Awareness of the growing interest in the use of mentrual cups in 2002 began a cooperative effort by APT and the Endometriosis Research Center to question the safety of these products. A particular focus for these concerns was the absence of product labeling for the possible increased risk of endometriosis in association with the use of mentrual cups. An alternate description of mentrual cups is "menstrual retention devices." As described in detail in the 2003 FDA Citizen's Petition ( https://wayback.archive-it.org/20441/20230616000609/http://www.mum.org/fdacups1.htm ) , a rubber barrier over the cervix produces a closed system in which menstrual fluid and the endometrial cells it contains can be compressed and increase backflow of mentrual fluid into the peritoneum - the chief site where endometriosis occurs. The cups being marketed in 2003 were not required to do new safety research because they were pre-approved based on products marketed from the 1930s to the 1950s. I