Scientists in Australia are launching one of the most comprehensive trials to date to test whether ditching plastics in food, personal care, and household products can lower internal chemical loads and improve markers of cardiometabolic health.
Protocol: Randomised controlled trial of a low plastic diet and lifestyle intervention for adults with cardiometabolic risk factors: the Plastic Exposure Reduction Transforms Health (PERTH) trial – a protocol. Image Credit: Oksana Mizina / Shutterstock
In a recent public health protocol published in BMJ Open, researchers describe the PERTH (Plastic Exposure Reduction Transforms Health) trial, a new randomized controlled study protocol designed to investigate whether a comprehensive, 4-week "low-plastic" diet and lifestyle intervention can reduce exposure to plastic-derived chemicals.
These chemicals, such as bisphenols and phthalates, are ubiquitous endocrine disruptors with documented links to obesity and cardiometabolic disease. The PERTH trial examines whether a cohort of 60 adults with cardiometabolic risk factors, provided with all-plastic-free food, cookware, and personal care products, can demonstrate measurable reductions in plastic-associated chemical excretion and exploratory changes in cardiometabolic biomarkers.
Background
From the top of Mt. Everest to the bottom of the Mariana Trench, plastics from food packaging, kitchen utensils, cosmetics, and cleaning supplies can be found everywhere and comprise an inescapable part of modern life. Alarmingly, in addition to their ecological and environmental impacts, a growing body of scientific literature reports extensive physiological concerns associated with them.
Two classes of chemicals commonly used in plastics: 1. bisphenols (like Bisphenol A [BPA]) and 2. phthalates (like diethyl phthalate [DEP]) are known endocrine disruptors. Observational research has linked higher exposure to these “plastic-associated chemicals (PACs)” with various adverse physiological outcomes, including obesity, insulin resistance, and systemic inflammation.
Clinical evidence suggests these outcomes substantially increase individuals’ risk and severity of cardiometabolic disease. Unfortunately, whether actively and drastically reducing PAC exposure can reverse previous harm remains to be investigated through controlled intervention studies.
About the proposed study (PERTH)
The present public health protocol details the proposed methodology of the Plastic Exposure Reduction Transforms Health (PERTH) trial, a randomized controlled trial (RCT) designed to test the efficacy of a low-plastic lifestyle intervention on measurable health outcomes in adults with cardiometabolic risk factors.
The study will involve 60 community-dwelling adults (aged 18–60 years) in Perth, Australia, who have established cardiometabolic risk factors. Study inclusion criteria include: 1. A body mass index (BMI) ≥30 kg/m², and 2. A high waist circumference (≥102 cm in men, ≥88 cm in women). The study will randomly assign participants into a case (“intervention”; n = 30) or control (n = 30) group.
The intervention period will last four weeks, during which time the intervention cohort participants will receive a comprehensive, all-inclusive low-plastic lifestyle package. This includes: 1. Delivering all food and beverages in plastic-free packaging, 2. Replacement plastic-free kitchenware (e.g., stainless steel pots, glass containers), 3. Personal care products (such as shampoo and soap), and 4. Cleaning supplies.
Interventional group participants will receive detailed instructions on how to minimize plastic exposure in their daily lives. In contrast, the control group will be asked to maintain their routine lifestyle and dietary patterns.
Study outcomes will be measured by evaluating the change in a composite z-score of urinary bisphenol concentrations (BPA and BPS) between participants in the intervention and control groups. Secondary and tertiary outcomes will include changes in urinary phthalate metabolites and a range of key health markers, including cardiometabolic biomarkers, blood pressure, and body composition. Participants will also collect their own stool and nasal lavage samples to support exploratory analyses.
Participants’ sociodemographic information will be recorded at baseline, and all biomedical measurements will be taken at baseline, midpoint (week 2), and at the end of the 4-week intervention.
Study design and significance
By providing all food and products to the intervention group, the PERTH trial will be the most comprehensive and rigorously controlled trial ever conducted on the topic. Impressively, pilot trials have already revealed that BPA was detectable in over 91% of urine samples derived from healthy (no cardiometabolic disease) adults, confirming that PAC exposure is widespread in Australia.
These pilots further demonstrated that a 7-day low-plastic intervention could significantly reduce urinary PAC levels, providing a strong basis for this larger, longer trial. Notably, while laboratory staff will be blinded to participant allocation, both participants and investigators cannot be blinded due to the nature of the intervention.
Finally, the PERTH study leverages the Plastic-Associated Chemical-exposure Questionnaire (PACeQ) to meticulously track and assess all potential routes of plastic exposure (ingestion, inhalation, and absorption), ensuring robust and trustworthy results. The protocol also highlights the ethical rationale for the holistic intervention approach, as it avoids artificial PAC exposure in controls due to safety concerns.
Conclusions
The PERTH trial is a critically important study that will provide the first protocolised attempt to test the causal effects of whether a comprehensive reduction in exposure to everyday plastic chemicals can lead to exploratory improvements in cardiometabolic health markers.
Study outcomes have the potential to significantly impact public health guidelines, inform regulatory policy on the use of chemicals in consumer products, and empower individuals with practical, evidence-based strategies to reduce their body's plastic burden. While the study’s Australian focus prevents its global generalizability, it comprises the first significant step from observational links to real-world interventions.
Journal reference:
- Lucas, A., Harray, A., Duong, L., Herrmann, S., Vlaskovsky, P., Trevenen, M., Chan, D., Papendorf, H., Smith, T., Flint, L., Liu, A., Gaudieri, S., Wang, X., Mueller, J., Thomas, K. V., Murray, K., Symeonides, C., & Lucas, M. (2025). Randomised controlled trial of a low plastic diet and lifestyle intervention for adults with cardiometabolic risk factors: the Plastic Exposure Reduction Transforms Health (PERTH) trial—a protocol. BMJ Open, 15(8), e099330. DOI – 10.1136/bmjopen-2025-099330. https://bmjopen.bmj.com/content/15/8/e099330