Menstrual cups have gained popularity with several brands and technoeconomic analyses suggesting use for up to 10 years. However, there is a lack of long-term biostability data for menstrual cups in current literature. In this work, we subjected medical-grade and food-grade silicone samples to a 1 M hydrochloric (HCl) acidic solution to determine whether environmental pH influences degradation behavior. Our findings demonstrate that food grade silicone is more susceptible to hydrolytic degradation (8.94 ± 0.41% mass loss) than medical grade silicone (0.15 ± 0.20% mass loss). Medical grade silicone also showed some mass loss, albeit a very small amount (0.69 ± 0.07%), after ten months in a vaginal fluid simulant. In follow-up studies, food grade silicone was immersed in 1M HCl and 1 M sodium hydroxide (NaOH) for 28 days to compare degradation under chemically accelerated conditions. Gravimetric analysis revealed significantly greater mass loss under acidic conditions (maximum 8.06 ± 0.97%) compared to basic conditions (maximum 2.76 ± 0.20%). These results validate earlier accelerated degradation testing and indicate that silicone is more susceptible to acid-catalyzed hydrolysis. Future studies will expand this workflow to better emulate real world menstrual cup use by using commercially available devices.
