Many streams are at risk from pharmaceutical pollution
Traces of pain-relieving substances, diabetes drugs and allergy medicines are widespread in small streams across the Southeast, especially in urban zones like Raleigh, North Carolina, the U.S. Geological Survey found in a new study.
The USGS in 2014 sampled 59 small streams in portions of Alabama, Georgia, North Carolina, South Carolina and Virginia for 108 different pharmaceutical compounds and detected one or more pharmaceuticals in all 59 streams. The average number of pharmaceuticals detected in the streams was six.
The EPA is currently developing rules for regulating pharmaceutical pollution, but government watchdogs say the agency’s proposal is much to weak. Other studies have shown that the toxic cocktail of pharmaceutical remnants is already affecting basic stream health. From their, the chemicals are making their way up the food chain and have even turned up in remote Mexican cenotes.
Most wastewater treatment facilities aren’t equipped to remove these substances before the water is discharged back into streams and rivers, but the findings in the new study show there are other sources as well. Only 17 of the 59 streams have any reported wastewater discharges. The study was published in the the journal Environmental Science and Technology Letters.
“The widespread occurrence of pharmaceuticals in these small streams irrespective of wastewater discharges indicates the need for approaches for preventing pharmaceutical contamination that extend beyond effluent treatment,” said Paul Bradley, a USGS research hydrologist and the lead author of the study. “Sources of pharmaceuticals to these small streams likely include aging sewer infrastructure and leakage from septic systems.”
The most common pharmaceutical chemicals detected are:
- Metformin: Used to treat Type II diabetes, this chemical was detected in 89 percent of samples
- Lidocaine: Used as a pain reliever, this chemical was detected in 38 percent of samples
- Acetaminophen: Used as a pain reliever, this chemical was detected in 36 percent of samples
- Carbamazepine: Used to treat seizures, this chemical was detected in 28 percent of samples
- Fexofenadine: Used as an anti-histamine, this chemical was detected in 23 percent of samples
- Tramadol: An opioid pain reliever, this chemical was detected in 22 percent of samples
Although much uncertainty remains as to how pharmaceuticals affect aquatic organisms, some adverse effects have been documented. Antibiotic/antibacterial contaminants – detected in at least 20 percent of streams – can affect aquatic microbial communities, altering the base of the food web. Antihistamines, frequently detected in this study, affect neurotransmitters for many aquatic insects. And metformin, nearly ubiquitous in the streams studied, can affect the reproductive health of fish.
The chemicals with the highest concentrations are those listed above, but none exceeded human health benchmarks. In addition to the individual chemicals listed, the two groups of compounds most frequently detected were nicotine-related compounds (71 percent of samples) and caffeine-related compounds (detected in 49 percent of samples).
This study is one of several regional stream-quality assessments by the USGS National Water Quality Assessment (NAWQA) Project. Findings will provide the public and policy-makers with information regarding which human and natural factors are the most critical in affecting stream quality. Regions studied include the Midwest (2013), Southeast (2014) and the Pacific Northwest (2015), and planning is underway for studies in the Northeast (2016) and California (2017).
Support for this work was provided by the USGS National Water Quality Program’s NAWQA Project. Additional support was provided by the USGS Toxic Substances Hydrology Program.