Diagnosing down-the drain disposal of unused pharmaceuticals at a river catchment level: Unrecognized Sources of Environmental Contamination That Require Nontechnological Solutions

Problem: Down-the-drain disposal of pharmaceuticals remains an overlooked and unrecognised source of environmental contamination that requires non-technological ‘at-source’ solutions.  

The study: Monitoring of 31 pharmaceuticals over 7 days in 5 wastewater treatment plants (WWTPs) serving 5 cities in South West UK revealed down-the-drain co-disposal of 6 pharmaceuticals to three WWTPs (carbamazepine and propranolol in city A, sildenafil in city B and diltiazem, capecitabine and sertraline in city D), with one-off record co-disposal of estimated 253 pills=40g of carbamazepine and estimated 96 pills=4g of propranolol in city A accouting for their 10 and 3-fold respective increase in wastewater daily loads. Direct disposal of pharmaceuticals was found to affect efficiency of wastewater treatment. Estimated daily loads in receiving water downstream from a discharge point accounted for 13.8±3.4 g day^-1 and 2.1±0.2 g day^-1 of carbamazepine and propranolol respectively during ‘consumption only’ days and peaked at 20.9 g day^-1 (carbamazepine), 4.6 g day^-1 (propranolol) during ‘down-the-drain disposal’ days. Actions are needed to reduce down-the-drain disposal of pharmaceuticals.  

Conclusions: Our recent work indicated that down-the-drain disposal of pharmaceuticals doubled since the last study in 2005 which may be due to the lack of information and messaging that informs people to dispose of unused medicines at pharmacies. Media campaigns that inform the public of how to safely dispose medicines are key to improving rates of return and reducing pharmaceutical waste in the environment. The environment is a key motivator for returning unused medicines to a pharmacy and so messaging should highlight environmental risks associated with improper disposal.  

 

 

Paper(s): 

Kasprzyk-Hordern, B., K. Proctor, K. Jagadeesan, S. Watkins, R. Standerwick, R. Barden, and J. Barnett. 2021. “Diagnosing Down-the-Drain Disposal of Unused Pharmaceuticals at a River Catchment Level: Unrecognized Sources of Environmental Contamination That Require Nontechnological Solutions.”  Environ Sci Technol. doi: 10.1021/acs.est.1c01274. 

Petrie, B., J. Youdan, R. Barden, and B. Kasprzyk-Hordern. 2016. “New Framework To Diagnose the Direct Disposal of Prescribed Drugs in Wastewater – A Case Study of the Antidepressant Fluoxetine.”  Environ Sci Technol. doi: 10.1021/acs.est.6b00291. 

Watkins, S., J. Barnett, M. Standage, B. Kasprzyk-Hordern, and R. Barden. 2022. “Household disposal of pharmaceuticals: attitudes and risk perception in a UK sample.”  Journal of Material Cycles and Waste Management 24 (6):2455-2469. doi: 10.1007/s10163-022-01494-7. 

Partners: Wessex Water 

Funders: UKRI The support of Wessex Water Services Ltd and EPSRC Impact Acceleration Account (Project number: EP/ K503897/1 and EP/R51164X/1, ENTRUST IAA), Leverhulme Trust (Project No RPG-2013-297).