I. Understanding Radioactivity
Customs authorities at passenger checkpoints have repeatedly intercepted "energy stones" or "health stones" with excessive radioactivity, leading to their rejection or return. Marketed as jewelry, these highly radioactive products not only fail to provide health benefits but also expose wearers to dangerous levels of ionizing radiation, a known carcinogen. But what exactly is radioactivity?
Radioactive "energy stones" exceeding safety limits
Radioactivity refers to the process by which unstable atomic nuclei spontaneously emit α, β, or γ rays while transforming into other elements. This process is accompanied by the release of radiation, which usually carries high energy. When such radiation passes through matter, including human tissue, it can strip electrons from atoms or molecules, turning such neutral atoms or molecules into positively charged ions. Hence, it is called ionizing radiation. The harm caused by ionizing radiation lies in its ability to damage biological macromolecules like DNA within our cells, disrupt cellular functions, and even trigger cell death or cancer. In contrast, non-ionizing radiation carries lower energy, which is insufficient to remove electrons. Its interaction with matter is limited to inducing atomic or molecular vibration or rotation (manifested as heat) or exciting electrons to higher energy levels (leading to light emission). This category encompasses all electromagnetic radiation, such as visible light, infrared, microwaves, and radio waves. Everyday exposures like mobile signals or microwave radiation fall into this category and pose minimal health risks. Thus, public health concerns focus primarily on ionizing radiation, rather than electromagnetic radiation.
Naturally, the living environment of us contains multiple sources of radioactivity that cannot be completely eliminated or shielded. When high-energy particle streams from outer space collide with the atmosphere of our planet, they produce electromagnetic radiation. The Earth's crust contains naturally occurring radioactive elements such as uranium-238, thorium-232 series, and potassium-40. These elements are widely distributed in rocks, soil, and building materials (including granite, concrete, and bricks), and they generate ionizing radiation during decay. Similarly, Radon in the air decays and produces ionizing radiation, too. It is impossible to completely shield against cosmic rays from space, nor can we live in a vacuum or completely isolate ourselves from the Earth's rocks and soil. Radioactive decay is a spontaneous and natural process largely unaffected by external factors such as temperature or pressure. As long as radionuclides exist, decay will continue to occur, and ionizing radiation will persist. The inherent radiation level present in the environment, in the absence of specific artificial radiation sources, is referred to as the background radiation level. This level fluctuates within a certain range due to factors such as geographical location (altitude, geology), living environment (building materials, ventilation), and meteorological conditions (e.g., atmospheric pressure and rainfall will affect radon release). However, it never drops to zero.
II. Radioactivity in Mineral Products
Certain minerals, including rare-earth ores, bauxite, niobium and tantalum ores, zircon sand, and copper ore, naturally contain associated radionuclides like uranium, thorium, and radium. Artificial radionuclides may also be introduced during mining or processing, leading to abnormal radioactivity of mineral products. If radioactive content exceeds limits, workers, surrounding residents, and consumers may be exposed to ionizing radiation during mining, transport, storage, processing, or end use. Poor management could spread radioactive materials, contaminating soil, water, and air.
According to long-term Customs inspection and regulatory statistics, mineral products that are prone to abnormal radioactivity include: uranium and thorium ores, which typically contain high concentrations of radionuclides; niobium and tantalum ores, which often exhibit excessive γ radiation dose rates due to associated elements such as uranium and thorium; rare-earth ores, which frequently contain associated radioactive elements like uranium and thorium; zircon sand, which may carry radionuclides from the uranium decay chain (e.g., Ra-226); as well as copper and zinc ores, which are commonly associated with uranium deposits.
Monazite
Niobium and Tantalum ores
III. Radioactivity Inspection Standards for Mineral Products
Under the Law of the People's Republic of China on Import and Export Commodity Inspection and the Regulations for the Implementation of the Law of the People's Republic of China on Import and Export Commodity Inspection, Customs authorities are mandated to inspect imported mineral products for radioactivity to prevent shipments that exceed safety thresholds from entering the country. Previously, radioactivity inspections on imported mineral products and compliance determinations were performed according to the Rules for the Inspection of Radioactivity of Imported Minerals (SN/T 1537–2023).
Although advanced radiation detection equipment targeting at mineral products has seen increasing use in mining, transport, and processing in recent years, such technologies had not been fully incorporated into import inspection procedures. To improve inspection efficiency and accelerate clearance, the General Administration of Customs organized a panel of experts to revise the standard of the above-mentioned Rules for the Inspection of Radioactivity of Imported Minerals (SN/T 1537–2023). The updated protocol officially came into effect on August 1, 2025.
IV. Key Updates
1. Adoption of Fixed γ-Ray Detection Equipment for Inspection
Portal-type γ-ray detection systems are already widely deployed for cargo and passenger screening at ports, mainly including radiationportal monitoring system for trains, radiationportal monitoring system for vehicles, radiation portal monitoring system for individuals, and radiation portal monitoring system for luggage. These systems align with mature national standards and calibration protocols and use well-established radiation detection methodologies. In practice, there are numerous cases where containerized mineral shipments have been screened using radiation portal monitoring system for vehicles.
In addition to portal-type γ-ray detection systems, other fixed equipment such as conveyor belt-mounted radiation detection system and grab-mounted radiation detection system are also increasingly used to inspect imported mineral products for radiation level. Developments are also underway for robot-deployed portable γ-ray detectors. The use of fixed γ-ray detection systems requires initial measurement of the background radiation level, which must be conducted in an environment free of radioactive interference. The alarm threshold of fixed γ-ray detection systems is set at three times the background radiation level.
The updated rules mark a significant shift from earlier methods that relied solely on portable γ-ray detectors by integrating new technological equipment that is widely used and proven in practice, and are expected to greatly enhance on-site inspection efficiency, simplify clearance processes, and contribute to a more favorable business environment.
Portal-type γ-ray Detection System
Conveyor Belt-based γ-ray Detection System
2. Adjustment of Mobile γ-Ray Detection Equipment for Inspection
(1) Containerized Mineral Shipments
Three inspection methods are now available for containerized mineral products: external inspection, open-door inspection, or full-unloading inspection. The method used may be adapted to on-site conditions.
For external inspection, lots of up to 500 metric tons form one inspection unit and are scanned for radioactivity. During the scanning process, if exceeded radiation is detected, one to two containers will be selected for measurement on all four sides. Readings of radiation, concerning the inspected minerals, between three times the background radiation level and the alarm threshold trigger open-door inspection or full-unloading inspection. Results exceeding the alarm threshold require nuclide analysis. This approach eliminates the need for the earlier, cumbersome practice of scanning every container on all four sides during the radiation detection process.
Open-door inspection requires all containers to be opened. Lots of up to 500 metric tons form one inspection unit and are scanned for radioactivity, with at least five random sampling points, representative of the entire batch, selected for 10-second readings each during the scanning process. Results exceeding the alarm threshold require nuclide analysis. This approach eliminates the earlier, cumbersome practice of scanning the mineral cargo inside each and every container during the radiation detection process.
Certain containerized minerals, such as iron and manganese ore, require full-unloading inspection per Customs inspection rules. To reduce the workload from external inspection and open-door inspection and support integrated supervision, the full-unloading inspection method has been formalized. Once unloaded, the radiation inspection of mineral products within the containers, in lots not exceeding 500 tons, shall be conducted in a manner substantially consistent with the inspection method prescribed for bulk mineral shipments.
(2) Bulk Mineral Shipments
Significant adjustments have been made to the radiation inspection protocol for bulk maritime shipments of mineral products. The general requirement stipulates that inspections shall be conducted at a minimum of four stages: upon commencement of unloading, when approximately one-third and two-thirds of the total cargo have been unloaded, and upon completion of unloading. For mineral shipments exceeding 1,500 metric tons, measurements at 500-ton intervals are mandated only under the conditions that there are explicit directives or reliable intelligence indicating a high risk of radioactivity, or on-site inspection reveals radiation levels of the cargo exceeding the alarm threshold. The calibrated rules to inspection intervals are the result of a technical review and risk assessment based on three years of radiation inspection data targeting mineral products.
3. Updated Alarm Thresholds for Mobile γ-Ray Detection Equipment
(1) External Inspection
For external scans, the alarm threshold has now been set to three times the background radiation level, aligning it with the standard already used for fixed γ-ray detection systems.
(2) Open-door Inspection and Full-unloading Inspection
The earlier rules cited GB 20664 (Limitation concentration of natural radioactivity in non-ferrous metal ores and concentrates products) for non-ferrous metal ores such as copper, lead, and zinc, but failed to specify a clear alarm threshold, reducing its on-site operational usefulness. The revised rules resolve this ambiguity by mandating a defined trigger value - A γ-ray dose equivalent rate (including background radiation level) of 0.4 µSv/h shall now serve as the alarm threshold during inspections using mobile γ-ray detection systems targeting at non-ferrous metal ores such as copper, lead, and zinc.
4. Additional Revisions
For packaged mineral products, the new guidelines emphasize that mobile γ-ray detection systems must be placed flush against the packaging surface during radiation inspection. When necessary, inspectors are permitted to open the packaging for direct measurement.
For other mineral products subject to specific radioactivity limits, alarm thresholds must be configured according to the corresponding official standards as required by the updated rules. Result evaluations shall also comply with these requirements subject to such specific radioactivity limits.
A new section has been added to Appendix A of the updated rules, outlining detailed methods for the collection and preparation of samples intended for nuclide analysis of mineral products.
