Eight PFAS compounds detected at low concentrations in Melbourne rain

Researchers from RMIT University and EPA Victoria have identified eight distinct PFAS compounds in rainwater samples collected in Melbourne between 2024 and 2025. PFAS are a diverse group of man-made chemicals used in various products including firefighting foams, food packaging, textiles, cosmetics, and nonstick cookware. While the discovery may provide reassurance to those relying on rainwater tanks, the study also sheds light on how these chemicals can reach waterways from seemingly unexpected sources.

PFAS can enter the atmosphere attached to dust particles or moisture, eventually falling back to Earth through rainfall. Based on rainfall data and concentrations measured in the study, researchers estimate that rain could deliver approximately 10.6 kilograms (23.4 pounds) of PFAS to Port Phillip Bay annually. To put this into perspective, this equates to around 5.5 grams per square kilometer across the bay's 1,930 square kilometer surface area.

This estimate suggests that rainfall could play a significant role in transporting PFAS into waterways, alongside more conventional sources like wastewater, urban runoff, and landfills. Professor Oliver Jones from RMIT's School of Science, who led the study, emphasized that the findings fill a gap in understanding how PFAS can appear in areas with no obvious nearby sources.

He noted that while detecting PFAS in rain isn't surprising given their widespread presence, the crucial question is whether the concentration poses a health risk. He clarified that the more pertinent question is the dose and exposure, rather than simply whether a chemical is toxic. The study's lead author, doctoral student Nav Singh, highlighted that the research contributes valuable knowledge to the growing concern over PFAS in the environment.

This finding comes as part of a broader effort to better understand how PFAS move through the environment and to improve monitoring practices across Australia. Jones noted that while PFAS are often referred to as "forever chemicals," a more accurate description is that they are highly persistent chemicals that can linger in the environment for extended periods.

This study, published in the journal Environmental Toxicology and Chemistry, highlights the importance of robust, peer-reviewed evidence in informing effective regulation, risk assessment, and management of these persistent substances.