Study found very high chemical pollution levels in two UK harbours

A study conducted by researchers from Brunel University, the University of Portsmouth, and Imperial College London has found increased levels of pollution in the waters of two UK harbours. The two harbours are Chichester and Langstone, on the south coast of England, which are home to sites of special scientific interest (SSSI). Analysing water samples from both harbours, the research team discovered significant traces of over 100 different pharmaceutical substances, pesticides, and illegal drugs. Moreover, some of these substances increased by over 100-fold after rainy days, which led to combined sewer overflows (CSOs) into the harbours. Dr Thomas Miller, from Brunel University, said that such an increase threatens aquatic wildlife in the special scientific interest areas. The most dangerous chemicals in the water were insecticides used in pet flea and tick treatments. However, researchers also detected the presence of 1,3-diphenyl guanidine, which is used in rubber production and could indicate pollution from tyre-wear particles and road run-off after rainfall events.
The study was conducted after the Environmental Agency reported that storm overflows spilled high levels of sewage into England’s rivers, lakes, and coast sites in 2024. Lead researcher Jasmin Uhlhorn, from Brunel University, said that the work underlines the complexity of chemical mixtures in coastal water systems and highlights the need for more comprehensive monitoring to investigate their sources. The findings also suggest that the real risk of chemical mixtures may be underestimated, particularly for aquatic wildlife. Commenting on the study, Professor Alex Ford, from the University of Portsmouth, observed that the impact of contaminants on coastal waters is yet to be determined, but it is clear from the data that the discharge of untreated sewage during storm events increases their presence. Clean Harbours Partnership, who collaborated with the research team, expressed concern over the detection of “a large cocktail of chemicals” on coastal sites and said it would continue to push for better monitoring of protected marine habitats.