This study looks at whether certain environmental chemicals, called organic pollutants, build up in the body fat and stomach tissues of people with obesity who are having weight-loss (bariatric) surgery. These pollutants can come from things like plastics, pesticides, or industrial waste, and may affect health in different ways.

The investigators will measure the amount of these pollutants in tissue samples taken during surgery and see if the levels are different in people with mild, moderate, or severe obesity. By understanding these patterns, the investigators hope to learn more about how environmental factors may influence obesity and related health problems. The findings could help guide future prevention and treatment strategies for patients.

Obesity is a complex health condition influenced by both lifestyle and environmental factors. Among these factors, persistent organic pollutants (POPs) - such as certain plastic-related chemicals, pesticides, and industrial byproducts - have raised growing concern due to their ability to accumulate in human tissues over time and potentially interfere with metabolism.

This study focuses on patients with obesity who are undergoing bariatric surgery. During surgery, the investigators will collect small samples of adipose (fat) tissue and gastric tissue under sterile conditions. These samples will be analyzed for the presence and concentration of specific organic pollutants using validated laboratory methods. The investigators will compare pollutant accumulation patterns across patients with varying levels of obesity severity, aiming to identify possible associations between pollutant burden and obesity-related clinical characteristics.

The results are expected to provide new insights into the environmental contributions to obesity, beyond diet and physical activity. By clarifying how pollutant accumulation in different tissues relates to obesity severity, the findings could help inform prevention strategies, refine clinical management, and highlight the need for targeted public health policies addressing environmental exposures.

Inclusion Criteria:

• Adults ≥18 years.
• BMI ≥30 kg/m² at screening (measured within 30 days before surgery).
• Scheduled for primary bariatric surgery (e.g., sleeve gastrectomy or Roux-en-Y gastric bypass) for clinical indications.
• Able to provide informed consent.
• Willing to allow intraoperative collection of subcutaneous/visceral adipose tissue and gastric tissue for pollutant analysis.
• Availability of basic preoperative clinical data (demographics, comorbidities, relevant labs).

Exclusion Criteria:

• Prior bariatric or major upper gastrointestinal surgery that alters stomach/anatomy relevant to sampling.
• Pregnant or breastfeeding at screening or on day of surgery.
• Active malignancy (excluding non-melanoma skin cancers) or ongoing systemic immunosuppressive therapy (e.g., chronic corticosteroids, biologics) within 3 months.
• Severe organ dysfunction: decompensated cirrhosis (Child-Pugh C) or eGFR <30 mL/min/1.73m².
• Acute infection or decompensated chronic illness that would preclude elective surgery per treating team.
• Documented high-level occupational or accidental chemical exposure within 6 months (e.g., pesticide poisoning) likely to bias tissue pollutant measurements.
• Participation in another interventional study expected to affect weight or metabolism within 3 months.
• Inadequate tissue obtainable at surgery for analysis (determined intraoperatively by the investigators).

The study population will consist of adult patients with obesity (BMI ≥30 kg/m²) scheduled to undergo primary bariatric surgery, including sleeve gastrectomy or Roux-en-Y gastric bypass, at participating surgical centers. Participants will represent a range of obesity severities (Class I-III) and may have obesity-related comorbidities such as type 2 diabetes, hypertension, dyslipidemia, or obstructive sleep apnea. All participants must be able to provide informed consent and agree to intraoperative collection of adipose and gastric tissue samples for organic pollutant analysis.

individual participant data (IPD) will not be shared due to concerns regarding patient privacy, the sensitive nature of surgical and tissue analysis data, and applicable institutional and regulatory restrictions. Summary-level results will be made available in publications and presentations.