In Vitro Metal Leaching from Tampons Under Simulated Vaginal and Menstrual pH Conditions

Background : Approximately 100 million people worldwide use tampons to manage their menstruation. Tampons have been shown to contain toxic metals, which may contribute to cumulative exposure risk. It is unclear whether metals leach from tampons and the effect of changes in vaginal pH during menstruation. Objectives : To quantify in vitro metal leaching from tampons under physiologically relevant conditions. Methods : We assessed metal leaching from 22 tampons by saturating them in simulated vaginal (pH 4.2) and menstrual fluids (pH 7.4) for 8 hours at 37°C on a shaker. Extracted supernatants were analyzed for 15 metals by inductively coupled plasma triple quadrupole mass spectrometry. Metal leaching was compared across 14 brands and tampon characteristics: organic composition and absorbency. The leaching fraction—percentage of total metal content leached—was calculated using data reported by Shearston et al. (2024). Results : We found measurable amounts of 15 metals in leachates from vaginal fluid and 12 metals in menstrual fluid, including lead, arsenic, and cadmium. Most metals leached greater amounts in vaginal fluid compared to menstrual fluid, such as lead (mean: 40.3 ng, 95% CI around mean value: [6.94, 73.7] vs. 15.6 ng, [6.91, 24.3]). The highest average leaching fraction in vaginal fluid was copper (233%, [-87% to 553%]), and in menstrual fluid, nickel (53%, 35% to 70%]). Metal leaching varied by tampon characteristics. Discussion : Under simulated menstrual conditions, we found that tampons leach metals in both vaginal fluid and menstrual fluid. Since in vitro metal release does not equate to vaginal absorption or systemic exposure further investigations are required to inform the risk of metal exposure from tampon use.