Technetium-99m is the most used medical isotope in the world as a radioactive marker for diagnosing diseases. Getty Images A unit of the Institute for Energy and Nuclear Research (Ipen) in São Paulo recorded an incident with radioactive material involving two workers. The incident happened on May 29 and was confirmed on Thursday (11/6) night by the National Nuclear Energy Commission (CNEN). The Ipen building is on the campus of the University of São Paulo (USP). According to a note from CNEN, the episode involved the presence of traces of technetium-99 during the removal of biological sensors from an autoclave, equipment used in the production of radiopharmaceuticals, medicines used in diagnostic tests or therapeutically, for the treatment of tumors. Radioactive incident at Ipen: what is known about technesium and health risks The incident took place at the institute's Radiopharmacy Center, which develops and supplies a comprehensive line of essential radiopharmaceuticals for diagnostic imaging and oncological therapies, serving hospitals, clinics and research centers throughout the country. "The incident involved two workers — Occupationally Exposed Individuals (IOEs) — who were subjected to in vivo examinations (Full Body Counter)", states the CNEN note. "The detected counts were low and demonstrated that there was no internal contamination. Contamination was restricted to the controlled area of ​​the Institute's Radiopharmacy Center." Ipen supplies radiopharmaceuticals to 430 clinics and hospitals across the country, contributing to 2 million medical procedures annually, many of them related to the diagnosis and treatment of cancer patients. The internal occurrence report dealing with this incident was sent to the National Nuclear Security Authority (ANSN) for analysis. ANSN stated in a statement that Ipen's Radiopharmacy has current operating authorization. "As part of the regular supervision and regulatory monitoring activities of licensed facilities, a notification was issued with a deadline of June 18, 2026 to meet the formulated requirements", says the ASNS note. "The notification guarantees the installation the exercise of contradictory and broad defense, and any additional measures will depend on the technical analysis of the information and documents presented by Ipen." According to the Union of Workers in the Federal Public Service in the State of São Paulo (Sindsef-SP), the cases came to light after the union and the Association of Ipen Servers (Assipen) sent a request for official information about the occurrence and the measures adopted to the institute's management and CNEN. Now on g1 What is technetium-99? Technetium — chemical symbol Tc on the periodic table — is a silvery-gray radioactive metal. According to the American Environmental Protection Agency (EPA), technetium occurs naturally in very small quantities in the Earth's crust, but is mainly produced in laboratories. Technetium-99 is produced during the operation of nuclear reactors and is a byproduct of nuclear weapon explosions. Technetium-99m is a short-lived form of Tc-99 used as a medical diagnostic tool. It does not remain in the body or the environment for long. Technetium-99m is the most used medical isotope in the world as a radioactive marker for diagnosing diseases. The substance is injected into patients. Special cameras help form an image from the technetium present in the body. READ ALSO: Understand how the incident with radioactive material occurred at Ipen in SP