Based on recent studies it is hypothesized that microplastics and nanoplastics (MNPs) are present in human's ileum, colon, and rectum and that their presence may have a correlation with Inflammatory Bowel Disease (IBD).

This study is a cross-sectional, single-center, non-profit observational study. The main objectives are to define in vitro the presence of MNPs in the humans ileum, colon, and rectum and to evaluate if there is a correlation between this presence and IBD. In vitro metabolomics and proteomics analyses of the study sample and the assessment of participants' daily plastic exposure are considered exploratory objectives. For this purpose, a total of 102 patients undergoing a surgery where intestinal resection is included, will be enrolled.

Based on recent studies, it is hypothesized that MNPs are present in the human's ileum, colon, and rectum and that this presence may have a correlation with Inflammatory Bowel Disease (IBD).

This study is a cross-sectional, single-center, non-profit, observational study in which filling out, una-tantum, the daily plastic exposure 10-minute questionnaire is the only additional procedure. Adult patients who will be subjected, as established by normal clinical practice, to any type of bowel surgery that involves resection of colon, ileum and/or rectum, will be included (n=102). Participants will be divided in two groups, Group IBD (n=51) and Group Non IBD (n=102).

This study does not add additional clinical practices or controls to the participants and there are not follow up visits programmed. Furthermore, this study does not add additional risks to patients since the intestinal resection is done during surgery according to standard clinical practice.

The study population includes patients who will be subjected, as established by normal clinical practice, to any type of bowel surgery that involves resection of colon, ileum and/or rectum and the study object is to determine the presence, composition, and potential health implications of microplastics and nanoplastics in the human ileum, colon, and rectum. Focusing on whether the presence of these particles correlates with intestinal inflammatory processes.

For this purpose, the primary objective of this study is to determine the presence of microplastics and nanoplastics in the humans ileum, colon, and rectum. The secondary objective is to evaluate if there is correlation between the presence of the microplastics and nanoplastics in the humans bowel and Inflammatory Bowel Disease (IBD). Finally, the exploratory objectives are to analyze further characteristics of the study sample such as the metabolomics and proteomics characteristics and to assess participants' daily plastic exposure.

The study will have a total duration of 15 months and includes 9 months of enrollment and 6 months for laboratory analysis. All the collected samples will be analyzed in vitro by the following methods:

• MNPs presence determination and characterization
• Metabolomics
• Proteomics

Inclusion Criteria:

• Patients who will undergo any type of bowel surgery due to any type of clinical condition, as established by normal clinical practice, where colon, ileum and/or rectum resection is involved.
• Patients aged ≥ 18 years.
• Patients who have read, understood, accepted, and signed the informed consent to the study.
• Female patients within and outside of childbearing age (breastfeeding women can be included in the study)

Exclusion Criteria:

• Patients aged < 18 years.
• Pregnant women.
• Patients who have not accepted informed consent.

The study population includes patients who will be subjected, as established by normal clinical practice, to any type of bowel surgery that involves resection of colon, ileum and/or rectum. The participants will be male and female subjects, with age ≥ 18 years.