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

https://www.amjmed.com/article/0002-9343(94)90321-2/pdf

Long-term impact of initial surgical and medical therapy on papillary and follicular thyroid cancer.

Papillary and follicular thyroid cancer, together referred to as differentiated thyroid cancer (DTC), is usually curable when discovered at an early stage. Its management, however, is often a challenge because there have been no prospective randomized trials of treatment and none are likely to be done, given its typically prolonged course and relative infrequency. Instead, clinicians rely on large patient cohort studies in which therapy has not been randomized, leading to some disagreement about management. Nonetheless, thyroid cancer mortality rates have fallen significantly (20%, P , 0.05) in the United States between 1973 and 1996 (1), almost certainly due to early diagnosis and effective treatment of DTC, which comprises 90% of thyroid cancers and 70% of the thyroid cancer deaths (2). The decline in mortality, however, occurred only in women (1), perhaps because they undergo routine medical examinations more than men, in whom thyroid cancer is typically discovered at an older age (1). DTC is more likely to be completely resected and ablated with iodine-131 (I), an approach that has become more popular in the past several decades, when discovered at an early stage (3, 4). Much of the following discussion refers to treatment of DTC because the approach to treatment of papillary and follicular cancer is usually very similar.

Current Approaches to Primary Therapy for Papillary and Follicular Thyroid Cancer

The thyroid gland of children is especially vulnerable to the carcinogenic action of ionizing radiation. To provide insights into various modifying influences on risk, seven major studies with organ doses to individual subjects were evaluated. Five cohort studies (atomic bomb survivors, children treated for tinea capitis, two studies of children irradiated for enlarged tonsils, and infants irradiated for an enlarged thymus gland) and two case-control studies (patients with cervical cancer and childhood cancer) were studied. The combined studies include almost 120,000 people (approximately 58,000 exposed to a wide range of doses and 61,000 nonexposed subjects), nearly 700 thyroid cancers and 3,000,000 person years of follow-up. For persons exposed to radiation before age 15 years, linearity best described the dose response, even down to 0.10 Gy. At the highest doses (> 10 Gy), associated with cancer therapy, there appeared to be a decrease or leveling of risk. For childhood exposures, the pooled excess relative risk per Gy (ERR/Gy) was 7.7 (95% CI = 2.1, 28.7) and the excess absolute risk per 10(4) PY Gy (EAR/10(4) PY Gy) was 4.4 (95% CI = 1.9, 10.1). The attributable risk percent (AR%) at 1 Gy was 88%. However, these summary estimates were affected strongly by age at exposure even within this limited age range. The ERR was greater (P = 0.07) for females than males, but the findings from the individual studies were not consistent. The EAR was higher among women, reflecting their higher rate of naturally occurring thyroid cancer. The distribution of ERR over time followed neither a simple multiplicative nor an additive pattern in relation to background occurrence. Only two cases were seen within 5 years of exposure. The ERR began to decline about 30 years after exposure but was still elevated at 40 years. Risk also decreased significantly with increasing age at exposure, with little risk apparent after age 20 years. Based on limited data, there was a suggestion that spreading dose over time (from a few days to > 1 year) may lower risk, possibly due to the opportunity for cellular repair mechanisms to operate. The thyroid gland in children has one of the highest risk coefficients of any organ and is the only tissue with convincing evidence for risk about 1.10 Gy.

Thyroid Cancer after Exposure to External Radiation: A Pooled Analysis of Seven Studies

We have analyzed the course of papillary thyroid carcinoma in 269 patients managed at the University of Chicago, with an average follow-up period of 12 yr from the time of diagnosis. Patients were categorized by clinical class; I, with intrathyroidal disease; II, with cervical nodal metastases; III, with extrathyroidal invasion; and IV, with distant metastases. Half of the patients had a history of thyroid enlargement known, on the average, for over 3 yr. In 15% of patients given thyroid hormone, the mass decreased in size. The peak incidence of cancer was when subjects were between 20–40 yr of age. Tumors averaged 2.4 cm in size; 21.6% had tumor capsule invasion, and 46% of patients had multifocal tumors. Sixty-six percent of the patients had near-total or total thyroidectomy. The overall incidence of postoperative hypoparathyroidism was 8.4%, but the incidence was zero in 83 near-total or total thyroidectomies carried out by 1 surgeon. Twenty-five percent of the patients had continuing or recurrent dise...

Natural history, treatment, and course of papillary thyroid carcinoma.

DECREASED maternal immune responsiveness during pregnancy may partly explain the survival of the fetus as an allograft. It may also account for changes in disease activity and antibody production i...

Decreased levels of helper T cells: a possible cause of immunodeficiency in pregnancy.

https://www.amjmed.com/article/0002-9343(83)91077-X/pdf

Retrospective and prospective study of radiation-induced thyroid disease

We compared the utility of lower (30 mCi) and higher (50 to 60 mCi) doses of 131I used to ablate residual thyroid tissue after thyroidectomy for carcinoma. Whole body scans were done using 1 mCi 131I, 3 weeks after withdrawal of triiodothyronine. Patients had received ablation therapy within 3 days after scanning, and one or more subsequent scans were analyzed. Forty-eight patients were treated to ablate residual thyroid tissue that was presumed to be normal. Among 18 patients given the lower dose of 131I as outpatients, 15 had successful ablation and three needed a second administration; all 30 patients treated with the higher dose had successful ablation. Seventeen additional patients, presumed to have residual cancer, received 50 to 150 mCi; and six needed treatment. Although 1 dose of 50 to 60 mCi 131I provides more ablation, use of the usually effective 30-mCi dose for initial ablation is justified by the convenience of outpatient administration, the lower expense, and the lower whole-body radiation dose.

Comparison of 30- and 50-mCi Doses of Iodine-131 for Thyroid Ablation

We have evaluated the utility of isotope bone scans and skeletal survey X-rays in the periodic evaluation of patients known to have had thyroid carcinoma. Patient data were evaluated in 29 patients with known metastatic disease and 79 patients without known metastatic disease who were followed over a period of 3-12 years and who had coincident 131Iodide whole body scans, technetium pyrophosphate bone scans, chest X-rays, and skeletal surveys, at periodic intervals. The information gained for each patient, at a time when two or three of the major survey procedures were conducted coincidentally, was evaluated retrospectively for its impact on classification and management of the patients. Metastatic tumor was detected in most instances by 131I RAIU in the lungs or by chest X-rays. Six patients had proven bone metastasis. Four of these patients had positive 131Iodide RAIU in bones, and two were positive and two negative by pyrophosphate bone scan. Only one was positive by skeletal survey X-rays at the time metastases were first detected by bone scans. Nine of the patients with metastatic disease displayed abnormal bone scans, but six of these were determined to be false positives. Bone scans detected one poorly differentiated metastatic tumor which did not accumulate 131I. Bone scans were more sensitive than skeletal survey X-rays. Physical exam, chest X-ray, and I131 whole body scans detected all instances of metastatic carcinoma.(ABSTRACT TRUNCATED AT 250 WORDS)

Maureen Reilly

Papers

Decreased levels of helper T cells: a possible cause of immunodeficiency in pregnancy.

Retrospective and prospective study of radiation-induced thyroid disease

Comparison of 30- and 50-mCi Doses of Iodine-131 for Thyroid Ablation

Use of isotope bone scans and skeletal survey X-rays in the follow-up of patients with thyroid carcinoma