Just the Right Absorbency

More than a million homes in the United Kingdom discharge sewage directly into rivers and streams rather than to municipal treatment plants, and identifying those homes can be very difficult. The rogue effluent is obviously a bad (and smelly) scene for the environment and public health. A team of engineers from Sheffield University announced Friday that they have a solution: tampons.

Let me say that again. Tampons are going to help solve the U.K.’s untreated sewage problem. The scientists’ work will teach you something you likely didn’t know about water pollution and about tampons—we aim to inform here at Earthwire.

Untreated sewage pollutes waterways and contributes to algal blooms that choke marine life. The current approach to determining where a household’s sewage goes is to pour dye down the pipes, one home at a time, then send out a team of government employees to find where the colors appear. The process is slow, expensive, and labor-intensive.

Many household products, like laundry detergent and toilet paper, contain optical brighteners, and the presence of those chemicals indicates that untreated sewage is flowing into surface waters. Cotton has always seemed like a potential solution because it absorbs those optical brighteners. Environmental engineers could dip cotton into a stream, shine an ultraviolet light on it to detect untreated sewage, and then trace the water’s flow upstream to the home or homes it came from. It’s almost a great strategy, but there’s a problem: Most of the world’s cotton products already have brighteners in them. That’s why T-shirts glow so brilliantly at raves (or so I’m told).

Enter the tampon. The cheap and readily available feminine hygiene product is typically made of untreated cotton and thus is an ideal candidate to detect the presence of optical brighteners in surface waters. Engineers simply leave the tampon dangling in a stream for three days—insert your own adolescent joke here—then shine a black light on it to see if it glows more than a fresh-from-the-box tampon. The Sheffield University team have tested tampons in the laboratory and in the field, and so far they’ve passed with flying colors, correctly pinpointing a group of houses that were discharging sewage into the environment.

The tampon solution demonstrates that resourcefulness, not necessarily big investment, can address some of our most pressing problems. Might it also suggest that we need more women in science? It took men an awfully long time to come up with this idea.