Organic Pollutant Build-Up in Body Fat and Stomach Tissue Linked to Obesity Levels

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.

• exposure to organic pollutant (Other): Small samples of subcutaneous and visceral adipose tissue will be analyzed for the presence and concentration of specific organic pollutants using validated analytical chemistry methods, such as gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry (LC-MS).

Primary outcomes

• Obesity Severity [At baseline (within 1 month before bariatric surgery).]: The investigators will assess obesity severity based on body mass index (BMI), calculated as body weight in kilograms divided by height in meters squared (kg/m²). BMI will be obtained using standardized measurements of height and weight during the preoperative evaluation. Obesity severity will be categorized according to World Health Organization (WHO) criteria (Class I: 30.0-34.9 kg/m², Class II: 35.0-39.9 kg/m², Class III: ≥ 40.0 kg/m²).

Sex: All, ages: 18 Years to any

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).