Microplastics in human ovarian follicular fluid: a pilot Raman spectroscopy study

Microplastics (MPs) have recently been identified in multiple human biological matrices, including placenta, blood, breast milk, semen, and testicular tissue, raising concerns regarding their potential endocrine, inflammatory, and reproductive effects. Despite this rapidly expanding field, the ovarian follicular microenvironment remains largely understudied, and data on the direct presence of MPs in human follicular fluid (FF) are limited.

This pilot study aimed to qualitatively assess the presence and polymer composition of MPs in human FF obtained during in vitro fertilization (IVF) using a contamination-controlled workflow and confocal micro-Raman spectroscopy.

FF samples from 27 women undergoing IVF were processed under strict contamination-control conditions. Organic material was digested using 10% potassium hydroxide (KOH), followed by vacuum filtration through 1.6 µm glass-fiber filters. Filters were screened by optical microscopy, and suspected particles were analyzed using 532 nm confocal micro-Raman spectroscopy and matched against validated polymer spectral libraries. Procedural blanks were included in each analytical batch.

MPs were detected in 22 of 27 FF samples (81.5%). Positive samples contained between one and three particles. Identified polymers included polypropylene (PP; most frequent), polyethylene (PE), polyamide (PA), polystyrene (PS), and polyethylene terephthalate (PET). No MPs were detected in procedural blanks.

MPs were detectable in the majority of FF samples under contamination-controlled conditions. While the clinical implications remain unclear, these findings support the presence of MPs within the ovarian microenvironment and highlight the need for larger, standardized, and mechanistic studies.