Ten Thousand Years of Environment Assessment Using
Synchrotron Radiation Micro Beam
K. Shirasawa*, A. Ide-Ektessabi†+, A. Koizumi¶, and M. Azechi¶
*
Graduate School of Engineering, Kyoto University, Yoshida Honnmachi, Sakyou-ku, Kyoto, 606-8501, Japan
International Innovation Center, Kyoto University, Yoshida Honnmachi, Sakyou-ku, Kyoto, 606-8501, Japan
¶
Graduate School of Medicine, Kyoto University, Department of Health and Environment Sciences,
Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
†
Abstract. The environment surrounding human has changed through civilization and industrialization, and through
these developments, problems including the pollution from heavy metals such as lead and mercury have arisen. In this
study, we analyzed major and trace elements in modern and prehistoric teeth by x-ray fluorescence (XRF) analysis using
synchrotron radiation micro beam, in order to assess the changes of the environment through the civilization and the
industrialization and their affects to the human. It is suggested that teeth accumulate elements in the mineral phase,
hydroxiapatite, during their formation, and because there are no significant turnovers, teeth are concerned to be
indicators of the environment of the donor. We first analyzed the elements on the surface of tooth from modern
individual and tooth from human remains of Jomon period to assess the heavy metal concentration and effect of the
diagenesis. The adhering ground elements on the prehistoric teeth showed high amount of Ti, Fe, Mn and other metallic
elements.
The advantage of teeth as indicators of the
environment is that elements including heavy metals
such as lead and mercury 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 permanent and cumulative information of
the donor’s environment. [10] Enamel for instance,
forms at known stages of life and is chemically stable
in vivo whereas dentin is remodeled in apredictable
fashion. The relative stability of enamel is reflected in
its excellent post-mortem preservation.
In this study, the enamel surfaces of the modern
tooth and tooth from the human remains of the Jomon
period were analyzed using synchrotron radiation
micro beam in order to assess the heavy metal
concentration and discuss the effect of the diagenesis
on the enamel surface of the teeth.
INTRODUCTION
X-ray
fluorescent
(XRF)
analysis
using
synchrotron radiation micro beam is a powerful
method for trace element analysis. Recent
developments in synchrotron radiation source provide
the impetus for XRF studies, with detection limits and
spatial resolution being improved. [1] Due to these
improvements, XRF analyses have been used in
various fields including biomedical fields. [2-6] In this
study, we applied synchrotron radiation micro beam to
the field of environment assessment.
The environment surrounding human has changed
through civilization and industrialization, and through
these developments, problems including the pollution
from heavy metals such as lead and mercury have
arisen. [7-9] The pollution from heavy metals is now
believed to be considerably greater than it was in the
remote past. The aim of our study is to assess the
change of the pollution in a very long term by
analyzing the heavy metals accumulated in the teeth as
an indicator of the environment.
+
Corresponding author: Ari Ide-Ektessabi, Email: [email protected]
CP680, Application of Accelerators in Research and Industry: 17th Int'l. Conference, edited by J. L. Duggan and I. L. Morgan
© 2003 American Institute of Physics 0-7354-0149-7/03/$20.00
522
of each group. Ca, Ti, Mn, Fe, Ni, Cu, Zn, Hg, Pb and
Br were the elements detected.
As there is no reliable hydroxyapatite standard,
quantitative analysis is unavailable, but as the there are
slight difference in calcium level in teeth, calcium
appear to offer the best choice for an internal standard.
Therefore, the XRF data are presented as Pb/Ca,
Hg/Ca, Fe/Ca, Ti/Ca, Mn/Ca, Cu/Ca, Zn/Ca, Ni/Ca
ratios. Figure 3 shows the ratios of each measurement
point standardized by the maximum value of each
elements. The ratios of each element are divided into
three groups as marked before.
High levels of Pb and Hg were observed in the
modern tooth compared to the Jomon tooth. This fact
is important as it supports the belief that the pollution
from heavy metals is now considerably greater than it
was in the remote past. The levels are higher in the
Jomon tooth with ground elements than without them.
Cu ratio of modern tooth also shows a higher level
than of Jomon tooth. The extremely high levels of Fe,
Ti and Mn were observed in the ground elements
covering the Jomon tooth, which suggests that these
elements are mainly due to the ground elements.
Therefore removing the adhering soils and cleaning
the surface carefully may remove their effects of
diagenesis. Zn and Ni did not show significant
difference in three groups. The cause of high level of
Ni at one point of the covering ground elements is
unknown.
As this study covers only one set of samples (one
modern tooth and one Jomon tooth), further study of
various teeth is needed to see detail information of the
diagenesis. However, the high concentration of Pb and
Hg in modern tooth supports the suggestion that
pollution from such heavy metals is greater now than
in the Jomon period.
FIGURE 1. A photograph of a cross section of a tooth from
a modern indivisual.
EXPERIMENTAL
Two teeth samples were collected for XRF analysis
using synchrotron radiation micro beam. One was
collected from a modern individual and the other was
collected from the human remains of the Jomon period.
The Jomon tooth was partly covered with ground
elements. Figure 1 shows a photograph of a cross
section of a tooth from a modern individual. Enamel is
suggested to be the most stable tissue of the teeth.
XRF analyses using synchrotron radiation micro
beam were performed at the Photon Factory, KEK
(Tsukuba, Japan). Synchrotron radiation from the
storage ring (2.5 GeV, maximum current 400 mA) was
monochromated by a multilayer film monochromator.
The incident x-ray energy was 14.2 keV. Incident xrays were focused using Kirkpatrick-Baez optics. The
incident beam size was about 7 x 6 μm. The incident
and transmitted photon flux was monitored with an ion
chamber, and the fluorescent x-rays were collected by
a solid-state detector (SSD). Measurements were
performed in air.
CaKα
Modern
Jomon
Jomon (w/ ground elements)
10000
CaKβ
ZnKα
Fluoresent Count
Fe
RESULTS AND DISCUSSIONS
1000
P,Ca(esc)
Ar
100
Mn
S
Cl
ZnKβ
FeKβ
Ni
TiKα
Pb
Cu
TiKβ
Br
Hg
10
XRF analysis using synchrotron radiation micro
beam was performed on the surface of modern and
Jomon teeth. Five points on the modern tooth and ten
points on the Jomon tooth were analyzed. Five of ten
points on Jomon tooth were on the area where the
ground elements covered the surface. The
measurement points can be divided into three groups,
modern tooth, Jomon tooth and Jomon tooth with
ground elements. Figure 2 shows the typical spectrum
1
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Energy (keV)
FIGURE 2. Typical spectra of three different groups of
measurement points, modern tooth, Jomon tooth, and Jomon
tooth with ground elements.
523
1.0
0.8
0.8
Hg/Ca Ratio
Pb/Ca Ratio
1.0
0.6
0.4
0.2
0.0
Jomon
Jomon
(w/ground elements)
1.0
1.0
0.8
0.8
Fe/Ca Ratio
Ti/Ca Ratio
Modern
0.6
0.4
0.2
Modern
Jomon
Jomon
(w/ground elements)
Modern
Jomon
Jomon
(w/ground elements)
Modern
Jomon
Jomon
(w/ground elements)
Modern
Jomon
Jomon
(w/ground elements)
0.6
0.4
0.2
0.0
0.0
Modern
Jomon
Jomon
(w/ground elements)
1.0
1.0
0.8
0.8
Cu/Ca Ratio
Mn/Ca Ratio
0.4
0.2
0.0
0.6
0.4
0.2
0.6
0.4
0.2
0.0
0.0
Modern
Jomon
Jomon
(w/ground elements)
1.0
1.0
0.8
0.8
Ni/Ca Ratio
Zn/Ca Ratio
0.6
0.6
0.4
0.2
0.6
0.4
0.2
0.0
0.0
Modern
Jomon
Jomon
(w/ground elements)
FIGURE 3. Pb/Ca, Hg/Ca, Fe/Ca, Ti/Ca, Mn/Ca, Cu/Ca, Zn/Ca, Ni/Ca ratios of each measurement point.
524
ACKNOWLEDGEMENTS
The micro beam XRF analysis was performed at
Photon Factory in the High Energy Accelerator
Research Organization, Tsukuba, Japan (Project
No.2002G172). The authors express their thanks to
Professor Atuo Iida of Photon Factory
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