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The content of heavy metals in mineralised dental tissues is an indicator of the exposure of their mineral phase to heavy metals during the time of tooth development and dental tissue formation. Therefore, teeth have been used as bio-indicators which accurately reflect the environmental or dietary exposure of animals and humans to heavy metals. This study follows from the earlier work in which it was demonstrated that the teeth from bank voles inhabiting various environmentally polluted and non-polluted forests in Southern Poland were reliable indicators of exposure to heavy metals. Using analytical techniques employed in the earlier study heavy metal concentrations were obtained in the teeth of bank voles trapped in 1998-2000 to determine if efforts to clean up the environment could be detected in changes in heavy metal concentrations in the teeth. The results show that these efforts are reflected in lower concentrations of heavy metals in the teeth but that cross border contamination remains a problem.

This investigation is based on the premise that heavy metals are sequestered by the mineral phase of teeth, hydroxyapatite, during their formation. Once formed these tissues are not subject to significant turnover and it is suggested, therefore, that they provide a permanent and cumulative record of heavy metal exposure during the development of the teeth. The teeth of the bank vole (Clethrionomys glareolus) were analysed by inductively coupled plasma mass spectrometry to monitor the animals' exposure to lead, cadmium, zinc, copper and strontium. Animals were trapped in clean and polluted areas in Poland in and around Krakow in 1996 and in Olkusz and Legnica in 1996 and 1997. The control area in 1996 was Bieszcady National Park and in 1997 Borecka Forest. The results showed that there were statistically different concentrations of heavy metals in the teeth of animals from different sites. The high levels of pollution from industrial emissions were related to higher concentrations of heavy metals in the teeth. Unexpectedly high levels of heavy metals in the teeth of animals from Bieszczady National Park, thought to be environmentally clean, suggested cross-border pollution from Slovakia and the Ukraine. It was concluded that the teeth of small mammals, such as the bank vole, are a sensitive and reliable marker of environmental pollution by heavy metals.

Concentrations of heavy metals (Cd, Pb, Cu, Zn, Fe) were determined in the tissues of bank voles collected in polluted forest sites in southern Poland and in Białowieza National Park. The highest cadmium concentrations were found in livers (0.9-12.8 microg g(-1)) and kidneys (3.2-29.6 microg g(-1)), whereas the lowest were in bones (0.2-0.9 microg g(-1)). The lead concentrations found in kidneys and bones ranged from 9.5 to 40.0 microg g(-1). The ranges of zinc, iron and copper concentrations in the tissues of animals were: 137-343 microg g(-1), 206-1017 microg(-1) and 12.0-73.8 microg(-1), respectively. Some of the differences between the levels found in various sites were statistically significant.