Ironically enough, one male researcher from England used tampons to detect grey water contamination, or laundry system run off, that might be present in waterways. The tampons absorbed key signature chemicals that glow in the dark, making them easy to use and cheap. Moreover, it’s more reliable than consecrated and expensive methods.

Typically, each town or city has two separate sewage system. There’s one for all the waste you flush down the drain, toilet, washing machine or dishwasher, and another for rainwater that gets collected from places like  roofs, paved roads, parking lots etc. This latter kind of sewer, called a storm sewer, is important to keep clean and clear of the sanitary sewer since it’s directly drained into streams or rivers. Sometimes the two mix, however, for various reasons. Someone might have had the bright idea to make his own home plumbing and make a mess of it. Some might intentionally contaminate the storm water.

Whatever’s the case, it’s important to locate waste in waterways as soon as possible to minimize damage. Generally, environmental agencies around the world have a couple of techniques at their disposal. These are cumbersome however, to say the least. For instance, spectrometers are widely used to analyze for contaminants, but these are expensive and require highly trained personnel to use. A newer grey water detection method involves inserting fibre optic cables but these cost 13USD per meter.

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Inspired by the Environmental Protection Agency in the US who used cotton pads to monitor pollution, two Yorkshire researchers decided to test the method locally using a much more handy and readily available solution: tampons. But since when are tampons fitted with spectrometers? This requires a bit of background. Ever wonder how detergents make your clothes “whither than white” and get rid of yellow stains? Well, it all involves a clever trick; hint: the yellow doesn’t really go away.  To make clothes appear whiter, detergent manufacturers put an additive called an ‘optical brightener‘ that absorbs into the fabric and remains absorbed after the laundry is finished. There are many such molecules that act like OBs (read optical brighter, not the tampon brand…), but they all seem to do the same thing – they fluoresce. When exposed to UV light, the chemicals emit blue light that helps cancel out the yellow tinge and tricks the eye into thinking the clothes are more white than they really are. Clever indeed, but oh so tricky.

Anyway, the OBs can be used as indicators for gray water pollution. If these are found in a storm sewer, then it means water from washing machines is leaking through somewhere. Once you detect the leak, it’s all a matter of tracing the plumbing to the source.  Professor David Lerner, a professor of environmental engineering at the University of Sheffield and colleagues placed tampons, tied to bamboo poles, in 16 surface water sewers and left them in place for three days. They then took the samples and put them under a black light. Contaminated samples glow bright in the dark because of the OBs. They found that even in small concentrations, the contaminated tampons glowed.

“You do get people looking at you strangely, but the tampon is not that obvious,” said Professor David Lerner, a professor of environmental engineering at the University of Sheffield.

“It’s cheap, it’s easy and it does the detective work,” he added.

The method works so well that the biggest problem the researchers faced were well-intentioned neighbors who misidentified the tampons for garbage and threw them in the bin. Because anyone can use a tampon, the researchers propose a sort of citizen science project where community members are invited to sample their local sewers and test for results themselves. If done right, in conjunction with an online app for instance, a nice networked map of storm water mishaps could be made – all at the fraction it currently costs to make.

“More than a million homes have their waste water incorrectly connected into the surface water network, which means their sewage is being discharged into a river, rather than going to a treatment plant.

“It’s very difficult to detect where this is happening, as the discharge is intermittent, can’t always be seen with the naked eye and existing tests are complex and expensive.

“The main difficulty with detecting sewage pollution by searching for optical brighteners is finding cotton that does not already contain these chemicals. That’s why tampons, being explicitly untreated, provide such a neat solution. Our new method may be unconventional – but it’s cheap and it works.”

Of course, more investigations are required to determine whether the method is reliable as it sounds. The results published in the Water and Environment Journal definitely promising though.