After just 7 days of less plastic, the levels of some substances associated with diabetes and infertility can drop by half

One week of targeted changes in diet and personal care product choices is enough to reduce the level of phthalates and bisphenols in urine by about 50%, according to a study published in late April 2026 in the journal Nature Medicine.

The effects of small lifestyle changes appear quickly and are measurable without drugs or complicated interventions, just by choosing other food sources and plastic-free cosmetics, researchers from the University of Western Australia have found.

The data, obtained from tests done on 60 adults divided into five groups, were confirmed by a parallel group, which included 211 participants. Each person tested had at least six substances associated with plastic in their urine. The team's conclusion is that daily exposure, although massive, can be reduced through personal choices as long as they are maintained over the long term.

The study, called the PERTH Trial (Plastic Exposure Reduction Transforms Health), took place over seven days and looked at two main categories of substances: phthalates, used to make plastic more flexible, and bisphenols, the best known of which is BPA, present in epoxy resins used inside metal cans and in polycarbonates.

Both types are classified as endocrine disruptors, meaning they mimic or block the action of hormones, and epidemiological evidence accumulated in recent years has linked them to type 2 diabetes, obesity, cardiovascular disease, thyroid dysfunction, and fertility problems.

How do these substances get into the body?

Australian researchers worked with more than 100 local farmers and producers, training them to change the way they package and handle food so that the journey from farm to table involves as little contact with plastic as possible. The food parcels were delivered in cardboard boxes insulated with sheep's wool, without plastic bags or foils, and canned goods were completely removed from the menu.

Dr. Amelia Harray, lead author of the study, explained the scale of the study: “Our nutritionists worked with over 100 farmers and food producers to educate them and transform their handling and packaging processes to reduce their exposure to plastic from farm to plate.”

Following the intervention, the team identified three main sources of plastic chemicals that anyone can avoid. The first is the packaging: even fresh fruits and vegetables wrapped in foil or in plastic pots transfer some of these substances. The second is cans and drinks in a metal dose, because the inner lining of the can usually contains BPA or its substitutes, and they pass into the acidic or warm food. The third category is represented by ultra-processed foods, which are exposed to plastic at every industrial stage, from production to transport and packaging. An observational analysis from the same study shows that for every canned food eaten daily, urinary BPA levels increase by 14.3%.

“By changing the participant's lifestyle to include eating food with less plastic, cooking with non-plastic kitchen utensils and using personal care products in non-plastic containers, phthalates decreased by more than 44% and bisphenols (including BPA and BPS) by more than 50%,” pointed out Dr. Andrew Lucas, one of the authors of the study.

Cosmetics, shampoo and toothpaste

Another stage of the analysis separated the effect of personal care products. One group of participants kept their usual diet, but replaced the toothpaste, shampoo, conditioner, deodorant, tampons and other products used daily with alternatives selected by the researchers to contain as little plastic and synthetic fragrances as possible. After seven days, mono-n-butyl phthalate, a metabolite used as an indicator of exposure to low molecular weight phthalates, decreased by about 35% compared to the control group, with no change in diet.

“We investigated two major types of plastic chemicals, bisphenols and phthalates, both of which can interfere with our body's endocrine or hormonal functions and are linked to infertility and cardiometabolic diseases,” explained Prof. Michaela Lucas, project coordinator.

However, the exact source of the reduction remains difficult to isolate. Synthetic fragrances are a known source of phthalates in cosmetics, especially in products used daily. At the same time, plastic containers can also contribute to exposure. That's why the authors recommend fragrance-free products first, and where possible, options with less plastic, such as solid shampoos or creams packaged in metal containers.

How exposed Europeans are

Global data show that these substances are universal. In the Australian cohort, each participant had at least six plastic-related compounds in their urine on a typical day. At the European Union level, the HBM4EU biomonitoring program, carried out between 2014 and 2021 in 23 countries, tested 10,795 people in three age groups: 3,576 children between 6 and 12 years, 3,117 adolescents between 12 and 18 years and 4,102 young adults between 20 and 39 years. The conclusion was that exposure to phthalates and bisphenols is detectable in all countries, and people from households with lower educational levels had significantly higher urinary values ​​for bisphenols, phthalates and parabens.

In April 2023, the European Food Safety Authority (EFSA) published a reassessment of the health risks associated with BPA in food and reduced the Tolerable Daily Intake (TDI) from 4 micrograms per kilogram of body weight per day, a temporary value set in 2015, to 0.2 nanograms per kilogram per day. The new limit is 20,000 times lower and means that the average exposure of the European population now exceeds the new safety threshold. In December 2024, the European Commission adopted a regulation banning the use of BPA in food contact materials, which came into force in January 2025, with some limited exceptions.

What effects do phthalates and bisphenols have?

The two families of compounds act on hormone receptors and can influence lipid metabolism, insulin sensitivity and the immune system. In the PERTH cohort, the authors observed negative associations between di-2-ethylhexyl phthalate (DEHP) metabolites and cardiometabolic biomarkers, such that individuals with higher urinary levels of these compounds had less favorable lipid and inflammatory profiles.

Previous studies published in international journals have linked chronic exposure to phthalates with a higher risk of asthma in children, neurocognitive developmental delays and male fertility problems.

In the case of BPA, EFSA's decision to drastically reduce the dose considered tolerable was mainly based on data related to the immune system. Experts have observed, in animal studies, an increase in T helper 17 cells, involved in the inflammatory response. EFSA considered this change relevant for human health.

The three simple changes that reduce your exposure to plastic

The authors of the study point out that there are no miracle recipes. Toxicologist Matthew Campen of the University of New Mexico College of Pharmacy in the US said sustained behavioral changes and dietary improvements would lead to long-term reductions in exposure and thus health risks. A single week without plastic will not have clinical effects, but it shows that the body reacts quickly when the flow of substances is stopped.

The results of the study revealed some easy-to-implement changes. The first involves the replacement of soft drinks by the dose with bottled versions, even for a part of the daily consumption. For those who are in the habit of drinking soda every day, the reduction can be significant, considering that every food or drink in metal packaging increases urinary BPA levels by 14.3%.

The second concerns the choice of fragrance-free hygiene products, especially lotions, creams, deodorants.

The third change concerns food. Plastic containers for hot food, plastic foil, black cooking utensils made of recycled materials should be gradually replaced by glass, ceramic, stainless steel or wooden variants. Plastic packaging is less problematic in contact with cold food than that exposed to heat or grease, but the general reduction of contact with heat-processed plastic remains a useful rule of thumb.

However, the PERTH trial has several limitations mentioned by the authors, including the short follow-up period. Seven days is enough to measure urinary levels, but not to see if the changes translate into clear clinical benefits, such as lower blood pressure, a better glycemic profile, or optimized levels of inflammatory markers. Also, the sample size is too small and limits statistical relevance for secondary analyses. The Perth team announced that they are planning a four-week follow-up and a larger number of participants with cardiometabolic risk factors to also see concrete effects on biomarkers.