Tampons are cheap and highly absorbent, which makes them the perfect tool for testing rivers for pollution. Tampons submerged in contaminated water shine blue under ultraviolet light because of the brightening chemicals they have sucked in, researchers report March 30 in the Water and Environment Journal.
Rivers can become polluted when wastewater from washing machines, sinks and showers (and rarely toilets) — which should flow into sewers that lead to treatment plants — accidentally connects to sewers for rainwater instead. Untreated wastewater is laced with chemical brighteners from laundry detergent and cleaning products.
“A tampon is one of the few things you can buy that is not pretreated with optical brighteners,” says coauthor David Lerner, an environmental engineer at the University of Sheffield in England. That makes them a perfect product in which to see brighteners from polluted water.
Lerner and his team field-tested tampons in 16 sewer outlets near campus, all of which had a reputation for pollution. The engineers soaked the tampons in the water for a day before shining UV light on them. Tampons from nine of the sites absorbed enough chemical pollution to glow, signaling misconnected drains.