevated Hg tissue values in humans. If any cytogenetic or histological changes in
selected roe deer tissues are found, we may predict similar adverse effects of high
Hg concentration would be found in human tissues. Further investigations and
comparative studies of the present situation in humans is needed to confirm the
above and to indicate which roe deer tissues are the most suitable for comparison
and for mercury intoxication risk assessments in humans.
4.10
The Prey:Predator Relationship as a Reflection
of Territorial Hg Contamination
A summary of the average T-Hg and Me-Hg concentrations in various samples
from the terrestrial environment in the Idrija area and unpolluted control areas