Pharmaceuticals turning up in streams and rivers have made headlines in recent years. Now for the first time in the U.S., researchers have shown that such drugs may come directly from plants that manufacture them. Research published in Environmental Science & Technology (DOI 10.1021/es100356f) documents that treated sewage effluent from drugmakers can deliver to streams concentrations of painkillers that are as much as 1,000 times higher than levels in effluent from other sewage plants.
Until recently, scientists have assumed that the primary source of drugs in rivers was excretion by humans. Although the federal government does not regulate discharges of pharmaceutical ingredients, industry scientists have argued that tight control of production processes and the great value of the drugs would ensure that only minor amounts of active substances would escape the factories, says Joakim Larsson, an environmental scientist at the University of Gothenburg.
But in 2007, Larsson found that a treatment plant in India that receives drug factory waste was discharging as much as 31 mg/L of antibiotics in effluent, a concentration that is orders of magnitude higher than is typically found in U.S. waste water. He found the antibiotic ciprofloxacin at concentrations higher than recommended human blood levels.
To begin to check whether the same issues might occur at the nearly 3,000 drug manufacturing facilities in the U.S., researchers from the U.S. Geological Survey (USGS) compared effluent from two New York state treatment plants serving drug manufacturers to 24 treatment plants not receiving pharmaceutical-plant waste in 12 states. Referring to the plants serving drugmakers, Dana Kolpin, a research hydrologist at USGS and a coauthor of the new study, says: “When we scanned the effluent samples using capillary gas chromatography/mass spectrometry, we noticed large peaks due to unknown substances.” Comparing GC/MS scans of known drugs to scans of the unknown samples allowed the researchers to determine that the unknowns were seven opiates and muscle relaxants that are among the most frequently prescribed medications in the U.S., he says.
Effluent samples from across the country showed evidence of the drugs, but concentrations were all less than 1 µg/L. However, the New York plants that serve drugmakers released the seven painkillers in concentrations ranging from 3.4µg/L to 3,800 µg/L. The highest concentration was for the muscle relaxant metaxalone.
“The concentrations coming out of effluent are much higher than we would ever have thought,” says Patrick Phillips, a USGS hydrologist and lead author of the study.
The researchers also detected the seven drugs in a drinking-water reservoir 30 km downstream of one of the New York plants.
Despite the different conditions and stringent regulations in the U.S., says Christian Daughton, an environmental toxicologist at the EPA, Phillips’s and Kolpin’s study found broadly similar results to Larsson’s study in India. However, Daughton cautions against drawing nationwide conclusions from sampling only two plants receiving pharmaceutical waste.
Still, Chris Metcalfe, an environmental toxicologist at Trent University, thinks the research should change views of drug manufacturing. “Hopefully, this study will lead to pharmaceutical companies taking ownership of their discharges,” he says.