Breakthrough Findings from Perth's PERTH Trial

A groundbreaking clinical trial conducted by researchers at the University of Western Australia has demonstrated that simple changes in daily habits can dramatically lower levels of harmful plastic-associated chemicals in the human body. The Plastic Exposure Reduction Transforms Health, or PERTH Trial, revealed that avoiding plastic food packaging, using non-plastic kitchenware, and switching to low-plastic personal care products led to reductions of up to 60 percent in key chemicals within just seven days. This study, published in the prestigious journal Nature Medicine, marks a significant step forward in understanding how everyday plastic exposure impacts health and offers practical strategies for mitigation.

Led by Clinical Professor Michaela Lucas from UWA's Medical School, the trial involved a cohort of 211 healthy Perth adults and a randomized controlled pilot with 60 participants. All cohort members tested positive for at least six plastic-associated chemicals, or PACs, in their urine, underscoring the ubiquity of these substances in modern life. The rapid clearance observed in the intervention groups highlights the body's ability to eliminate these compounds quickly when exposure is curtailed.

Understanding Plastic-Associated Chemicals: Phthalates and Bisphenols

Phthalates, often abbreviated as phthalates (pronounced 'thal-ates'), are a group of chemicals used to make plastics flexible and durable. Di(2-ethylhexyl) phthalate (DEHP), mono-n-butyl phthalate (MnBP), and mono-benzyl phthalate (MBzP) are among the most common, found in soft plastics like cling wrap, food containers, and even some washing powders. Bisphenols, such as bisphenol A (BPA) and its substitute bisphenol S (BPS), harden plastics and line canned goods, migrating into food especially when heated.

These endocrine-disrupting chemicals mimic hormones, interfering with reproductive, metabolic, and developmental processes. In Australia, where plastic packaging dominates supermarket shelves, exposure is pervasive. Studies show phthalates and bisphenols in wastewater and diets contribute to widespread human contact, with links to infertility, obesity, type 2 diabetes, and cardiovascular disease. The PERTH Trial quantified this by measuring urinary metabolites—breakdown products excreted in urine—revealing higher levels in those consuming highly processed or canned foods.

The Design and Execution of the PERTH Trial

The PERTH Trial combined an observational cohort study with a rigorous seven-day randomized controlled trial (RCT). Researchers recruited 211 Perth adults aged 18-70, excluding pregnant individuals or those with severe allergies. Baseline urine, nasal swabs, and questionnaires assessed PAC exposure via tools like the Plastic-Associated Chemical Exposure Questionnaire (PACeQ) and 24-hour dietary recalls adjusted for plastic contact.

For the RCT, 60 participants were randomized into five groups: low-plastic food only; food plus plastic-free kitchenware (stainless steel pots, wooden boards); low-plastic personal care products (PCPs) alone; full intervention (all three); and control. UWA dietitians collaborated with over 100 local producers to supply 'paddock-to-plate' food minimizing plastic—from farming to delivery—while matching usual calorie intake and preferences. Adherence was high, with daily spot urine samples pooled and analyzed using liquid chromatography-mass spectrometry for precise metabolite detection.

Striking Results: Rapid Declines in Chemical Levels

The cohort confirmed universal exposure: every participant excreted multiple PACs, with BPA levels comparable to US cohorts but DEHP metabolites fivefold higher than American averages. Highly processed foods correlated with elevated phthalates, while canned items boosted BPA by 14 percent per serving.

In the RCT, interventions slashed urinary levels versus controls. The full-intervention group saw MnBP drop 44 percent, MBzP by 53.5 percent (95% CI: -72.7 to -20.6), and BPA by 59.7 percent (95% CI: -82.5 to -6.87). Low-plastic food alone reduced sum bisphenols by 58.5 percent; kitchenware changes targeted phthalates effectively. Even PCP swaps cut MnBP by 35 percent independently. Nasal swabs showed BPA clearance, affirming reduced inhalation from kitchen vapors.

Unexpectedly, higher body fat was linked to lower certain phthalates, possibly due to sequestration, while DEHP metabolites inversely correlated with inflammation markers like high-sensitivity C-reactive protein (hsCRP) and lipoprotein(a) (Lp(a)). These findings, adjusted for age, sex, and fat mass index, underscore modifiable risks.

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UWA Researchers Driving Change in Environmental Health

At the helm is Clinical Professor Michaela Lucas, an immunologist with expertise in chronic disease and plastics' health effects. 'Strictly adhering to a diet where food hasn't touched plastic can reduce these chemicals in as little as a week,' she noted. Co-first authors Dr. Amelia Harray, a dietitian specializing in sustainable eating, and Dr. Andrew Lucas, focused on analytical chemistry, highlight interdisciplinary collaboration.

The team, including experts from UWA's School of Biomedical Sciences and Centre for Applied Statistics, partnered with Queensland Alliance for Environmental Health Sciences for chemical analysis. Funded by the Minderoo Foundation, the trial exemplifies UWA's leadership in translational research addressing Australia's plastic pollution crisis.

Health Implications for Australians

Australia produces over 2.5 million tonnes of plastic waste yearly, with packaging comprising 40 percent. Phthalates and bisphenols leach into food via heat, acidity, or fat content, entering the bloodstream rapidly. Linked risks include reduced sperm quality—vital amid Australia's fertility rate of 1.6 births per woman—and rising cardiometabolic diseases costing $23 billion annually.

The PERTH Trial's cardiometabolic focus revealed inverse links between DEHP exposure and inflammation, suggesting complex interactions. Yet, rapid clearance implies prevention could avert long-term harm. For vulnerable groups like pregnant women or children, where early exposure heightens asthma or obesity risks, these insights are crucial. Professor Lucas warns no 'safe' level is established, urging policy shifts.

For deeper reading on the study's methodology and data, explore the full publication in Nature Medicine.

Practical Steps to Minimize Plastic Exposure

Embracing a low-plastic lifestyle is feasible, as proven by trial participants maintaining energy intake. Key actions:

• Choose fresh, unpackaged produce from farmers' markets or bulk bins.
• Avoid canned foods; opt for glass jars or tetra paks.
• Use stainless steel, glass, or wood for storage, cutting, and cooking—no microwaving plastics.
• Screen PCPs via apps or labels for 'phthalate-free' and 'BPA-free'.
• Prioritize whole foods over ultra-processed items.

Participant Simmone Sache shared challenges like higher costs but benefits in well-being. UWA's collaboration with 100+ producers shows scalability. Dr. Harray emphasized transforming supply chains: 'From paddock to plate without plastic.'

Australia's Plastic Landscape and Policy Gaps

Australia lags globally in plastic regulation; only Tasmania bans microbeads, and recycling rates hover at 13 percent for packaging. The National Plastics Plan aims for 100 percent reuse by 2025, but enforcement is weak. Wastewater studies detect phthalates nationwide, with Perth levels elevated versus US norms.

The trial's findings bolster calls for bans on phthalates in food contact materials, echoing EU restrictions. ABC coverage notes public health urgency, with experts advocating labeling reforms. Coverage in ABC News amplifies the message.

Photo by Daryl Edwin on Unsplash

Future Directions: Fertility and Beyond

UWA's next PERTH phase targets fertility, recruiting those with reproductive challenges. Building on inverse DEHP-cardiometabolic links, longitudinal studies will probe causality. Professor Lucas: 'We need to define safe levels and health endpoints.'

Minderoo Foundation's John Hartman stresses pervasive exposure: 'Plastic chemicals in every Perth adult.' Global implications extend to microplastics, with UWA tools like dietary plastic scorers aiding research.

Challenges, Limitations, and Broader Perspectives

While adherence was 100 percent, real-world scalability faces cost and access barriers. The seven-day pilot limits long-term insights; stool microplastics await analysis. Yet, the trial's rigor—creatinine-adjusted LC-MS/MS, multilevel modeling—sets a gold standard.

Stakeholders, from producers to policymakers, praise UWA's innovation. Dr. Andrew Lucas notes BPS as a concerning BPA substitute. Overcoming these hurdles could redefine public health in plastic-saturated Australia.