NOTE The report of the Committee without its annexes appears as Official Records of the General Assembly, Sixty-third Session, Supplement No. 46. The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the United Nations concerning the legal status of any country, territory, city or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. The country names used in this document are, in most cases, those that were in use at the time the data were collected or the text prepared. In other cases, however, the names have been updated, where this was possible and appropriate, to reflect political changes. Scientific Annexes Annex A. Medical radiation exposures Annex B. Exposures of the public and workers from various sources of radiation INTROdUCTION 1. In the course of the research and development for and the application of atomic energy and nuclear technologies, a number of radiation accidents have occurred. Some of these accidents have resulted in significant health effects and occasionally in fatal outcomes. The application of technologies that make use of radiation is increasingly widespread around the world. Millions of people have occupations related to the use of radiation, and hundreds of millions of individuals benefit from these uses. Facilities using intense radiation sources for energy production and for purposes such as radiotherapy, sterilization of products, preservation of foodstuffs and gamma radiography require special care in the design and operation of equipment to avoid radiation injury to workers or to the public. Experience has shown that such technology is generally used safely, but on occasion controls have been circumvented and serious radiation accidents have ensued. 2. Reviews of radiation exposures from accidents have been presented in previous UNSCEAR reports. The last report containing an exclusive chapter on exposures from accidents was the UNSCEAR 1993 Report [U6]. 3. This annex is aimed at providing a sound basis for conclusions regarding the number of significant radiation accidents that have occurred, the corresponding levels of radiation exposures and numbers of deaths and injuries, and the general trends for various practices. Its conclusions are to be seen in the context of the Committee's overall evaluations of the levels and effects of exposure to ionizing radiation. 4. The Committee's evaluations of public, occupational and medical diagnostic exposures are mostly concerned with chronic exposures of …

sources and effects of ionizing radiation

The distribution of iodine in the earth's crust

[sup 129]I/[sup 127]I ratios measured in meteoric water and epiphytes from the continental United States are higher than those measured in coastal seawater or surface freshwater and suggest long-range atmospheric transport of [sup 129]I from the main source for the earth's surface inventory, viz., nuclear fuel reprocessing facilities. The median ratio for 14 meteoric water samples is 2100 [times] 10[sup [minus]12], corresponding to a [sup 129]I concentration of 2.5 [times] 10[sup 7] atoms/L, whereas 9 epiphyte samples have a median ratio of 1800 [times] 10[sup [minus]12]. Calculated deposition rates of [sup 129]I in the continental United States reveal that a small but significant fraction of the atmospheric releases from the nuclear fuel reprocessing facilities at Sellafield, England, and Cap de La Hague, France, is deposited after distribution by long-range transport. The inferred dominant mode of transport is easterly, within the troposphere, mainly in the form of the organic gas methyl iodide.

Atmospheric Dispersal of 129Iodine from Nuclear Fuel Reprocessing Facilities

Methyl iodide (CH3I) plays an important role in the natural iodine cycle and participates in atmospheric ozone destruction. However, the main source of this compound in nature is still unclear. Here we report that a wide variety of bacteria including terrestrial and marine bacteria are capable of methylating the environmental level of iodide (0.1 μM). Of the strains tested, Rhizobium sp. strain MRCD 19 was chosen for further analysis, and it was found that the cell extract catalyzed the methylation of iodide with S-adenosyl-l-methionine as the methyl donor. These results strongly indicate that bacteria contribute to iodine transfer from the terrestrial and marine ecosystems into the atmosphere.

https://aem.asm.org/content/aem/67/6/2718.full.pdf

Bacteria mediate methylation of iodine in marine and terrestrial environments.

[1] A spatial survey of iodine and its long-lived isotope, 129I, in 40 rivers of the USA, Canada, and western Europe, reveals that the ratio of 129I/I is a sensitive indicator for the influence of nuclear fuel reprocessing facilities Rivers with point sources for 129I in their watersheds are drastically affected, while all rivers sampled show evidence for atmospherically transported 129I from the world's major nuclear fuel reprocessing facilities Varying mixtures of oceanic cyclic salt and soil-derived iodine account for the observed spatial variation in iodine concentrations A comparison of 129I concentrations in river and rainwater reveals concentration effects due to evapotranspiration

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2001WR000622

Y. Ohmomo

Papers

Iodine-129 and iodine-127 in environmental samples collected from Tokaimura/Ibaraki, Japan