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The origin of radioactive Cobalt-60 found in west Delhi's Mayapuri, which led to the death of one person, has been traced to Delhi University's Chemistry Department where it was lying unused since the last 25 years.
The Cobalt-60 was in a "Gamma Irradiator", which was bought in 1968 from Canada and was not in use since 1985, police said on Wednesday adding it was bought by scrap dealers in Mayapuri through an auction in February this year. "We have traced the radioactive material to Delhi University's Chemistry Department. One of the equipment the scrap dealers bought was Gamma Irradiator," Joint Commissioner of Police (Southern Range) Ajay Kashyap told PTI. The scrap dealers dismantled the equipment and in the process, the lead covering on it was pealed off leading to radiation exposure, Kashyap said.
"The equipment was in use till 1985 and after that it was lying in a room unused. In February, University committee decided to sell it and the Mayapuri scrap dealers bought it through auction," he said. He said the four workers who are admitted to city hospitals were shown photographs of the equipment and one of them identified it. Panic gripped Mayapuri in the first week of April when 11 people were admitted to hospitals after they were exposed to radiation. A worker in the scrap shop from where the Cobalt 60 was discovered has died due to exposure to radiation.
Gamma irradiators are used for radiation processing application. At one stage of investigations, it was suspected that the scrap material came from abroad. Some reports even suggested that the scrap originated from medical waste from a city hospital. Eleven sources of radiation were detected in the Mayapuri scrap market where Cobalt-60 was recovered this month.
Cobalt-60 is a radioactive isotope of cobalt, which is a hard, lustrous, grey metal. It is used in cancer therapy machines and other medical equipment. The radiation exposure came to light when Deepak Jain, a scrap dealer, and four of his workers were admitted to city hospitals. Experts from Department of Atomic Energy and Bhabha Atomic Research Centre have scanned all the 800 shops in the scrap market and said that the locality was radiation-free.