India meets with the founder and director of Chem Trust, Elizabeth Salter Green, and Shruthi Mahalingaiah Assistant who is a Professor of Environmental Reproductive and Women's Health at the Harvard T H Chan School of Public Health, to discuss the implication of modern day synthetic chemicals on the menstrual cycle and the natural world.

Credits: Presented by India Rakusen. Producer: Ellie Sans. Assistant Producer: Jorja McAndrew. Executive Producer: Suzy Grant. Original music composed and performed by Rebekah Reid. Sound Design by Charlie Brandon-King.

Special thanks to all contributors and audio diarists.

A Listen production for BBC Radio 4 and BBC Sounds.