Human pharmaceutical and personal care products in the streams of an urbanizing watershed: Evidence of nonpoint source inputs

Concern is growing about the widespread occurrence of human pharmaceutical and personal care products (PPCPs) in streams.  Wastewater treatment plants (WWTPs) are believed to be the source of human PPCPs to streams, although the potential for nonpoint sources of these compounds has not been investigated.  Using data collected from streams in an urbanizing watershed in south-central Indiana, I show that nonpoint sources of human PPCPs were common and at times exceeded inputs from the WWTP in the watershed.  Concentrations were usually in the ng/L range, and compounds with the largest nonpoint sources included acetaminophen, caffeine, cotinine (nicotine metabolite), ibuprofen, and to a lesser extent sulfamethoxazole (antibiotic) and DEET.  Carbamazepine (anticonvulsant), triclosan (antibiotic), and trimethoprim (antibiotic) occurred in the WWTP effluent and in the stream downstream of the WWTP but did not occur in sites upstream of the WWTP.  Precipitation in the previous 24 hours, rather than stream discharge, was the best indicator of PPCP concentrations and loads.  Following precipitation, 50-75% of the total PPCP load downstream from the WWTP originated from nonpoint sources.  Even moderate rainfall (<20 mm) resulted in large nonpoint inputs of PPCPs, suggesting these compounds are a frequent and ubiquitous stressor for urban and suburban streams.