NANJING - A Chinese man who picked up a missing radioactive object off the ground mistakenly thinking it was valuable is being treated in hospital, said local police on Monday.

The man surnamed Wang told police that he picked up an iron chain-like item at around 8 a.m. on Wednesday while cleaning in a yard of a construction company under China's oil refiner Sinopec in Nanjing, capital of Jiangsu Province.

He put the item into his upper pocket. Later that day at 11:30 a.m., he put the object in the yard of his house.

When police began a large-scale search operation for the radioactive object, Wang wrapped it up in a blue plastic bag and threw it into some grass near his home at 5 a.m. on Saturday.

The radioactive item was found on Saturday afternoon and put into a lead pot.

The iridium-192 radioactive object went missing on Wednesday when four workers with Tianjin Hongdi Engineering Test Development Co. Ltd. were carrying out tests at the construction company.

Hongdi reported the loss to police late on Thursday night, prompting the city government to start an emergency response plan.

Police detained four Hongdi workers on Saturday. They had violated regulations and storage rules, police said.

No other people have been found to be harmed by any radiation, according to police and health authorities.