GBZ 113-2002 Intervention levels and medical treatment principles for ionizing radiation accidents
Some standard content:
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National Occupational Health Standard of the People's Republic of China GBZ113-2002
Guideline on intervention levels and medical managementinthe event of radiological accident2002-04-08 Issued
Ministry of Health of the People's Republic of China
2002-06-01 Implementation
1 Scope
Normative references
Terms and definitions
Dose control of emergency exposure of workers
Intervention level of emergency protection measures for the public>
Principles of medical treatment of accidental exposure personnel
8 Control of radioactive contamination
Appendix A (Informative Appendix) Biological effects of ionizing radiationAppendix B (Informative Appendix) Benefits, risks and costs of emergency countermeasuresAppendix C (Informative Appendix) Basis for estimation of the condition of exposed persons in external exposure accidentsAppendix D (Informative Appendix) Decontamination agents for surface contamination of radionuclides and absorption-blocking and excretion-promoting drugs for internal contaminationForeword
This standard is formulated in accordance with the "Law of the People's Republic of China on the Prevention and Control of Occupational Diseases". In case of any inconsistency between the original standard GB966288 and this standard, this standard shall prevail. Chapters 5 and 6 of this standard are mandatory contents, and the rest are recommended contents. This standard is formulated in accordance with the national standard "Basic Standard for Radiation Health Protection" (GB4792-84) and with reference to the relevant recommendations of international organizations such as ICRP and IAEA. All types of nuclear facilities, various radionuclide production and application units, and all units that generate and apply radiation devices should adhere to the principles of "prevention first" and "safety first" and follow the principle of optimization, implement relevant laws and regulations, and avoid the occurrence of ionizing radiation accidents. Appendix A, Appendix B, Appendix C, and Appendix D of this standard are informative appendices. This standard is proposed and managed by the Ministry of Health.
The drafting units of this standard: Institute of Radiation Protection and Nuclear Safety Medicine, Chinese Center for Disease Control and Prevention, Beijing Institute of Radiation Medicine.
The main drafters of this standard: Zhang Ming, Guo Lisheng, Chang Shiqin, and Tan Shaozhi. The Ministry of Health is responsible for interpreting this standard.
Intervention level and medical treatment principles for ionizing radiation accidents 1 Scope
GBZ 113-2002
This standard specifies the dose control of emergency exposure of workers, the emergency protection countermeasures for the public, the medical treatment of exposed personnel and the protection principle requirements for reestablishing normal working order in the event of ionizing radiation accidents. This standard applies to the protection of workers and the public in the event of ionizing radiation accidents. 2 Normative references
The clauses in the following documents become the clauses of this standard through reference in this standard. For any dated referenced document, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, the parties to an agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For any undated referenced document, the latest version shall apply to this standard.
GB4792
Basic standard for radiological health protection
GBZ104wwW.bzxz.Net
GBZ106
Diagnostic standard for acute radiation sickness caused by external exposure
Diagnostic standard for radiation skin diseases
Diagnostic standard for internal radiation sickness
GBZ/T153 Guidelines for the use of potassium iodide in radioactive iodine contamination accidents 3 Terms and definitions
The following terms and definitions are used in this standard
Ionizing radiation accident
radiologicalaccidents
Abnormal events caused by the loss of control of ionizing radiation sources, which directly or indirectly cause harm to life, health or property. 3.2
Accidental exposure
accidentalexposure
A type of abnormal exposure refers to involuntary and unintentional exposure received in accident situations. 3.3
Emergency exposure
Emergency exposure
A type of abnormal exposure, which refers to the excessive exposure that is planned to be accepted at the time of or after an accident in order to rescue people in distress, prevent the situation from escalating, or other emergency situations. 3.4
External contamination of radionuclides
External contamination of radionuclides Radionuclides contaminate the body surface.
Internal contamination of radionuclides
Internal contamination of radionuclides refers to radionuclides in the body exceeding their natural presence. 3.6
Acute exposure
acute exposure
High doses of radiation received in a short period of time. Chronic exposure
Chronic exposure
Exposure for a long period of time continuously or intermittently at a low radiation level is also called continuous exposure. Half lethal dose halflethal dose
The dose required to kill 50% of the members of a group within a certain period of time, usually expressed as LDs0. interventionlevels
Intervention level
In radiation protection, certain nuclear radiation dose levels are predetermined. When this level is exceeded or expected to be exceeded, it is necessary to consider taking measures to intervene.
Large nuclear facility
TargenuclearinstalTation
Is a major nuclear facility, including: nuclear power plants (nuclear power plants, thermal power plants, nuclear steam and heating plants); other reactors (research reactors, experimental reactors, critical devices, etc.): nuclear fuel production, processing, manufacturing, storage and post-processing facilities; radioactive waste treatment and disposal facilities; other nuclear facilities that require strict supervision and management. 3.11
Stochastic effect
stochastic effect
Biological effect whose probability of occurrence (rather than severity) is related to the size of the dose. It is generally believed that there is no dose threshold for this effect. The main stochastic effects are genetic effects and carcinogenic effects. 3.12
non-stochastic effect
non-stochastic effect
Biological effect whose severity varies with dose (such as cataracts in the lens of the eye, benign skin lesions, etc.). This effect may have a dose threshold.
irradiation in uterus
Intrauterine irradiation
Irradiation received in the womb from the implantation of the fertilized egg to the birth of the newborn. 3.14
critical group
criticalgroup
Among the various exposed population groups involved in a given practice, the group of people expected to have the highest exposure level, the exposure they receive can be used to measure the upper limit of the individual dose generated by the practice. 4 General Principles
4.1 Principles of protection to be followed in intervention of ionizing radiation accidents 4.1.1 To avoid non-stochastic effects, protective measures must be taken to limit the individual's exposure dose to a dose threshold that can cause non-stochastic effects, see Appendix A (Informative Appendix). 4.1.2 The total incidence of stochastic effects should be limited to the lowest value that can be reasonably achieved. 4.1.3 When taking any protective countermeasure, the optimal judgment and balance should be made based on its benefits, risks and costs, see Appendix B (Informative Appendix). Avoid taking emergency measures that are not worth the cost and bring unnecessary losses to society. 4.2 The dose range of ionizing radiation accidents to the human body may be very large, and random effects or non-stochastic effects may occur. To evaluate non-stochastic effects, the most appropriate amount is the absorbed dose of organs or tissues, in Gy. It can be applied regardless of the type of ionizing radiation or absorption medium. To evaluate stochastic effects, the amount that represents the individual's risk is the effective dose of the whole body, in Sv. However, it is not suitable for high-dose exposure that may cause acute damage. 4.3 In the event of an ionizing radiation accident, it is necessary not only to evaluate the dose level of the exposed individual, but also to evaluate the total effect that causes harmful health in the population. The collective effective dose equivalent can be used to roughly estimate the incidence of random effects in the population. 4.4 The main problems faced by radiation protection and medical treatment in ionizing radiation accidents are external radiation (local radiation, whole body radiation), internal radiation, skin beta-ray damage, and various combined radiation and damage. 5 Dose control of emergency radiation of workers
5.1 Emergency irradiation must be carefully planned in advance and approved by the leaders of the unit and the person in charge of protection. Personnel participating in emergency response are full-time personnel who have received special training or are familiar with the situation, and are limited to once in their lifetime. 5.2 The exposure dose equivalent of emergency personnel in an emergency event shall not exceed the following levels. Whole body: 0.25SV;
Limbs: 1.0Sv:
Eye lens: 0.15Sv;
Other single organs or tissues: 0.50Sv. 5.3 In order to save lives or in extremely special circumstances, when it is necessary to accept a dose higher than that listed in Article 5.2, the superior competent department shall make a decision based on the biological effects of ionizing radiation listed in Appendix A of this article, weighing the pros and cons. 5.4 Emergency personnel should take safe and reliable protective measures when participating in rescue work. Minimize internal and external exposure and surface contamination as much as possible.
5.5 Anti-radiation drugs can be used in advance before accepting emergency irradiation. 5.6 Personnel exposed to emergency radiation should be given medical observation, and their exposure doses and observation results should be recorded in detail in their health records. 6 Intervention level for emergency protection measures for the public 6.1 In the event of a serious ionizing radiation accident, the recommended intervention level for emergency protection measures for the public is shown in Table 1. Table 1 Intervention levels for countermeasures to be taken by the public when a large amount of fission products and activation products are released in an accident at a large nuclear facility Recommended values Expected dose
mSv/mGy
Received and "
To the lungs
Main, other
Main device
According to the case officer
100-500
250-500
500-5000
General measures
Shelter, take iodine stearate
Unnecessary
Necessary
Must (pay special attention to the protection of pregnant women and
children)
Must, until evacuation
Unnecessary
Necessary
Must Must (pay special attention to the protection of pregnant women and children)
Must, until evacuation
a Other organs do not include gonads and eye lenses. b Expected dose units, mSv for the whole body and mGy for organs Severe measures
Unnecessary
Unnecessary
National competent authorities may consider evacuation after judging based on specific conditions
Unnecessary
Unnecessary
National competent authorities may consider evacuation after judging based on specific conditions
6.2 Accident situations vary greatly and it is impossible to recommend a universal intervention level that is applicable to all situations. It is appropriate to limit a dose range for different countermeasures (within this dose range, the protective personnel Ten practical preventive plans are proposed for specific conditions). If the dose is below the lower limit, it is not considered appropriate to take countermeasures; if the dose is above the upper limit, it is undoubtedly necessary to take countermeasures.
6.3 In the development stage of the accident, due to special work requirements, a small number of personnel (including non-radiation workers) need to stay at their posts and may be exposed to a certain dose of radiation. This can be controlled according to planned special exposure. The effective whole-body dose should not be greater than 100mSv in a single event and should not be greater than 250mSv in a lifetime. At the same time, the annual dose equivalent received by any organ or tissue shall not exceed: H<limit body ≤150mSv; Hr (H all other organs) ≤500mSv. 6.4 In the later stage of the accident, in order to resume normal life and work order. Some personnel (including non-radiation workers) may participate in activities such as decontamination of buildings and equipment or disposal of radioactive waste. They can be controlled according to occupational exposure to radiation work. The total internal and external exposure dose equivalent in the first year should not exceed 50mSv. 6.5 When a large nuclear facility accident occurs, it is necessary to restrict the circulation, sale or trade of radioactive contaminated items or food in domestic and foreign markets, so that the annual dose equivalent of individuals caused by the use or consumption of these items should not exceed 5mSv in the first year after the accident, and should be controlled at 1mSv per year thereafter. 6.6 The risk level of less than 10 per year can be accepted by any individual in the public. Therefore, when the annual dose equivalent of the key population group is less than 5mSv, no intervention measures can be taken. 6.7 In protection practice, special attention should be paid to the issue of radiation exposure of pregnant women and children, and their exposure dose levels should be reduced as much as possible.
6.8 The radiation injury reaction of fractionated irradiation is lighter than the injury of the same dose of irradiation at one time. Chronic exposure (or continuous exposure) over weeks or months is less dangerous than receiving the same dose of exposure in a short period of time. 6.9 Regardless of the size and severity of the accident, it will have a certain impact on society, and we must pay attention to the work after the accident. In accordance with the relevant national nuclear safety and radiation protection laws and regulations, necessary health evaluations should be conducted on the causes, technical treatments and consequences of the accident.
7 Principles of medical treatment of accidental exposure personnel
7.1 General principles
7.1.1 First of all, the source of harmful factors should be eliminated as soon as possible, and the exposed personnel of the accident should be evacuated from the scene and the degree of harm to the personnel should be checked. Active rescue measures should be taken and reports should be made to the superior department at the same time. 7.1.2 According to the nature of the accident, the different dose levels of exposure and the different courses of disease, corresponding countermeasures and treatment measures should be taken quickly. In the rescue, life-threatening trauma, bleeding and shock should be treated first, and anti-radiation drugs should be used for those who are estimated to have received a large dose of radiation.
7.1.3 For persons suspected of having body surface contamination, the body surface contamination should be monitored first, and decontamination should be carried out quickly to prevent the spread of contamination.
7.1.4 The persons exposed in the accident should be registered one by one and files should be established. In addition to timely diagnosis and treatment, follow-up observations should be carried out according to their exposure conditions and degree of injury, so as to timely discover possible long-term effects and achieve the purpose of early diagnosis and treatment.
7.2 Personnel exposed in external radiation accidents
7.2.1 Early dose estimation According to the initial symptoms of the exposed persons and the absolute number of peripheral blood lymphocytes, and referring to the estimated results of physical dose, a preliminary estimate of the disease condition can be made quickly, see Appendix C (Informative Appendix). If conditions permit, peripheral blood lymphocyte chromosome aberration analysis (applicable dose range is 0.25~5.0Gy) and lymphocyte micronucleus determination can be carried out for further biological dose estimation.
7.2.2 For those with an exposure dose of less than 0.1Gy, general medical examinations may be performed to determine whether treatment is required; for those with an exposure dose of more than 0.25Gy, symptomatic treatment should be given; for those with an exposure dose of more than 0.5Gy, hospitalization for observation and timely treatment should be given; for those with an exposure dose of more than 1Gy, hospitalization for close observation and treatment is required. 7.2.3 For patients with acute external radiation, comprehensive treatment should be adopted in accordance with GBZ104. 7.2.4 For patients with acute radiation skin damage, graded diagnosis and treatment should be carried out in accordance with GBZ106. 7.3 Personnel exposed in internal radiation accidents
7.3.1 Radioactive nuclides can enter the body through the respiratory tract, digestive tract, skin wounds and even intact skin, causing internal radiation damage.
7.3.2 Patients with internal radiation should be diagnosed and treated in accordance with GBZ96. 7.3.3 The determination of internal exposure can be based on the pollution history (nature of the accident, type, concentration, and route of entry of radionuclides at the accident site), analysis of biological samples (such as blood, urine, feces, and other contents), and radioactivity measurement of the whole body or target organs and clinical manifestations. The dose is estimated based on the type of radionuclides in the body, the amount of deposition in the organs, and the exposure time.
7.3.4 Medical treatment of radionuclides entering the human body a) Remove the radionuclides at the initial entry site as soon as possible. Including: thoroughly clean the body surface contamination to prevent the spread of pollutants. When inhalation is suspected, the nasal cavity should be wiped, gargled, and expectorated, and local vasoconstrictors should be used if necessary. When ingestion occurs, vomiting, gastric lavage, laxatives, and absorption-blocking drugs can be used. b) According to the type and amount of radionuclides entering the body, the corresponding drugs should be selected as soon as possible for excretion-promoting treatment, see Appendix D (Informative Appendix). When radioactive iodine enters the body, stable iodine should be taken within 6 hours; when xenon enters the body, a large amount of water should be consumed or fluids should be replenished.
7.3.5 Personnel exposed to radionuclides with more than 2 annual intake limits (ALI) should be subject to medical observation and appropriate treatment: Personnel with more than 20 ALIs are considered to have severe internal exposure and should be subject to long-term, strict medical observation and active treatment, with attention paid to long-term effects.
7.4 Personnel exposed in internal and external mixed exposure accidents
Medical treatment for internal and external mixed exposure can refer to Articles 7.2 and 7.3. When accompanied by surface trauma, repeated flushing with saline and chelating agents can be used. For contamination that is difficult to remove with saline and chelating agents, surgical resection can be considered. 8 Control of radioactive contamination
8.1When a contamination accident occurs, first control the contamination, protect the accident site, and block all possible ways of spreading the contamination, such as temporarily shutting down the ventilation system or controlling the spillage of liquids carrying radionuclides, or using objects to absorb or cover and seal to prevent the contamination from spreading again.
8.2 Isolate the contaminated area and prohibit irrelevant personnel and vehicles from entering and leaving the site at will. Use roadblocks or obvious lines to mark the boundary area of the contamination and its degree of contamination. To enter the clean area from the isolation area, you must pass through the buffer zone to ensure that the clean area is not contaminated by radioactivity.
8.3 Personal protective equipment must be worn when entering the contaminated area, and enter the contaminated area through the buffer zone. 8.3.1 People coming out of the contaminated area must undergo personal monitoring, and special attention must be paid to the hands, face, hair, and shoes, followed by the buttocks, knees, cuffs, etc.
8.3.2 Articles and equipment taken out of the contaminated area must be inspected and processed in the buffer zone to meet the decontamination standards before they can be brought into the clean area.
8.3.3 The monitoring results of contamination must be recorded and expressed as the average count rate value of a certain area. For example, the average count rate value over 1000cm2 is used for monitoring the floor, ceiling and wall surface, 300cm is used for tables, clothes, etc., 100cm2 is used for skin contamination measurement, and 30cm is used for the fingertips and palms that are most susceptible to contamination. 8.4 After any surface is contaminated by radioactivity, comprehensive decontamination measures should be taken in time to clean it to the background level as much as possible or control it according to the values listed in Table 2.
Table 2 Control level of radioactive material contaminated surface Contaminated surface
Hands, skin, underwear, work socks
Work clothes, gloves, work shoes
Equipment, ground, wall
aRadioactive material
Unit is Bg/cm2
βRadioactive material
aThe longer the contamination time, the more difficult it is to decontaminate. When hands and skin are contaminated, they should be cleaned promptly with a detergent that has high decontamination efficiency, is non-irritating to the skin, and does not promote absorption. For other surface contamination, appropriate measures should be taken to remove the contamination. For fixed contamination, the control level can be appropriately increased, but it shall not exceed 5 times the value listed in the table. b For β radioactive material contamination with a maximum energy of less than 0.3MeV, the control value of surface contamination can be 5 times the value listed in the table. c For low and medium-toxic radionuclides, the control level can be relaxed by 10 times. d Equipment and supplies, after careful cleaning, when the contamination level is not greater than one-fiftieth of the value listed in the table, can be used in general work after measurement and permission from the protection department.
8.5 When cleaning individuals, scrub carefully with soap, warm water and a soft brush. When cleaning and disinfecting, proceed in order, starting with lightly contaminated areas and then heavily contaminated areas to prevent cross contamination. Pay special attention to the hands, especially the nail grooves and finger gaps. If necessary, apply elastic adhesive plaster for 2 to 3 hours, remove the adhesive plaster and wash with water, which has a good effect on removing residual contamination. Or use special detergents, see Appendix D (Informative Appendix). Generally, a large amount of soap and water is used to wash the hair. Special attention should be paid to prevent soap foam from flowing into the eyes, ears, nose and mouth. Monitoring should be carried out before and after each washing and disinfection to compare the decontamination efficiency. Decontaminated wastewater must be collected and treated as appropriate after monitoring.
8.6 Although the surface of vehicles or equipment that have been seriously contaminated by radioactivity has reached the permitted level after decontamination, when inspecting and dismantling the internal structure, caution should still be exercised to prevent the spread of contamination inside the structure. Monitoring and control should be carried out. A.1 Non-random effects
Appendix A
(Informative Appendix)
Biological effects of ionizing radiation
A.1.1 Non-random effects can occur in any organ or tissue that is irradiated with a sufficiently large dose. Its severity varies with the dose, and there may be a dose threshold. In the event of an ionizing radiation accident, individuals may be exposed to acute radiation and experience non-stochastic effects. Common organs and tissues that experience non-stochastic effects include bone marrow, lungs, thyroid gland, eye lens, gonads and skin.
A.1.2 When normal people are exposed to radiation, if the dose is lower than the values listed in Table A.1 below, non-stochastic effects are not expected.
Table A.1 Upper limit of dose levels for major tissues and organs without non-stochastic effects Tissues or organs
Gonads
Eye lens
Thyroid gland
Non-stochastic effects
Infertility (permanent)
Erythema and hair loss
Cataract
Pneumonia (non-fatal injury)
Hypofunction, myxedema
Upper limit of dose level (Gy)
A.1.3 After a single whole-body external irradiation of the normal population with a small dose of radiation, early clinical symptoms mainly characterized by autonomic nervous system dysfunction will appear, which may disappear on their own within 1 to 2 days after exposure, as shown in Table A.2. Table A.2 Early clinical symptoms of human body after being exposed to small doses of radiation Exposure dose (Gy)
0.25-0.50
0.50-1.00
1.00-1.50
Clinical symptoms
No obvious change
No obvious change
Some people (about 2%) have mild symptoms: dizziness, fatigue, loss of appetite, sleep disorders, etc. A few people (about 5%) have mild symptoms: dizziness, fatigue, loss of appetite, insomnia, thirst, etc. Some people (about 550%) have nausea,
A few people may vomit
Hematological changes
Lymphoma The number of lymphocytes slightly decreased, then increased and gradually recovered. The number of white blood cells did not change significantly. The number of lymphocytes and white blood cells was slightly lower than the normal value. Some decreased by about 25%, but recovered to the normal level quickly. Lymphocytes, white blood cells, and platelets can be reduced to 25-50% before irradiation, and may be restored to the normal level within half a year. Lymphocytes and platelets can be reduced by more than 50%, and white blood cells can be reduced to 50%, which may be restored to the normal value. A.1.4 The skin has various effects after irradiation. The earliest effects observed are temporary erythema and temporary hair loss. With the increase of dose, permanent hair loss, dry or wet desquamation, skin discoloration, edema, blister formation, etc. occur. In severe cases, ulcers, necrosis, atrophy and fibrosis occur. The incidence, severity and duration of the effects depend on the irradiation conditions.
A.2 Stochastic effects
A.2.1 The severity of stochastic effects is independent of the dose received, but their incidence depends on the dose. There may be no value. The most important stochastic effects are the induction of cancer and various serious genetic diseases. A.2.2 The risk of fatal and non-fatal cancers recommended by the International Commission on Radiological Protection and the International Atomic Energy Agency for radiation protection is shown in Table A3.
3 Risk of fatal and non-fatal cancers (10-Sv-1) Table A.3
Tissues or organs
Gonads (first two generations)a
Red bone marrow
Thyroid
All other tissues
Fatal cancer
Non-fatal cancer
aGonads refer to the risk of genetic effects, which is 0.4 for individuals (first two generations) and 0.8 for the population (all offspring). A.2.3 The risk of exposure to ionizing radiation varies with the sex and age of the exposed individual. The estimated risk of fatal cancer in women is 1.5×10~Sv, while the risk of fatal cancer in men is 1.0×10Sv. For example, the possibility of fatal cancer in fetuses or young children is twice as high as the average (1.25×10Sv). Thyroid cancer in women is 2 to 3 times higher than that in men. It has been shown that the incidence of thyroid cancer is higher in people with low iodine intake. A.3 Intrauterine irradiation
A.3.1 The most concerning effects of intrauterine irradiation are microcephaly and severe intellectual disability. The risk of severe intellectual disability caused by irradiation between 8 and 15 weeks of pregnancy is 0.4Sv. No obvious threshold has been found so far: the risk is lower after 15 weeks of pregnancy and may be a threshold; no such risk has been found for exposure before 8 weeks of pregnancy. A.3.2 After the fetus is irradiated, the induction of fatal malignant tumors in childhood is also one of the consequences that should be paid attention to after fetal irradiation. Its risk is slightly higher than that of adults, that is, 2.3×10-Svl. A.3.3 There is no evidence that short-term exposure to less than 100mGy in early pregnancy (8 to 15 weeks of pregnancy) can produce teratogenic effects.
B.1 Sheltering
Appendix B
(Informative Appendix)
Benefits, risks and costs of emergency countermeasures
Personnel hiding indoors can reduce the external exposure dose from radioactive smoke clouds to 1/2 to 1/10. Closing doors, windows and ventilation systems can reduce the dose caused by inhaled radionuclides. Sheltering can also reduce the external exposure dose caused by radionuclides settled on the ground, which is generally expected to be reduced to 1/51/10. The above attenuation coefficient depends on the type of building and the location of the personnel.
This countermeasure is simple and effective. When the hiding time is short, its risks and costs are small; but if the time is long (more than 12 to 24 hours), it may cause social and medical problems. Another advantage is that the crowd is controlled during the hiding process, which is conducive to taking further countermeasures, such as dispersing the population. 2 Personal protection methods
When there is radioactive nuclide contamination in the air, simple methods can be used for respiratory protection, such as covering the mouth with a handkerchief, towel, paper, etc., which can reduce the dose caused by inhaled radionuclides to 1/10. The protective effect is related to the particle size, the characteristics of the protective material, and the leakage around the protective object (such as a mask). Daily clothing, including hats, headscarves, raincoats, gloves and boots, can be used for body surface protection.
The public takes simple personal protection measures, which generally do not cause harm and cost little. However, when performing respiratory protection, people with respiratory diseases or heart disease should pay attention to adverse effects, which cannot be ignored. B.3
Taking stable iodine
Potassium iodide or potassium iodate can reduce the entry of radioactive iodine isotopes into the thyroid gland. Taking 100 mg of iodine (equivalent to 130 mg KI or 170 mg KIO3) at a time can generally prevent the thyroid gland from absorbing radioactive iodine within 5 to 30 minutes, and the absorption of iodine returns to normal after about a week. The time of taking iodine has a significant impact on the protective effect. The best effect is achieved when the drug is administered before or immediately after the intake of radioactive iodine. Administration 6 hours after intake can reduce the thyroid dose by about 50%. Administration 12 hours after intake has little expected protective effect. Administration after 24 hours is basically ineffective. The risk of taking stable iodine is not great, and only a few people may have an allergic reaction. However, since medication has a significant time limit, and nuclear accidents are often time-sensitive, distributing drugs may be a difficult problem, especially when the number of people and scope involved are large. If necessary, it can be distributed to the public in advance for storage and use. For details, please refer to GBZ/T153.
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