Hi Barbara,
There is an informative article about nipple piercing and breastfeeding available on the LLL website at http://www.lalecheleague.org/llleaderweb/LV/LVJunJul99p64.html . The article is primarily about how piercing affects breastfeeding. It recommends removal of nipple jewelry once baby is breastfeeding directly, "Choking is a potential hazard for the baby whose mother does not remove nipple jewelry before breastfeeding. As the baby sucks, the jewelry could become loose and lodge in the throat. The baby's gums and tongue as well as the soft and hard palate could be injured by the jewelry."
This article does not directly address your concern about contamination from the rings while pumping. However, you may find it useful and it may give you some other sources to contact.
Sara Dodder Furr, MA, breastfeeding advocate and volunteer
Lincoln, Nebraska
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