Megastar Amitabh Bachchan feels the association of celebrities with social causes is a result of the responsibility that comes with their star status.

"A celebrity has a responsibility, but it also has a great brand marketing at its doorstep. It is expected then, for them to be associated with some cause that is of social and moral nature. And there is a genuine interest taken up by the stars of the popularity charts," Amitabh wrote on his blog bigb.bigadda.com.

"Some talk about it as must they should, or how else would attention be drawn to it from the masses. Some like to be quiet about it. Do their share of work and not allow it to become an exercise in public relations!!" he added.

The 69-year-old is attached to various social causes, one of them being polio eradication. Amitabh is Unicef's brand ambassador against polio.