TAMPONS may not be an obvious scientific tool, but university researchers have revealed how useful they are to check if water from baths, washing machines, sinks and showers is polluting rivers and streams.

And now the Friends of Bradford's Becks (FOBB) will be using the discovery to test if waterways are being polluted in the city.

The group's chairman, David Lerner, is a professor of environmental engineering at The University of Sheffield. He led a study which found the natural, untreated cotton in tampons readily absorbs optical brighteners commonly used in toilet paper, laundry detergents and shampoos, which glow under ultra-violet light.

The Faculty of Engineering researchers found when tampons are suspended in water contaminated by even very small amounts of detergents or sewage, they will pick up chemicals and glow under UV light.

The findings were today published in the Water and Environment Journal.

Professor Lerner said: "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.

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"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.

"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."

The study, funded through the Engineering and Physical Sciences Research Council (EPSRC), found when a tampon was dipped for just five seconds into a solution containing 0.01ml of detergent per litre of water - over 300 times more dilute than would be expected in a surface water pipe - optical brighteners could be identified immediately and were visible for 30 days.

The technique was then trialled in the field by suspending tampons for three days in 16 surface water outlets running into streams and rivers in Sheffield - nine of the tampons glowed under UV light.

With the help of Yorkshire Water, the team followed the pipe network back from four of the nine polluted outlets, dipping a tampon in at each manhole to see where the sewage was entering the system.

It could then narrow down the source of the pollutant to individual households.

Pro Lerner hopes to trial his method on a larger scale to identify all the sources of sewage pollution on Bradford Beck, working in partnership the University, Bradford Council, Yorkshire Water and the Environment Agency.

"The plan is first to do reconnaissance surveys with tampons of the watercourses to narrow down where the problems are occurring, then find the guilty outfalls and monitor those.

"The water utility will be invited to track down the households with misconnected drainage by working back up the drainage system," he said.