Low-plastic diet and urinary levels of plastic-associated phthalates and bisphenols: the randomized controlled PERTH Trial

The everyday use of plastic products exposes us to plastic-associated chemicals (PACs), which have been associated with risks to human health. We present the results of the Plastic Exposure Reduction Transforms Health Trial, with an observational cohort of 211 Australian participants and a 7-day pilot randomized controlled trial in 60 participants. Intervention groups received combinations of plastic-free kitchenware, low-plastic personal-care products and food sourced from more than 100 producers that minimized all plastic touchpoints from paddock to plate, while the control group received no intervention. The primary trial outcome was a reduction in urinary plastics-associated chemicals levels. In the cohort study, highly processed, plastic-packaged and canned foods were important modifiable factors for urinary PAC metabolite levels. Additionally, we observed negative associations between cardiometabolic biomarkers and higher urinary di(2-ethylhexyl) phthalate metabolites. Our randomized controlled dietary intervention maintained participants' daily energy intake while decreasing plastic exposure (P < 0.001) and urinary levels of mono-n-butyl phthalate, monobenzyl phthalate and bisphenol A by 37.5% (95% confidence interval (CI): -55.6, -12.0; P = 0.007), 53.5% (95% CI: -72.7, -20.6; P = 0.005) and 59.7% (95% CI: -82.5, -6.87; P = 0.033), respectively. Intervention groups provided with foods that had minimal to no contact with plastic had the broadest effect on PAC excretion, and replacing low-plastic personal-care products alone led to an independent decrease in urinary mono-n-butyl phthalate, compared to no intervention. Despite constant plastic exposures, limiting food plastics touchpoints decreases select PACs in 7 days. Australian and New Zealand Clinical Trials Registry: ACTRN12622001252707 .