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Key Event Title
Deposition of Energy
|Level of Biological Organization|
Key Event Components
Key Event Overview
AOPs Including This Key Event
|AOP Name||Role of event in AOP||Point of Contact||Author Status||OECD Status|
|Deposition of energy leading to lung cancer||MolecularInitiatingEvent||Vinita Chauhan (send email)||Open for citation & comment||WPHA/WNT Endorsed|
|Ionizing Radiation-Induced AML||MolecularInitiatingEvent||Dag Anders Brede (send email)||Under development: Not open for comment. Do not cite|
|ROS production leading to population decline via photosynthesis inhibition||MolecularInitiatingEvent||Knut Erik Tollefsen (send email)||Under development: Not open for comment. Do not cite|
|ROS production leading to population decline via mitochondrial dysfunction||MolecularInitiatingEvent||Knut Erik Tollefsen (send email)||Under development: Not open for comment. Do not cite|
|DNA damage leading to population decline via programmed cell death||MolecularInitiatingEvent||Knut Erik Tollefsen (send email)||Under development: Not open for comment. Do not cite|
|Deposition of ionising energy leads to population decline via pollen abnormal||MolecularInitiatingEvent||Li Xie (send email)||Under development: Not open for comment. Do not cite|
|Deposition of energy leading to population decline via DSB and follicular atresia||MolecularInitiatingEvent||Knut Erik Tollefsen (send email)||Under development: Not open for comment. Do not cite|
|Deposition of energy leading to population decline via DSB and apoptosis||MolecularInitiatingEvent||Knut Erik Tollefsen (send email)||Under development: Not open for comment. Do not cite|
|Energy deposition leading to population decline via DNA oxidation and oocyte apoptosis||MolecularInitiatingEvent||You Song (send email)||Under development: Not open for comment. Do not cite|
|Energy deposition leading to population decline via DNA oxidation and follicular atresia||MolecularInitiatingEvent||You Song (send email)||Under development: Not open for comment. Do not cite|
|Increased DNA damages during embryonic development lead to microcephaly||MolecularInitiatingEvent||Olivier ARMANT (send email)||Under development: Not open for comment. Do not cite|
|Deposition of energy leads to reduced cocoon hatchability||MolecularInitiatingEvent||Deborah Oughton (send email)||Under development: Not open for comment. Do not cite|
|Deposition of energy leads to vascular remodeling||MolecularInitiatingEvent||Vinita Chauhan (send email)||Open for citation & comment|
|Energy deposition from Ra226 decay lowers oxygen binding capacity of hemocyanin||MolecularInitiatingEvent||Danielle Beaton (send email)||Under development: Not open for comment. Do not cite|
|Deposition of energy leading to cataracts||MolecularInitiatingEvent||Vinita Chauhan (send email)||Open for citation & comment|
|Deposition of energy leading to bone loss||MolecularInitiatingEvent||Vinita Chauhan (send email)||Open for citation & comment|
|Deposition of Energy Leading to Learning and Memory Impairment||MolecularInitiatingEvent||Vinita Chauhan (send email)||Open for citation & comment|
|Scotch pine||Pinus sylvestris||Moderate||NCBI|
|Daphnia magna||Daphnia magna||High||NCBI|
|Chlamydomonas reinhardtii||Chlamydomonas reinhardtii||Moderate||NCBI|
|common brandling worm||eisenia fetida||Moderate||NCBI|
|Lemna minor||Lemna minor||High||NCBI|
|Salmo salar||Salmo salar||Low||NCBI|
|All life stages||High|
Key Event Description
Deposition of energy refers to events where energetic subatomic particles, nuclei, or electromagnetic radiation deposit energy in the media through which they transverse. The energy may either be sufficient (e.g. ionizing radiation) or insufficient (e.g. non-ionizing radiation) to ionize atoms or molecules (Beir et al.,1999).
Ionizing radiation can cause the ejection of electrons from atoms and molecules, thereby resulting in their ionization and the breakage of chemical bonds. The energy of these subatomic particles or electromagnetic waves mostly range from 124 KeV to 5.4 MeV and is dependent on the source and type of radiation (Zyla et al., 2020). To be ionizing the incident radiation must have sufficient energy to free electrons from atomic or molecular electron orbitals. The energy deposited can induce direct and indirect ionization events and this can be via internal (injections, inhalation, or absorption of radionuclides) or external exposure from radiation fields -- this also applies to non-ionizing radiation.
Direct ionization is the principal path where charged particles interact with biological structures such as DNA, proteins or membranes to cause biological damage. Photons, which are electromagnetic waves can also deposit energy to cause direct ionization. Ionization of water, which is a major constituent of tissues and organs, produces free radical and molecular species, which themselves can indirectly damage critical targets such as DNA (Beir et al., 1999; Balagamwala et al., 2013) or alter cellular processes. Given the fundamental nature of energy deposition by radioactive/unstable nuclei, nucleons or elementary particles in material, this process is universal to all biological contexts.
The spatial structure of ionizing energy deposition along the resulting particle track is represented as linear energy transfer (LET) (Hall and Giaccia, 2018 UNSCEAR, 2020). High LET refers to energy mostly above 10 keV μm-1 which produces more complex, dense structural damage than low LET radiation (below 10 keV μm-1). Low-LET particles produce sparse ionization events such as photons (X- and gamma rays), as well as high-energy protons. Low LET radiation travels farther into tissue but deposits smaller amounts of energy, whereas high LET radiation, which includes heavy ions, alpha particles and high-energy neutrons, does not travel as far but deposits larger amounts of energy into tissue at the same absorbed dose. The biological effect of the deposition of energy can be modulated by varying dose and dose rate of exposure, such as acute, chronic, or fractionated exposures (Hall and Giaccia, 2018).
Non-ionizing radiation is electromagnetic waves that does not have enough energy to break bonds and induce ion formation but it can cause molecules to excite and vibrate faster resulting in biological effects. Examples of non-ionizing radiation include radio waves (wavelength: 100 km-1m), microwaves (wavelength: 1m-1mm), infrared radiation (wavelength: 1mm- 1 um), visible light (wavelengths: 400-700 nm), and ultraviolet radiation of longer wavelengths such as UVB (wavelengths: 315-400nm) and UVA (wavelengths: 280-315 nm). UVC radiation (200-280 nm) is, in contrast to UVB and UVA, considered to be a type of ionizing radiation.
How It Is Measured or Detected
OECD Approved Assay
Monte Carlo Simulations (Geant4)
Douglass et al., 2013; Douglass et al. 2012; Zyla et al., 2020
Monte Carlo simulations are based on a computational algorithm that mathematically models the deposition of energy into materials.
Fluorescent Nuclear Track Detector (FNTD)
Sawakuchi, 2016; Niklas, 2013; Koaira & Konishi, 2015
FNTDs are biocompatible chips with crystals of aluminium oxide doped with carbon and magnesium; used in conjuction with fluorescent microscopy, these FNTDs allow for the visualization and the linear energy transfer (LET) quantification of tracks produced by the deposition of energy into a material.
|Ionizing radiation||Tissue equivalent proportional counter (TEPC)||Straume et al, 2015||Measure the LET spectrum and calculate the dose equivalent.||No|
|Ionizing radiation||alanine dosimeters/NanoDots||
Lind et al. 2019; Xie et al., 2022
|Non-ionizing radiation||UV meters or radiameters||Xie et at., 2020||UVA/UVB (irradiance intensity), UV dosimeters (accumulated irradiance over time), Spectrophoto meter (absorption of UV by a substance or material)||No|
Domain of Applicability
Energy can be deposited into any substrate, both living and non-living; it is independent of age, taxa, sex, or life-stage.
Taxonomic applicability: This MIE is not taxonomically specific.
Life stage applicability: This MIE is not life stage specific.
Sex applicability: This MIE is not sex specific.
Balagamwala, E. H. et al. (2013), “Introduction to radiotherapy and standard teletherapy techniques”, Dev Ophthalmol, Vol. 52, Karger, Basel, https://doi.org/10.1159/000351045
Beir, V. et al. (1999), “The Mechanistic Basis of Radon-Induced Lung Cancer”, in Health Risks of Exposure to Radon: BEIR VI, National Academy Press, Washington, D.C., https://doi.org/10.17226/5499
Douglass, M. et al. (2013), “Monte Carlo investigation of the increased radiation deposition due to gold nanoparticles using kilovoltage and megavoltage photons in a 3D randomized cell model”, Medical Physics, Vol. 40/7, American Institute of Physics, College Park, https://doi.org/10.1118/1.4808150
Douglass, M. et al. (2012), “Development of a randomized 3D cell model for Monte Carlo microdosimetry simulations.”, Medical Physics, Vol. 39/6, American Institute of Physics, College Park, https://doi.org/10.1118/1.4719963
Hall, E. J. and Giaccia, A.J. (2018), Radiobiology for the Radiologist, 8th edition, Wolters Kluwer, Philadelphia.
Kodaira, S. and Konishi, T. (2015), “Co-visualization of DNA damage and ion traversals in live mammalian cells using a fluorescent nuclear track detector.”, Journal of Radiation Research, Vol. 56/2, Oxford University Press, Oxford, https://doi.org/10.1093/jrr/rru091
Lind, O.C., D.H. Oughton and Salbu B. (2019), "The NMBU FIGARO low dose irradiation facility", International Journal of Radiation Biology, Vol. 95/1, Taylor & Francis, London, https://doi.org/10.1080/09553002.2018.1516906.
Sawakuchi, G.O. and Akselrod, M.S. (2016), “Nanoscale measurements of proton tracks using fluorescent nuclear track detectors.”, Medical Physics, Vol. 43/5, American Institute of Physics, College Park, https://doi.org/10.1118/1.4947128
Straume, T. et al. (2015), “Compact Tissue-equivalent Proportional Counter for Deep Space Human Missions.”, Health physics, Vol. 109/4, Lippincott Williams & Wilkins, Philadelphia, https://doi.org/10.1097/HP.0000000000000334
Niklas, M. et al. (2013), “Engineering cell-fluorescent ion track hybrid detectors.”, Radiation Oncology, Vol. 8/104, BioMed Central, London, https://doi.org/10.1186/1748-717X-8-141
UNSCEAR (2020), Sources, effects and risks of ionizing radiation, United Nations.
Xie, Li. et al. (2022), "Ultraviolet B Modulates Gamma Radiation-Induced Stress Responses in Lemna Minor at Multiple Levels of Biological Organisation", SSRN, Elsevier, Amsterdam, http://dx.doi.org/10.2139/ssrn.4081705 .
Zyla, P.A. et al. (2020), Review of particle physics: Progress of Theoretical and Experimental Physics, 2020 Edition, Oxford University Press, Oxford.