In the UK, tampons are being used to monitor rivers for signs of "grey water"—the bacteria-laden stuff that comes out of our shower drains and washing machines.
Grey water is ending up in our rivers as a result of bad plumbing, and seeking out its source is a typically time-consuming, expensive process. These clever tampons offer a cheaper option that's proven to be effective, all thanks to optical brighteners.
You see, tampons are made with untreated cotton that absorbs optical brighteners—chemicals used in detergents and shampoos. The chemicals glow under UV light, and when the untreated cotton in tampons absorbs these brighteners, it's a telltale sign that there's grey water contamination in the river.
A team from the University of Sheffield tied tampons to bamboo poles, then placed them in 16 water sewers to test for bacteria and contaminants. As expected, they confirmed a waste-water problem is happening in Sheffield, England, but on the plus side, they've found a cheap and simple way to monitor rivers.
This article originally appeared on Cosmopolitan.co.uk. Minor edits have been made by the Cosmo.ph editors.