Chemical contamination and the food chain
Contamination of rivers and oceans with persistent chemicals and heavy metals leads to poisoning and bioaccumulation in some species (e.g. higher concentrations in those at the top of the food chain such as fish eaten by humans). Substances dumped into water include heavy metals (mercury, arsenic, copper, iron and lead), pharmaceutical drugs and active ingredients in daily-use products (household and personal care). For example, the combustion of coal can lead to mercury pollution in water. The concentration of this neurotoxin, methylmercury, in tissues intensifies as it moves up the food chain. Fishes such as tuna and striped bass have been found with tissues with over 10 million times greater concentrations of methylmercury than the surrounding water. High levels of dietary exposure to fish contaminated with methylmercury increases the risk of fetal anomalies, cardiovascular diseases, and dementia in adults. Many countries around the world have issued advisories to restrict fish consumption to limit mercury toxicity. For example in the UK, it is advised to eat no more than two portions (≈280g) of small fish a week, and preferably avoid predatory fishes.
UK coastal litter and pharmaceutical pollution
In the UK, coastal litter mainly consists of fishing and sewage-related debris (20%), cigarette butts (18%) and other plastic waste including cups, bottles, cotton buds, crisp packets and shopping bags (12%). Microplastics in waterways, produced from primary or secondary sources or due to fragmentation of microplastics, have become a serious environmental and health hazard. Pharmaceutical products including antibiotics have been found in high concentrations in effluents of 13% of sewage treatment plants and waterways in the UK. Little is known about the environmental risk of the majority of medications currently in use. There is evidence of toxicological effects in animals due to the biologically active components dumped into water bodies; for example, oral contraceptives have led to the feminisation of male fishes and there is evidence of antimicrobial resistance linked to the discharge of antibiotics. The most effective strategy to prevent the disposal of pharmaceuticals in waterways is through cross-sectoral, multi-agency systems approaches, such as Scotland’s One Health Breakthrough partnership.
Our Recommendation
This requires a whole systems approach with investment in research to measure the ecological footprint of medicines that enables prescribers and patients to make environmentally informed choices. This generated data will help reduce harmful impacts by preventing the release of pharmaceuticals in water bodies through proper regulation and governance.