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 exposure at both behavioral and biological levels. Integrating Pender's Health Promotion Model with objective biomarker assessment may contribute to the development of feasible and evidence-based strategies for reducing EDC exposure among women of reproductive age.