Members of staff from Nanjing Environmental Protection Bureau during the search for the missing ir-192, which was lost on May 7, in Nanjing, Jiangsu province. Provided to China Daily

Monitoring procedures for all medical and industrial sources of radioactivity will be strengthened by authorities in Jiangsu province.

The use of radioactive testing equipment will also be suspended in Nanjing, the provincial capital, in August after inspection equipment containing iridium-192 was lost for three days.

A bracelet-shaped loop containing the radioactive material, known as Ir-192, was mislaid by workmen during routine inspections at a construction site in Nanjing's Luhe district on May 7. Authorities said the workmen failed to observe safety procedures while packing equipment.

The loss prompted a major police search and led to a construction site cleaner being hospitalized.

The silvery-white metal is used widely in industrial radiography to check for flaws in metal welds and castings, and in medicine, especially during interior radiotherapy procedures.

The workmen, from Tianjin Hongdi Engineering Inspection Development Co, a division of oil refiner Sinopec, didn't notice the bracelet was missing until the evening of May 8, when they tried to use the equipment and found it was malfunctioning.

The bracelet was found on Saturday afternoon by Yu Jianjun, director of the Getang Community Office in Luhe, who was assisting police and environmental experts in the search. When he discovered the bracelet, which contained a soybean-sized piece of ir-192, Yu sealed it in a plastic box before rushing to show it to the experts. The bracelet was then sealed in a lead-lined container and taken away for disposal.

"I've never run so fast. I can't say I wasn't afraid, but the material had to be recovered ... someone had to do it," Yu said.

The bracelet had been discarded near the community office by a construction site cleaner called Wang, who found it as he was sweeping the floor of the construction company's welding workshop at 8 am on May 7.

Wang said he slipped the bracelet into his pocket because he thought it would make a good key chain, but during his lunch break three hours later, he decided he didn't want it and threw the object into his front yard.

However, after learning that the police were searching for a piece of radioactive material lost at the site, he became afraid, so he wrapped the bracelet in a plastic bag and threw it into bushes near his home at 5 am on May 10.

Wang was later diagnosed with acute, short-term radiation sickness and is now being treated at the Second Affiliated Hospital of Soochow University in Suzhou.