Formatted Title
Pharmaceuticals in Surface Water: Extent and Sources of Contamination
Background/Objectives
Concern over the presence of pharmaceuticals in aquatic environments has been growing for over two decades. Because pharmaceuticals are designed to be biologically active, they can have very serious adverse effects on fish and wildlife and possibly on human health at part per trillion concentrations. Recent studies suggest that the spillover of antibiotics into surface water may be a significant factor in promoting antibiotic resistance in bacteria.
Reconnaissance studies focusing on pharmaceuticals and other contaminants of emerging concern initially focused on wastewater treatment plants (WWTPs) as the main source of pharmaceuticals to surface waters. This was reasonable since these chemicals are generally recalcitrant to biodegradation and WWTPs were not designed to remove them from the waste stream. However, other potential sources of pharmaceuticals to our surface waters remained relatively uninvestigated. In Minnesota, several large reconnaissance studies were conducted to understand 1) the extent and the magnitude of pharmaceutical contamination in the state’s rivers, streams, and lakes, 2) the role that different sources play in contributing these contaminants to aquatic environments, and 3) the trend of these contaminants in water over time.
Approach/Activities
Over 300 chemicals, including 184 pharmaceuticals, pharmaceutical metabolites, hormones, and illicit drugs, were tested in water samples that were collected in five large-scale probabilistic studies of lakes, rivers, and streams over a span of 10 years. Each of these studies consisted of 50 randomly selected locations across the state in conjunction with EPA’s National Aquatic Resources Study program. Rain, snow, and aerosol samples were also collected and analyzed to determine whether precipitation might contribute these contaminants to surface water. Fugacity analysis was performed to understand if contaminants might find their way into precipitation and atmospheric aerosols from WWTPs.
Results/Lessons Learned
Detections of pharmaceuticals in surface water included several antibiotics, antidepressants, anticonvulsants, heart medications, x-ray contrast agents, and hormones. These chemicals are detected across the state at very remote locations, including lakes with no development or exposure to wastewater, raising the question of how these chemical contaminants reach such locations. Testing of precipitation showed that antibiotics, x-ray contrast chemicals, anti-inflammatory medication and several other contaminants are present in snow, rain, and aerosols at concentrations that can account for the observed levels in surface water at some locations. Fugacity analysis suggests that WWTPs are not the only source of antibiotics and other contaminants to surface water. It is possible that land spreading of biosolids may play an important role in the movement of pharmaceuticals to the atmosphere and to precipitation. The results of these studies show that although WWTPs are a major source of pharmaceutical contamination to surface water, other sources likely play important roles as well, and will need to be addressed in efforts to mitigate pharmaceutical contamination of surface water.