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A new study has found traces of the widely used metformin diabetes drug and other medicines in dozens of streams throughout the Southeastern United States. But the findings suggest the cause was generally unrelated to discharges from wastewater treatment facilities, which are usually considered to be the likeliest source of contaminants.

The survey of 59 streams found an average of six different pharmaceuticals. Besides metformin, which appeared in 89 percent of the samples and 97 percent of the sample sites, researchers found traces of three different pain relievers, including the tramadol opioid painkiller; the carbamazepine anti-seizure drug; and the Allegra antihistamine. These meds were found in 22 percent to 28 percent of the samples.

Moreover, the analysis, which was published in Environmental Science & Technology, detected pharmaceuticals at more than 10 percent of the sample sites at concentrations that would be expected to affect aquatic life. While pharmaceuticals are often detected in bodies of water, the analysis noted that only 17 of the 59 streams in which samples were taken have any reported wastewater discharges.


The researchers who conducted the survey — which looked for 108 different pharmaceuticals in Alabama, Georgia, North Carolina, South Carolina, and Virginia — say the findings indicate a broad-scale need for mitigation, because medicines are finding their way into surface water through previously unknown or overlooked routes.

“We know that wastewater treatment facilities are a significant source” of pharmaceuticals, said Paul Bradley, a research ecologist and hydrologist at the US Geological Survey and the lead author of the analysis. “But more than 70 percent of sites didn’t have a facility, which means the contaminants are making it through the environment through different mechanisms.”


The findings come amid growing  clamor among some local governments – notably, in California – to require drug makers to pay for so-called take back programs for unused prescription medicines. The idea is driven in part by the cost of disposal, worries about leftover prescription painkillers getting into the wrong hands, and water pollution.

So how are medicines finding their way into streams? Bradley posited one culprit is urban development, such as rainfall runoff from parking lots and roads. Another reason, he explained, may be leakage from subsurface sources, such as septic distribution lines that are connected to wastewater treatment facilities. “In many cities,” he said, “the infrastructure is old.”

Such findings underscore concerns about the effect of pharmaceuticals in surface water. The USGS noted that, while uncertainty remains about the effects on aquatic organisms, antibiotics can affect aquatic microbial communities, which alters the base of the food web. Metformin can affect the reproductive health of fish, and antihistamines affect neurotransmitters for many aquatic insects.

The analysis noted that metformin can pass through the human body essentially unchanged. Moreover, the drug is “poorly removed by conventional and many advanced wastewater treatment technologies, and is considered environmentally recalcitrant.”

This is only the latest analysis to highlight the presence of pharmaceuticals in surface water. Last month, a published study found low levels of various medicines — antibiotics, antihistamines, and pain relievers — as well as carcinogenic chemicals and mercury in oysters that grow in two Oregon bays.

“This is a societal concern,” said Bradley. “In Europe, there’s more pressure for industry to prove its compounds don’t stick around in the environment. We’re a little behind in the United States.”

  • Not surprising. The widespread practice of spreading “free” sewage sludge on agricultural fields and composting and bagging the stuff to sell to suburbanites puts whole lot of unknown compounds out there to alter the complex community of bacteria, fungi, algae, nematodes, worms, insects, etc.that interact to alter the functions of the soils in which we grow our food or to be ingested by us in our drinking water. As an organic farmer I strive to protect the integrity of our soils by just saying no and carefully studying any amendments (e.g.lime,fertilizers, etc) we might make to our soils. We collect rainwater extensively and although it may contain pollutants from the air at least it doesn’t have pharmaceuticals.

  • All of the cited drugs are widely used generics. Good luck with the drug company take back programs. For example, metformin is a multisource generic, made by at least 60 companies.

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