A frying pan in the kitchen. A rainproof jacket hanging near the door. Fast-food wrappers tossed into the bin. For millions of people, these ordinary objects may now be part of a much bigger public health problem quietly building inside the human body.

A massive new American study has found that man-made “forever chemicals”, known as PFAS, were detected in 98.8% of more than 10,500 blood samples tested, raising fresh concerns that exposure to these substances has become nearly impossible to avoid in modern life.

The findings, published in the peer-reviewed Journal of Occupational and Environmental Hygiene, offer one of the clearest snapshots yet of how deeply these chemicals may have entered human bodies. Researchers examined 10,566 serum and plasma samples and discovered that most people were not carrying just one PFAS chemical, but several at the same time.

PFAS stands for per- and polyfluoroalkyl substances, a family of nearly 10,000 industrial chemicals widely used for decades because they resist heat, oil, grease and water. Scientists call them “forever chemicals” because they break down extremely slowly and can remain in the environment — and the human body — for years.

They are found in non-stick cookware, stain-resistant carpets, waterproof clothing, food packaging, electronics, firefighting foam and even some medical equipment. Tiny amounts can enter food and drinking water and slowly accumulate in the body over time.

Inside laboratories at NMS Labs in the United States, toxicologists processed thousands of blood samples under bright fluorescent lights, searching for patterns hidden in microscopic chemical traces. What they found was unsettlingly consistent.

Overall, 98.8% of the samples contained at least one PFAS chemical. Only 19 samples showed a single PFAS at the lowest reporting threshold. Most people carried mixtures of five or more.

One chemical, perfluorohexane sulfonic acid, also referred to in the study alongside linear PFOA compounds, appeared in 97.9% of samples tested. Previous scientific research has linked some PFAS chemicals to serious health concerns including cancer, infertility, weakened immunity, liver damage, thyroid disorders and high cholesterol.

“These findings reinforce that PFAS exposure rarely occurs as isolated compounds,” said Dr Laura Labay, Principal Toxicologist at NMS Labs and lead author of the study.

“Instead, individuals typically carry body burdens comprising five or more PFAS with differing bioaccumulation properties and half-lives.”

The most common chemical combination identified in the study included five PFAS compounds frequently associated with consumer products such as non-stick pans, stain-resistant fabrics and firefighting foam. That specific mixture appeared in more than one-fourth of all samples tested.

Dr Labay said the findings could help scientists better understand the health risks of combined chemical exposure rather than examining one chemical at a time.

“This large dataset provides a real-world snapshot of how multiple PFAS commonly occur together in people,” she said.

“By identifying these shared exposure patterns, the study offers a greater understanding of what widespread, combined PFAS exposure may mean for human health.”

The warning signs around PFAS have been growing worldwide. Earlier studies by the United States Environmental Protection Agency and the World Health Organization have raised concerns about contaminated drinking water, industrial waste and long-term health risks. Several countries are now debating stricter limits on PFAS use as evidence continues to grow.

Scientists say one troubling issue is that these chemicals do not stay in one place. They travel through rivers, soil, food chains and household dust. Once inside the body, some PFAS may remain for years before levels slowly decline.

The researchers also acknowledged limitations in the study, noting that not all possible PFAS chemicals were tested. That means the real extent of exposure may actually be higher.

For ordinary people, the report delivers a difficult message. The chemicals linked to modern convenience — easier cooking, waterproof clothing, grease-proof packaging — may also be creating an invisible biological burden carried silently in bloodstreams across generations.