Reducing Endocrine-Disrupting Chemical Exposure in Reproductive-Age Women: A Pender Model-Based RCT

Abstract Background: Endocrine-disrupting chemicals (EDCs) are widely encountered in daily life and may adversely affect reproductive health. Although awareness of EDC-related risks is increasing, interventions targeting modifiable exposure-related behaviors remain limited. Theory-based behavioral interventions that address self-efficacy, perceived barriers, action planning, and maintenance of health-promoting behaviors may provide an effective approach to reducing EDC exposure. Objective: This study aims to evaluate the effectiveness of a behavioral change intervention based on Pender's Health Promotion Model in reducing EDC exposure among women of reproductive age using both behavioral outcomes and urinary biomarkers. Methods: This study is designed as a biomarker-supported, two-arm, parallel-group, open-label randomized controlled trial. A total of 108 women aged 18-49 years will be randomly allocated in a 1:1 ratio to an intervention or control group. The intervention group will participate in a 12-week structured behavioral change program based on Pender's Health Promotion Model. The program will include education, goal setting, action planning, self-monitoring, problem solving, social support, behavioral rehearsal, environmental restructuring, and digital reinforcement messages delivered via WhatsApp. EDC-related exposure behaviors, exposure perception, and attitudes will be assessed using structured measurement tools. Urinary bisphenol A (BPA) and selected phthalate metabolites will be measured before and after the intervention using liquid chromatography-tandem mass spectrometry. The primary outcome will be the between-group difference in post-intervention urinary BPA levels adjusted for baseline BPA. Secondary outcomes will include urinary phthalate metabolites, exposure-related behaviors, exposure perception, and attitudes toward EDCs. Conclusion: This study will provide evidence on whether a theory-based behavioral change intervention can reduce EDC e