Home Chemistry Tampons absorb contaminates; help scientists track river pollution

Tampons absorb contaminates; help scientists track river pollution

Tampons are eminently useful items: They help with feminine issues, of course, but they’re also pretty darned handy for, say, stopping a nosebleed in a pinch. Now, scientists at the University of Sheffield have found a more novel use for the hygiene products: Identifying and tracking river pollution.

“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. Unfortunately, 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,” said Professor David Lerner.

So where to tampons come in? Simple – it’s their absorbancy. Anyone who’s used one (for any purpose) knows that simple cotton tampons are alarmingly absorbent. That applies not just to the liquid they’re in, but whatever’s in the liquid as well. The average home dumps all sorts of pollutants down the drain every day. Some of these, like toilet paper, laundry detergents and shampoos, contain substances called chemical brighteners – chemicals used to brighten whites and enhance colors. If you live in one of those million+ homes with incorrect plumbing, you may be flushing those chemicals into the groundwater.

The scientists found that the tampons are especially adept at identifying these chemical brighteners: When dipped into a solution containing 0.01ml of detergent per litre of water (more than 300 times more diluted than you’d expect to find in a groundwater pipe) for just five seconds, the tampon was able to absorb and identify it immediately,  and held on to the contaminant for more than 30 days.

How were scientists able to tell that the tampons had absorbed the chemicals? UV lights, colloquially known as “black-lights” in bars, clubs and college dorms around the world. When a tampon rich in chemical brightener is bathed in UV light, it glows in the dark like a white t-shirt at a rave.

Dropping a few tampons into manholes has significant advantages over current contaminant detection methods.

“Often the only way to be sure a house is misconnected is through a dye test – putting dye down a sink or toilet and seeing where the coloured water appears in the sewer,” says Professor Lerner. “It’s clearly impractical for water companies to do this for all the households they supply, but by working back from where pollution is identified and narrowing it down to a particular section of the network, the final step of identifying the source then becomes feasible.”

By contrast, by dipping tampons into manholes, Lerner and his crew were able to quickly isolate the potential sources in a contaminated groundwater network. Once the households were narrowed down, a visual inspection immediately revealed the culprit – a home with improperly installed sink and soil stacks.

Pollutants found in domestic waste water change the bacterial and invertebrate life in rivers, encouraging pollutant tolerant species and leading to the build-up of ‘sewage fungus’, which is visible as a grey lining to the river bed.