What do you know about piecing?

i am so curious about putting a bar in my nipple i work in attics and under houses sometimes on my chest . would this cause a hazard or infection ? and my nipple goes in most the time and comes out when played with or when it fells like it its sensitive how do you think or know from experience that this will affect a nipple piercing . and does a bar make it more sensitive to touch , or shirt rubbing ? stuff like that