Image description: Colourful Oil Spill on Muddy Ground. Photo by Abdulrahman Abubakar / Pexels
The Royal Society has issued a stark warning about the risks posed by unregulated chemical mixtures in UK rivers, lakes, and coastal waters. Its latest report, Chemical mixtures in aquatic environments: understanding and preventing harm, argues that current regulatory frameworks are inadequate and fail to account for the cumulative effects of multiple pollutants.
As reported by the Royal Society, regulators typically assess individual chemicals in isolation, often under laboratory conditions. However, in real-world environments, these substances interact in complex ways, potentially causing greater harm than the sum of their parts. The report calls for a “pragmatic, yet precautionary” approach to managing chemical mixture risks, including tighter controls on releases and improved monitoring technologies.
Professor Michael Depledge, co-chair of the report, stated that “we have been blind to the combined harmful effects of mixtures of these chemicals in aquatic ecosystems,” and emphasised the urgency of equipping regulators with new tools and expertise to protect ecosystems and public health.
Less data available for chemical cocktails in the marine environment
The report highlights emerging contaminants such as PFAS, pharmaceuticals, and plasticisers, which are not routinely monitored but may disrupt hormonal cycles, fertility, and behaviour in aquatic species. Preliminary analysis by the UK Centre for Ecology and Hydrology found that the highest mixture risks currently come from metal pollutants and polycyclic aromatic hydrocarbons (PAHs), though data coverage remains limited – 85% of UK monitoring focuses on rivers, with little attention to estuaries and marine environments.
Professor Louise Heathwaite, also co-chair, noted that “chemical mixtures have long been considered an intractable problem,” but argued that the UK now has an opportunity to lead in developing innovative regulatory responses.
Investment needed to monitor growing threat
The report recommends investing in environmental DNA and machine learning to improve detection and analysis, alongside expanded training for environmental toxicologists. It also urges alignment with the UK’s Environmental Improvement Plan and calls for collaboration with EU partners exploring similar reforms.
With over 350,000 chemicals in global production and chemical output expected to triple by 2050, the Royal Society warns that failure to act could undermine biodiversity and human health. The findings add pressure on policymakers to strengthen environmental protections and modernise regulatory systems.