This has reference to the Op-Ed article, “Lessons from Mayapuri” (May 1). The sequence of events relating to the theft of radioactive sources from industries over the past decade shows that there are serious lapses in internal as well as external security systems. Fortunately, no major damage was caused to the people or environment. It seems that no lessons were learnt from the previous incidents. The Mayapuri- Delhi University incident is a wake-up call. Stringent security measures must be adopted by every industry using radioactive sources. The users must be educated on the dangers of radioactive materials exposed to environment, accidentally or as a result of carelessness. The industries using radioactive materials have the responsibility to protect the environment.