Exposure to microplastics and human reproductive outcomes: A systematic review

Background: Microplastics, produced through degradation of environmental plastic pollution, have been detected in human tissues including placenta and fetal meconium. Cell culture and animal studies have demonstrated potential reproductive toxicity of these particles; however, their association with adverse fertility or pregnancy outcomes in humans is not known.

Objectives: To synthesise evidence for the presence of microplastics in human reproductive tissue and their associations with environmental exposures and reproductive outcomes.

Search strategy: MEDLINE, Embase, Emcare, CINAHL, ClinicalTrials.gov and ICTRP were searched from inception to 03/02/2023.

Selection criteria: Studies of human participants, assessing presence of microplastics in reproductive tissues, environmental exposures to microplastics, and fertility- or pregnancy-related outcomes.

Data collection and analysis: Two independent reviewers selected studies and extracted data on study characteristics, microplastics detected, environmental exposures and reproductive outcomes. Narrative synthesis was performed due to methodological heterogeneity.

Main results: Of 1094 citations, seven studies were included, covering 96 participants. Microplastics composed of 16 different polymer types were detected in both placental and meconium samples. Two studies reported associations between lifestyle factors (daily water intake, use of scrub cleanser or toothpaste, bottled water and takeaway food) and placental microplastics. One study reported associations between meconium microplastics and reduced microbiota diversity. One reported placental microplastic levels correlated with reduced birthweights and 1-minute Apgar scores.

Conclusions: There is a need for high-quality observational studies to assess the effects of microplastics on human reproductive health.