The following article shows the presence of high lead levels in Indian spices and colours. I think similar levels or even higher levels may be present in the same items sold in India. I don't think rangOli powders are any exception to this. Therefore it is important that parents (in particular mothers) supervise their children (in particular young girls) in using the rangOli powders and spices.
http://www.time.com/time/health/article/0,8599,1971906,00.html?xid=rss-topstories
Informative and a must read for all parents.