Once absorbed by the body, these chemicals—known as endocrine disruptors—interfere with normal bodily functions either by mimicking or blocking the production of hormones.
Experts say endocrine disruptors are found in pesticides, pharmaceuticals, fumigants, and fungicides. Municipal and domestic sewage and wastewater from farms and industries might be routing these chemicals into the water supply.
The presence of such chemicals is not unique to the Potomac. The pollutants have previously been documented in bodies of water in other parts of the United States as well as in Europe.
Scientists have also found reproductive problems in fish and birds in habitats along the U.S. Great Lakes. Similarly, declining alligator populations in Florida's Lake Apopka have been linked to synthetic chemicals that hinder reproduction.
Chambers says the USGS is analyzing data from last year and is planning to release a more detailed report later this year. The next report will try to make a definitive link between these chemicals and their effects on the environment.
"Currently many of these compounds have not been well researched for their environmental characteristics, how they are taken up by living organisms, and how they can be removed from streams," he added.
Dana Kolpin is a USGS research hydrologist and director of the agency's Emerging Contaminants Project. He reviewed Chambers' study but is not connected with it.
"This is the first step to understanding a very complex issue," Kolpin said.
"We need to understand the cocktail of compounds that are in the environment and whether there are certain bad actors that are causing feminization of males—and what it means for humans [who use this water]."
"It is critical to know where the sources are, how the compounds are being transported, and which ones are being degraded. What happens to them [after they enter the river] is the million-dollar question."
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