Background
Pharmaceuticals are indispensable to a healthy society and their use is among the most significant drivers of the increased life expectancy observed over the last 2 centuries. As with any chemical we use on a day to day basis, pharmaceuticals can reach the environment throughout their lifecycle. This includes via their manufacture (e.g., improper treatment of factory effluent), their use (e.g., incomplete metabolism and treatment of sewage), and disposal (e.g., via landfill leachate) often entering aquatic ecosystems. As environmental contaminants (typically at ng/L to μg/L concentrations), many pharmaceuticals have known ecotoxic effects on exposed organisms, often via interaction with highly conserved molecular receptors. These effects include behavioural changes, reproductive dysfunction, physiological alterations, selection of antimicrobial resistance, among others.
Despite nearly 30 years of research, relatively little is known regarding the global distribution and drivers of pharmaceutical contamination of aquatic environments. This is particularly evident for low to middle income countries (LMICs) and regions other than North America and Western Europe. Additionally, it is often, at least partially driven by a lack of the complex and expensive analytical infrastructure required for detection of pharmaceuticals in environmental matrices.
Pharmaceuticals are typically quantified in water using high pressure liquid chromatography tandem mass spectrometry (HPLC-MS/MS). Traditionally this involved collecting a large sample (several hundred mL) and pretreatment using filtration and pre-concentration measures. However, recent advancements in the sensitivity of mass spectrometers has allowed small (0.1mL) direct injection of water to resolve environmentally-relevant concentrations of pharmaceuticals. Taking advantage of increased analytical sensitivity, the Global Monitoring of Pharmaceuticals Project partnered with the United States Geological Survey to create and validate a miniaturised sample collection kit. The handheld kit contains all of the materials a user needs to collect up to 10 water samples using harmonised techniques and quality controls. Critically, the samples can be shipped via air and reach almost any location globally within 24hr. This ensures minimal sample degradation between the field and a centralised lab for analysis using a single analytical method.
The Global Monitoring of Pharmaceuticals Study leveraged this novel sample collection technique with aims to (a) expand the spatial distribution of pharmaceutical monitoring data, particularly in LMICs, (b) determine potential drivers of pharmaceutical pollution globally, and (c) identify potential ecotoxicity hotspots globally. It included 1,052 samples from 258 rivers across 104 countries of all continents, representing the pharmaceutical ‘fingerprint’ of nearly a half billion people on their surrounding environment. Highest cumulative concentrations were observed in sub-Saharan Africa, south Asia, and South America. The most contaminated sites were in LMICs and were associated with areas with poor wastewater and waste management infrastructure and pharmaceutical manufacturing. Of the 61 monitored pharmaceuticals studied, 53 were detected with carbamazepine being the most frequently detected chemical (62% detection frequency). The most polluted sampling site worldwide was located in the Rio Seke (La Paz, Bolivia) and had a cumulative pharmaceutical concentration of 297µg/L, almost entirely dominated by paracetamol. For comparison, that's a 115 times higher pharmaceutical concentration than in the East River of New York City. Concentrations of at least one pharmaceutical were above levels which may be toxic to algae, fish or daphnia at a quarter of monitored sites worldwide. Similarly, levels of antimicrobial pharmaceuticals were above levels thought to be protective of antimicrobial resistance (AMR) selection at 195 locations (19% of studied sites), predominately in sub-Saharan Africa and southern Asia. This one study presents data from more countries around the world than the entire scientific community was previously aware of: 36 new countries to be precise where only 75 had ever been studied before.
Recorded Lecture
John Wilkinson from the University of York talks about the global pharmaceutical monitoring project.
Key Reading
Bouzas-Monroy A, et al. (2022) Assessment of the Potential Ecotoxicological Effects of Pharmaceuticals in the World's Rivers. Environ Toxicol Chem. 41(8):2008-2020. https://doi.org/10.1002/etc.5355
Lis, S. et al., (2022) Antibiotics in Global Rivers. National Science Open 1(2): 20220029. https://doi.org/10.1360/nso/20220029
UBA (2024) Entry and occurrence of human pharmaceuticals in the environment.
UBA (2024) Database - Pharmaceuticals in the environment.
Wilkinson JL, et al (2022). Pharmaceutical pollution of the world's rivers. Proc Natl Acad Sci U S A. 119(8):e2113947119. https://doi.org/10.1073/pnas.211394711