A pharmaceutical is a molecule with medicinal properties that is manufactured to treat, diagnose, cure, or prevent disease. Pharmaceutical prescribing is now the most common medical intervention in modern healthcare. This is in response to growing and aging populations, new technological advances, pharmaceutical availability and also the “pill for every ill” culture, which has become a common theme in today’s modern society.
According to the Scottish NHS, pharmaceutical prescribing rates in Scotland have increased by approx. 40% over the past 15 years, with more than 103 million pharmaceutical items dispensed in 2018-2019 (link). Total medicines costs across hospital and community prescribing are approximately £1.8 billion each year. Over-the-counter sales are also a significant route by which patients may privately attain pharmaceutical drugs, and UK sales reached £2.56 billion in 2017 (link).
As a result of this extensive use, these compounds enter waste streams in large quantities, either following ingestion and excretion, or direct disposal. After administration, pharmaceutical compounds are metabolised and excreted in urine and faeces. Sometimes the compounds undergo minimal metabolism in the body, and are excreted in an unchanged form. Additional activity, such as washing off topically applied medical creams, and improper disposal by flushing down the sink or toilet, adds to this.
Wastewater from homes, businesses, manufacturers, and hospitals is treated at municipal wastewater treatment plants (WWTPs). However, WWTPs are unable to completely eliminate pharmaceuticals from wastewater, and pharmaceutical removal and behaviour during treatment is not fully understood (link). Pharmaceuticals therefore have a direct pathway into the environment when final effluent is discharged from the WWTP, where the environmental effects are largely unknown.
However, pharmaceuticals are biologically active compounds, and can elicit specific responses in organisms even at low concentrations (i.e., the low levels which may occur in the environment). Ecotoxicological effects have been reported in laboratory-based studies and the environment, including:
- Feminisation of male fish (link and link)
- Reproductive changes in wild bivalves (link)
- Physiological changes in amphibians (link)
- Behavioural changes in crustacean spawning (link and link), and fish migration (link)
- Assistance in the spread of antimicrobial resistance (AMR) in bacteria (link and link)
- Potential contamination of raw water sources (link and link and link)
Pharmaceuticals have been widely detected in water around the world, including surface water and ground water. A literature review database of monitoring studies between 1987-2013, identified more than 630 compounds in 71 countries around the world (link). Data on the environmental presence of pharmaceuticals varies by location, with monitoring limited or non-existent in low-income, developing countries. Additionally, this varies by geographical region (rural or urban). In the UK, knowledge gaps exist on pharmaceutical presence in the Scottish Highlands and Islands (link).
Rural regions, such as the Highlands of Scotland, may face challenges related to wastewater management and environmental pollution, as wastewater is generally treated at small, less advanced WWTPs. These WWTPs may struggle to adequately eliminate pharmaceutical compounds as populations grow, wastewater volumes increase, and pharmaceutical usage continues to rise. The combined effect of these factors in the face of climate change and unusual weather patterns also adds further uncertainty to the potential risk of pharmaceutical pollution on water quality and environmental health.