Microplastics have been found for the first time in human ovary follicular fluid, raising a new round of questions about the ubiquitous and toxic substances’ potential impact on women’s fertility.

The new peer-reviewed research published in Ecotoxicology and Environmental Safety checked for microplastics in the follicular fluid of 18 women undergoing assisted reproductive treatment at a fertility clinic in Salerno, Italy, and detected them in 14.

The findings represent a major step toward figuring out how and why microplastics impact women’s reproductive health, but are also “very alarming”, Luigi Montano, a researcher at the University of Rome and study lead author, said.