A New Tool to Detect River Pollution: Glowing Tampons

​We know that our rivers are polluted, but it's harder to know exactly where that pollution is coming from. Enter a new tool that's proven perfect for the job: tampons.

Environmental engineers David Lerner and David Chandler from the University of Sheffield present the first UK trial of the "inexpensive, simple, passive sampler" in a new paper in the Water and Environment Journal.

They were looking for a particular cause of pollution: misconnected drainage. In a phone call, Lerner explained that most houses have two drainage networks—one to take sewage and waste from appliances like washing machines to the sewer network, and one to take clean water, such as rainfall from drainpipes, back to the river system. "What happens is, as houses get altered and redeveloped, or people make mistakes, they start connecting the dirty water into the clean water system," he explained.

So where do the tampons come in? The researchers used them to detect where this pollution is happening.

One thing to look for to detect misconnected drains is optical brighteners (OBs)—chemicals used in detergents, toilet paper, and cleaning products that glow under UV light. But in order to pick up the OBs, you need to use something that doesn't contain any in the first place. Tampons, which naturally avoid containing too many chemicals, are perfect.

"They're one of the very few cotton materials you can buy that has no optical brighteners on them," explained Lerner.

The researchers fixed tampons along sewers, where they absorbed the water. They were left for three days and then checked under UV light: a fluorescing tampon signalled OB pollution. By following the tampon trail, the researchers could pinpoint which section of sewer had a problem by picking out the point that had glowing tampons downstream but not upstream. From there, they had a much smaller group of houses to check for misconnected drains.

Tampons also offer other conveniences. "They come with a nice little string attached so we can tie them onto something; they come individually packaged so we know they're clean—they're absolutely wonderful, almost as if they were designed for a monitoring device," said Lerner.

The initial point of the work was to identify a site to do field work on the ecological impact of this kind of pollution, but Lerner's now hoping to expand the method on a much bigger scale with a Bradford co​mmunity group.

Estimates su​ggest as many as 20 percent of homes could have something misconnected. This means all kinds of detergents and chemicals are getting into the rivers, threatening the ecosystem by killing off some species and providing environments for other undesirable species to grow.

The new method is not perfect—the tampons can get dirty so fluorescence can't be detected, and the paper reports that some were vandalized by the public. Additionally, as they only detect OBs, other pollution could be missed. But it's a good starting point, especially as the paper states that each "sampler" cost just 20p.

Lerner signed off with a clear message for those who aren't going out to play tampon detective: "Go and check whether your washing machine is going to the foul water or the clean water, and get it fixed."