You Are What You Eat: Microplastics Are Identified in Feces of Male Young Adults Living in Beijing

Abstract

Background: Microplastics have been widely detected in environment, even in water systems and food, and become a severe global threat to sustainable development. However, few studies have investigated the presence of microplastics in humans. This study identified and quantified the microplastic content in human feces. Methods: In total, 26 male students aged 18-25 years were recruited in Beijing, China. Anthropometric measurements, including height and weight, were collected. A self-administered 7-day 24-h fluid intake record was used to document fluid intake, and food intake was recorded 3 days before the collection of feces. Newly excreted feces were collected by participants using a sterile fecal collector. Microplastics in the remaining fecal residues were measured using Fourier transform microinfrared spectroscopy after pretreatment. Eight types of microplastic were identified and analyzed. Findings: The fecal samples of 23 (95·5%) participants tested positive for microplastics. Among these 23 samples, the abundance of microplastic varied from 1 particle/g to 36 particles/g, and the mass of microplastics ranged from 0·01 to 14·6 mg. Qualitative analysis of the microplastic indicated the presence of one to eight types of microplastic in each sample, with the relative mass abundance ratio of polypropylene (PP) being the highest at 61·0%. PP was found in 95·8% of fecal samples. Compared with the participants in the high-abundance group, those in the low-abundance-group consumed more bottled water and beverages (1071 vs 840 mL, Z = -2·078, p = 0·038). Interpretation: Various types of microplastic were detected in human feces, with the highest proportion being PP. Participants with more microplastics in their feces consumed more bottled water and beverages. More studies should explore the possibility of detecting microplastics in the human body, possible sources of microplastics, and the effects of microplastics on human health. Funding: There is no funding. Declaration of Interest: The authors declare that they have no competing interests. Ethical Approval: The study protocol and instruments were reviewed and approved by the Institutional Review Committee of Peking University. The ethical approval project identification code is No. IR1052-19051. The study was conducted according to the guidelines of the Declaration of Helsinki. Prior to the study, all participants read and signed informed consent forms.