Study of heavy metals element of lead and cadmium in archaeological bones (case study: Valiran in Damavand)

Valiran is a Parthian archaeological site situated near Valiran village in the central region of Damavand city. In this site, stratum structure remained of Sassanian time has been discovered. This village is in 1.5 km south of Damavand city in east of Tehran. This archaeological site was discovered accidentally and then excavated by Nemati in 2006 summer. Sitting on throne, Parthian governed on the north east of Iran at least a century. They gradually overthrew Seleucid and extended their territory to the center and the west of Iran. They occupied Raga which was an important Parthian city possibly for military purposes. Several buried skeleton and residue of cereal have been reported by the excavator. Seven silver coins were found from Mithradate II and Senatruces, Mithradate III, Orodes II and Gotarzes I, Parthian kings. The animal bone and teeth was been extracted from Sassanian strata Lead and Cadmium are among the heavy metals that are rare in soil, water, plants, animal and human. These heavy metals are absorbed to humans and animals' bodies through eating, inhalation, and skin contact. Lead is a biogeochemical analog role and is only present as a contamination in the body. Lead and Cadmium are of high importance because of their long half-life in humans and animals' body and their toxicity. In this study, dental specimens of 10 human skeletons of the historical site of Valiran in Damavand belonging to the Parthian era were tested to determine their level of lead and cadmium by means of Atomic Absorption Spectroscopy Faculty of Medical Sciences Tarbiat Modares University. At first, we washed teeth samples which are taken from archaeological Site by soft brush and water drops to remove dust from that. Then we placed them into distillated water to erase organic materials of samples surface. After that we placed samples about 12 hours at 80 0C temperature to dry them completely. Finally, we sent them to be tested by the Atomic Absorption Spectroscopy Faculty of Medical Sciences Tarbiat Modares University of Tehran. This study showed high levels of lead and cadmium in the specimens. The level of lead in the specimens varied from 148 to 380 ppm and the level of cadmium in them ranged from 20 to 103 ppm. Since lead and cadmium are an indication of pollution in archeological studies, these high levels of lead and cadmium may have been absorbed to body as a result of factors, such as nutrition and the type of drinking water, the conduct of metalworking activities, and diseases. Considering the variety of factors that have possible led to the contamination of specimens with lead and cadmium, it seems that feeding diet and use of spring water have been the main factors in the high levels of lead and cadmium in ancient specimens. In addition, the presence of soil in the vicinity of the site can be another factor that has led to the increased levels of lead and cadmium in the soil and human skeletons over time.