Crowds gathering at rivers and streams during Labor Day weekend do more than just enjoy the water. They temporarily add chemicals and tiny organisms to the local waterways, according to new research from Johns Hopkins University.
During the Labor Day weekend, people flock to rivers and streams not only to cool off but also to introduce various chemicals and microorganisms into these waters, as shown by new research from Johns Hopkins University.
The study, released today in ACS ES&T Water, is the first comprehensive evaluation of how recreational activities affect streams. The results also shed light on the substances and chemicals present when popular swimming locations become crowded.
Lead author Carsten Prasse, an assistant professor of environmental health and engineering at Johns Hopkins, explained, “Residues from sunscreens, shampoos, and other home products can wash into the water. This goes for everyone around you as well. The chemicals you are in contact with are influenced by your fellow swimmers, creating a sort of chemical ‘soup’.”
Prasse and his colleagues took water samples from Clear Creek, a favorite tubing destination for local residents in Golden, Colorado, over the 2022 Labor Day weekend. They collected one sample upstream of the recreation area and another downstream where people exit the water.
Using advanced analytical techniques, the researchers detected remnants of lidocaine, acetaminophen, and other pharmaceuticals, along with chemicals from cleaning products, personal care items, and pet care products in the downstream samples. Additionally, they found ingredients from sunscreens and substances leaching from plastics, as well as human gut microbes.
However, two days after Labor Day, water samples revealed that the creek had returned to its previous condition, according to the researchers.
“The alterations in water quality are temporary, but they are still important,” remarked Noor Hamdan, the first author and a doctoral graduate from Prasse’s lab. “Flowing water carries these compounds further downstream, which could have effects on plants and animals along the way.”
