Don't pick up, take apart or sell metal parts of unknown origin, and stay away from anything with a trefoil warning sign

Cost

Free. If you see an unfamiliar metal cylinder, a lead canister, or a part removed from equipment, go around it; don't pick it up, take it apart or put it in your pocket.

What you get

The National Nuclear Safety Administration (国家核安全局) explains that a radioactive source is a solid radioactive material permanently sealed in a container or tightly clad. Industrial level gauges, flaw detectors and hospital gamma knives all use this kind. Without shielding, contact with a Class III source for a few hours can cause permanent damage, and days to weeks can be fatal. X-rays can't be seen with the naked eye, and gamma rays are electromagnetic waves like them. Protection against external exposure rests on three things: shorten the time, increase the distance, add shielding. Gamma rays penetrate strongly and can be stopped only by a thick concrete wall or lead. As of 2025, China had about 178,000 (17.8万) radioactive sources in use and 355,000 (35.5万) radiation devices (units or sets). The annual rate of radiation accidents involving sources has stayed below 1 per 10,000 sources. The grading works like this. Loss, theft or loss of control of a Class I or Class II source makes a major radiation accident. Class III is a serious radiation accident. Loss or theft of a Class IV or Class V source, or exposure of people above the annual dose limit, is a general radiation accident. An official case: in June 2020, at the ironworks of Ningxia Steel Group, gamma-ray flaw detection was being done on a blast furnace pipeline renovation project. A Class II iridium-192 source exposed three workers. Chen had acute radiation skin injury of grade III on the left hand. Liu had grade IV on the left thumb and index finger and grade III on the middle, ring and little fingers. Fan had grade I-II on the left hand. All three received doses seriously above the dose limits in national standards, and the two responsible companies had their radiation safety licenses revoked and were fined 70,000 CNY (7万). An international case: in 1987 in Goiania, Brazil, a teletherapy machine from an abandoned clinic was dismantled, a cesium-137 source of 50.8 TBq was taken out, and the sealed capsule holding the source was broken. About 112,000 people were monitored. Of these, 249 were contaminated inside or outside the body. Of those 249, 129 were moderately to severely contaminated and 50 needed close medical monitoring. In the end 4 died (national / international).

Notes

If you do come across one: stay away, remember the location, don't move it, and call 110. The regulations require reporting to the ecological environment authority, the public security authority and the health authority. The only protection an ordinary person can manage is staying away and spending little time near it; a pocket or a plastic bag cannot stop gamma rays. X-ray machines and CT scanners produce radiation by passing electricity through an X-ray tube and contain no radioactive source themselves; this follows from how radiation devices work. Accelerators are different: after shutdown there is still induced radioactivity in the structural materials and the air of the machine room. What is really dangerous is the sealed radioactive source inside equipment; gamma knives, gamma flaw detectors and level gauges all contain sources. The Goiania accident happened because someone took a machine apart and took the source out. So don't count on recognizing a radioactive source; never take apart, sell or take home a piece of equipment of unknown origin. Cases of people unknowingly picking up a source have also happened in China. In May 2014, in a chemical park in Nanjing, an iridium-192 source was lost during flaw detection work at a factory. A warehouse keeper picked it up on his rounds and put it in his work-clothes pocket. He was later diagnosed with mild acute radiation sickness and acute radiation skin injury of the right leg, was treated in the hospital for a year, and several years later still walked with two crutches. Two other workers said they had seen it, and one of them, on the way to work, took it for a necklace, picked it up, looked at it and threw it away. The company that lost the source was Tianjin Hongdi Engineering Inspection Development Co., Ltd. (天津宏迪工程检测发展有限公司). No official accident bulletin on this was found. The picker's injuries are taken from a follow-up paper published by doctors at the Jiangsu Provincial CDC; the part where it was picked up and thrown away rests only on a China Environment News (《中国环境报》) reporter's account. People who work in scrap collection, dismantling, hardware and construction sites are more likely to run into one; this is inferred from the Goiania and Nanjing accidents. If you see a cordoned area marked with the trefoil sign on a site, go around it. What is meant here is a source that has gone out of control; a nuclear power plant leak is a different kind of accident and is not covered here. The beneficiary is mainly you and the family members at the scene with you.

Evidence grade

A : Specific numbers from meta-analyses, large cohorts or randomized trials; for law and policy, the statute or official text.

Sources

1. Ministry of Ecology and Environment (2025). 2024 Bulletin on the State of the Ecology and Environment in China [in Chinese]. https://www.mee.gov.cn/ywgz/sthjjcgl/hjzljcypj/202506/t20250605_1120773.shtml
2. National Nuclear Safety Administration (2026). Achievements of China's Nuclear and Radiation Safety Supervision in 2025 [in Chinese]. https://nnsa.mee.gov.cn/tpxw/202601/t20260107_1140062.html
3. Ministry of Ecology and Environment (2021). Circular on the Handling of a Radiation Accident Caused by Illegal Gamma-Ray Flaw Detection Operations [in Chinese]. https://www.mee.gov.cn/xxgk2018/xxgk/xxgk06/202101/t20210121_818216.html
4. State Council (2019). Regulations on the Safety and Protection of Radioactive Isotopes and Radiation-Emitting Devices [in Chinese] (revised 2019, Articles 34, 42 and 68). https://www.mee.gov.cn/ywgz/fgbz/xzfg/201909/t20190918_734315.shtml
5. Ministry of Environmental Protection (2009). Notice on Establishing a System for Graded Handling and Reporting of Radiation Accidents Involving Radioactive Isotopes and Radiation-Emitting Devices [in Chinese] (radiation accident grading standards). https://www.mee.gov.cn/gkml/zj/wj/200910/t20091022_172414.htm
6. National Nuclear Safety Administration. [Nuclear Technology Applications] What Is a Radioactive Source? [in Chinese]: "A radioactive source is radioactive material, other than material in the nuclear fuel cycle of research reactors and power reactors, that is permanently sealed in a container or has a tight cladding and is in solid form" "Level gauges, gamma flaw detectors and the like all use sealed sources". For a Category III radioactive source, "without protection, a few hours of contact with this type of source can cause permanent injury to a person, and contact for a few days to a few weeks can also cause death". https://nnsa.mee.gov.cn/ztzl/haqshmhsh/hyfsaqkp/kptw/202406/t20240624_1076670.html
7. National Nuclear Safety Administration (republished from the Shandong Nuclear and Radiation Division). Popular Science on Nuclear and Radiation [in Chinese]: "cesium-137 used in industrial level gauges, iridium-192 used in flaw detectors, and cobalt-60 used in hospital gamma knives, among others". https://nnsa.mee.gov.cn/ztzl/haqshmhsh/hyfsaqkp/kptw/202406/t20240624_1076991.html
8. National Nuclear Safety Administration. The Wonderful Nuclear Technology (16): Radiation Protection and Management [in Chinese]: "There are generally three basic protective measures against external exposure: time, distance and shielding". https://nnsa.mee.gov.cn/ztzl/haqshmhsh/hyfsaqkp/kptw/202406/t20240624_1076933.html
9. National Nuclear Safety Administration. [Radiation Protection] What Types of Radiation Are There? [in Chinese]: "Gamma rays, like X-rays, are electromagnetic waves" "They have strong penetrating power and need thick material to shield them, so protection mostly uses thick concrete walls or materials such as lead". https://nnsa.mee.gov.cn/ztzl/haqshmhsh/hyfsaqkp/kptw/202406/t20240624_1076595.html
10. National Nuclear Safety Administration. Nuclear Knowledge in Daily Life: X-Ray Security Screening Machines [in Chinese]: "X-rays, also called Roentgen rays, are rays that cannot be seen by the naked eye". https://nnsa.mee.gov.cn/ztzl/haqshmhsh/hyfsaqkp/kptw/202406/t20240624_1076874.html
11. Hunan Institute of Geology (2023). Radiation-Emitting Devices in Nuclear Technology Applications [in Chinese] (excerpted from the Guidebook on Comprehensive Knowledge of Nuclear Safety): "The core part of an X-ray machine is the X-ray tube" "Delayed radiation persists after an accelerator is shut down" "After an accelerator is shut down, the effect of induced radioactivity must be considered when entering the accelerator hall or target hall". http://hnsdzy.hunan.gov.cn/dzy/c101626/c101627/c101633/202304/t20230411_29311495.html
12. International Atomic Energy Agency (1988). The Radiological Accident in Goiânia. IAEA, Vienna. https://www-pub.iaea.org/MTCD/Publications/PDF/Pub815_web.pdf
13. Wang Fuxu, Wang Jin, Yu Ningle, et al. (2019). Medical Follow-Up Observation of Persons Exposed in the Nanjing "5.7" Radioactive Source Loss Accident [in Chinese]. Chinese Journal of Radiological Medicine and Protection, 39(11), 859-863. https://doi.org/10.3760/cma.j.issn.0254-5098.2019.11.011
14. China Environment News (2014-05-15). 48 Hours of a Lost Radioactive Source [in Chinese] (Xu Xiaoyan, Shao Yi, Chu Fangqiao, Tang Jingru). http://nnsa.mee.gov.cn/ztzl/haqshmhsh/hjbzl/202406/P020240624472937009953.pdf (web archive copy https://web.archive.org/web/20261005044102/http://nnsa.mee.gov.cn/ztzl/haqshmhsh/hjbzl/202406/P020240624472937009953.pdf)

Translated from the Chinese original. Original book, section 1, tip 36. This section is about health and medicines. It is general information, not a substitute for a doctor’s diagnosis or prescription. Content may be out of date and rules differ by place. When you actually deal with an agency, a doctor or a court, follow what local officials, doctors and lawyers tell you. Disclaimer