You probably open your mailbox expecting to find letters. But one group of researchers in Canada hoped to receive packages of toenail clippings instead!
From 2009 to 2015, scientists with the Atlantic Partnership for Tomorrow’s Health (Atlantic PATH) asked people to mail in their toenail trimmings. Atlantic PATH is part of the largest long-term disease research project in Canadian history. The project studied toenail clippings to understand how harmful substances contribute to the development of diseases like cancer—when cells in the body grow out of control.
Why toenails? It’s because any toxins that enter a person’s body from the environment get incorporated into their nails as they grow. Trimmed portions of toenails have been growing for six to nine months. These clippings act like tiny time capsules, recording the contaminants a person has been exposed to.
The scientists received toenail samples from 30,418 individuals—setting a Guinness World Record for the largest-ever collection of clippings. “The toenails were as varied as the people who provided them,” says Jason Hicks, executive director of Atlantic PATH. “Some came with toenail polish and others with fungus.” Each sample was counted, recorded, and then crushed into a powder for analysis.
So far, the study’s findings have contributed to 80 research papers, including one that revealed information on how the body stores arsenic (As). This element, found naturally in some water sources, is linked to several types of cancer (see Name That Element!, Science World, March 17, 2025). Who knew it was possible to learn so much from toenail clippings?