Download Iodine isotopes in forensic science and anthropology I and I are both

Stable
isotope
127
I
Relative
atomic mass
126.904 47
Mole
fraction
1
Iodine isotopes in forensic science and anthropology
131
I and 129I are both fission products; however, 129I is a long-lived fission product that can be
helpful in the detection of the movement of radiation after a radioactive event, such as occurred
at the Japanese reactors at Fukushima. In nuclear reactors and weapons tests, uranium and
plutonium undergo fission processes in which one of the fission products is the long-lived
isotope 129I. This isotope can be used as a groundwater tracer to determine evidence of nuclear
fission, and it can also be tracked in rainwater as evidence of a fission event in the air (weapons
explosion; Figure 1) [392-394].
Fig. 1: Global distribution of 129I before the Fukushima disaster in Japan. (Image Source:
Snyder, G., A. Aldahan, and G. Possnert, 2010) [394].
Iodine isotopes in geochronology
Natural cosmogenic 129I enters groundwater and other terrestrial environments from the
atmosphere and then decays to 129 Xe. The isotope-amount ratio n(129I)/ n(127I) can be used as a
clock to estimate time since cosmogenic 129I entered the system. The amount of product 129 Xe in
such cases is too small to measure; however, excess quantities of 129 Xe can be found in
meteorites and other very old samples that contained extinct primordial (substance present since
the formation of the solar system) 129 I. Younger water bodies also can be differentiated from
older water bodies by the relative amount of anthropogenic 129I released since the 1960s from
sources such as nuclear bomb tests [395, 396].
Iodine isotopes in medicine
125
I, which has a half-life of about 59 days, is used encapsulated in radiotherapy to target and
treat sites of cancerous tumors [397]. 120I and 124I are radioactive isotopes that emit positrons
and they are used in quantitative, diagnostic imaging of the body using positron emission
tomography (PET) [385-387, 389-391]. 123I or 131I can be used with single-photon emission
computed spectroscopy (SPECT) for basic three-dimensional imaging [388, 389, 391, 397].
Glossary
alpha particle – a positively charged nuclear particle identical with the nucleus of a helium atom
consisting of two protons and two neutrons.
anthropogenic – resulting from human activity. [return]
atomic number (Z) – The number of protons in the nucleus of an atom.
chondrites (or chondritic meteorites) – non-metallic meteorites which have not undergone
compositional change due to melting because they were part of primitive asteroids, and thus
reflect the composition of the solar nebula from which our Solar System formed.
cosmogenic – produced by the interaction of Earth materials (soil, rock, and atmosphere) and
meteorites with high-energy cosmic rays, resulting in protons and neutrons being expelled
from an atom (termed cosmic ray spallation). [return]
cosmic rays – extremely high-energy radiation, mainly originating outside the Solar System,
consisting of one or more charged particles, such as protons, alpha particles, and larger atomic
nuclei.
CT scan (X-ray computed tomography or X-ray CT, computerized axial tomography scan
or CAT scan) – a computerized tomography (CT) scan combines a series of X-ray images taken
from different angles and uses computer processing to create cross-sectional images, or slices, of
the bones, blood vessels and soft tissues inside your body [702].
electron – elementary particle of matter with a negative electric charge and a rest mass of about
9.109 × 10–31 kg.
element (chemical element) – a species of atoms; all atoms with the same number of protons in
the atomic nucleus. A pure chemical substance composed of atoms with the same number of
protons in the atomic nucleus [703].
fission – the spontaneous (or induced by particle collision) splitting of a heavy nucleus into a
pair (only rarely more) of nearly equal fission fragments (fission products) generally with some
neutrons. Fission is accompanied by the release of a large quantity of energy. [return]
gamma rays (gamma radiation) – a stream of high-energy electromagnetic radiation given off
by an atomic nucleus undergoing radioactive decay. The energies of gamma rays are higher
than those of X-rays; thus, gamma rays have greater penetrating power.
half-life (radioactive) – the time interval that it takes for the total number of atoms of any
radioactive isotope to decay and leave only one-half of the original number of atoms. [return]
isotope – one of two or more species of atoms of a given element (having the same number of
protons in the nucleus) with different atomic masses (different number of neutrons in the
nucleus). The atom can either be a stable isotope or a radioactive isotope.
isotope-amount ratio (r) – amount (symbol n) of an isotope divided by the amount of another
isotope of the chemical element in the same system [706]. [return]
meteorite – a meteoroid that has survived atmospheric passage and fallen to the Earth’s surface
in one or more recoverable fragments. See also chondrites [705]. [return]
neutron – an elementary particle with no net charge and a rest mass of about 1.675 × 10–27 kg,
slightly more than that of the proton. All atoms contain neutrons in their nucleus except for
protium (1H).
positron – the antimatter counterpart of the electron, with a mass identical to that of the electron
and an equal but opposite (positive) charge. [return]
positron emission tomography (PET) scan – an imaging technique that is used to observe
metabolic activity within the body. The system detects pairs of gamma rays emitted indirectly
by a radioactive isotope used as a tracer, which emits positrons and which is introduced into the
body on a biologically-active molecule. Three-dimensional images of the concentration of the
radioactive isotope within the body are then constructed by computer analysis. The imaging
often is performed with an X-ray CT scan in the same instrument. [return]
proton – an elementary particle having a rest mass of about 1.673 × 10–27 kg, slightly less than
that of a neutron, and a positive electric charge equal and opposite to that of the electron. The
number of protons in the nucleus of an atom is the atomic number.
radioactive decay – the process by which unstable (or radioactive) isotopes lose energy by
emitting alpha particles (helium nuclei), beta particles (positive or negative electrons), gamma
radiation, neutrons or protons to reach a final stable energy state.
radioactive isotope (radioisotope) – an atom for which radioactive decay has been
experimentally measured (also see half-life). [return]
radiotherapy (radiation therapy) – the treatment of disease by means of radiation from
radioactive substances or X-rays. [return]
single-photon emission computed spectroscopy (SPECT) – a nuclear medicine imaging
technique that is able to provide true three-dimensional information using gamma rays from a
radiopharmaceutical. [return]
solar nebula – the cloud of dust and gas from which the solar system is believed to have
condensed, mainly by gravitational attraction about 4.5 billion years ago.
spallation – a process in which fragments of a solid (spall) are ejected from the solid due to
impact or stress. In nuclear physics, spallation is the process in which a nucleus of a heavy
element emits a large number of nucleons (isotopes) as a result of being hit by a high-energy
particle (e.g., a cosmic ray), resulting is a substantial loss of its atomic weight.
stable isotope – an atom for which no radioactive decay has ever been experimentally measured.
tracer - substance used for tracking purposes. [return]
X-rays – electromagnetic radiation with a wavelength ranging from 0.01 to 10 nanometers—
shorter than those of UV rays and typically longer than those of gamma rays.
References
385. A. Hohn, Coenen, H.H., and Qaim, S.M. Applied Radiation and Isotopes. 49 (12), 1493
(1998).
386. H. Herzog, Qaim, S.M., Tellmann, L., Spellerberg, S., Kruecker, D., and Coenen, H.H.
European Journal of Nuclear Medicine and Molecular Imaging. 33 (11), 1249 (2006).
387. A. Hohn, Scholten, B., Coenen, H.H., and Qaim, S.M. Applied Radiation and Isotopes.
49 (1-2), 93 (1998).
388. T. Kakavand, Sadeghi, M., Moghaddam, K.K., Bonab, S.S., and Fateh, B. Iranian
Journal of Radiation Research. 5 (4), 207 (2008).
389. M. L. Firouzbakht, Schlyer, D.J., Finn, R.D., Laguzzi, G., and Wolf, A.P. Nuclear
Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and
Atoms. 79 (1-4), 909 (1993).
390. H. Herzog, Tellman, L., Qaim, S.M., Spellerberg, S., Schmid, A., and Coenen, H.H.
Applied Radiation and Isotopes. 56 (5), 673 (2002).
391. F. T. Lee, Hall, C., Rigopoulos, A., Zweit, J., Pathmaraj, K., O’Keefe, G.J., Smyth F.E.,
Welt, S., Old, L.J., and Scott, A.M. The Journal of Nuclear Medicine. 42 (5), 764 (2001).
392. D. Elmore, Gove, H.E., Ferraro, R., Kilius, L.R., Lee, H.W., Chang, K.H., Beukens, R.P.,
Litherland, A.E., Russo, C.J., Purser, K.H., Murrell, M.T., and Finkel, R.C. Nature. 286, 138
(1980). 10.1038/286138a0
393. G. Snyder, and Fehn, U. Nuclear Instruments and Methods in Physics Research Section
B: Beam Interactions with Materials and Atoms. 223, 579 (2004). 10.1016/j.nimb.2004.04.107
394. G. Snyder, Aldahan, A., and Possnert, G. Geochemistry Geophysics Geosystems. 11 (4)
(2010). 10.1029/2009GC002910
395. P. H. Santschi, Moran, J.E., Oktay, S., Hoehn, E., and Sharma, P. In International
Symposium on Isotope Techniques in Water Resources Development and Management, Vienna,
Austria (1999).
396. G. M. Raisbeck, Yiou, F., Zhou, Z.Q., and Kilius, L.R. Journal of Marine Systems. 6 (56), 561 (1995). 10.1016/0924-7963(95)00024-J
397. V. R. Narra, Howell, R.W., Harapanhalli, R.S., Sastry, K.S., and Rao, D.V. Journal of
Nuclear Medicine. 33 (12), 2196 (1992).
702. M. Clinic. Test and Procedures: CT scan. 2016 June 22.
http://www.mayoclinic.org/tests-procedures/ct-scan/basics/definition/prc-20014610
703. I. U. o. P. a. A. Chemistry. Compendium of Chemical Terminology, 2nd ed. (the "Gold
Book"). Blackwell Scientific Publications, Oxford (1997).
706. Coplen. Rapid Communications in Mass Spectrometry. 25 (2011).