There are many other synonyms in Hindi for that word too. Ya, I would certainly not use it in front of my parent & think of an another word, neither in a formal official setting but IRI is none of them. But it does not mean that it is a cuss word.
There may be many words in your native language too which you may not be comfortable to speak with your parents or with your boss, but you use it often in regualar talks. Does that mean you are uncivilized. Definitely not. I have not used a slang, it is just a normal word & I stand by my words.