Project PHOENIX: Molecular Signatures of Burn Pit Exposure

Inclusion Criteria: * Age 18 years or older at the time of consent * Former or current U.S. Service Member, including Active Duty, Reserve, National Guard, or Veteran status * For exposed cohort: prior deployment to a location with known burn pit operations, based on participant report and available confirmation when feasible * For control cohort: no known deployment to burn pit locations * Able and willing to provide informed consent and HIPAA authorization * Willing to complete study questionnaires and donate venous blood sample * Able to complete study procedures in English or with approved translation support * Available for one baseline visit and optional future re-contact, if applicable Exclusion Criteria: * Active serious illness or infection that, in the investigator's judgment, would compromise participation or specimen integrity * Receipt of systemic chemotherapy, immunotherapy, or radiation therapy within the past 6 months * High-dose systemic immunosuppression, defined as more than 20 mg prednisone equivalent daily for more than 14 days within the past 3 months * Pregnant or currently breast-feeding * Hemoglobin less than 10 g/dL, known bleeding disorder, or platelet count less than 100 × 10\^9/L, if known * Severe psychiatric illness or other condition that impairs ability to provide informed consent * Prisoner or institutionalized individual * Prior participation in this or a related Project PHOENIX protocol * Any other condition that, in the investigator's j…