Chemicals in rivers; England’s aquatic life threatened by a cocktail of hazardous substances
Research shows that the chemical mixtures in our rivers exacerbate the harmful effects of the individual hazardous substances, so the actual risks to our aquatic environments could be underestimated.
06/02/24
Blog
Monitoring of our rivers shows that aquatic life is often exposed to a mixture of hazardous substances in its natural environment, including industrial chemicals, pesticides, hydrocarbons, personal care products and pharmaceuticals. Often, just a single one of these chemicals can have negative impacts upon fish, invertebrates and other river life, affecting their growth and reproduction for example. However, research has shown that where a mixture of chemicals exists, their effects can combine, reinforcing and augmenting their toxicity and, therefore, the detrimental impacts on aquatic life. Because of these chemical mixtures, or cocktails, the actual risks to our aquatic environments could be underestimated. This is because, unfortunately, under current chemical legislation, hazardous substances are tested and their risk assessed as single entities, not as the mixtures in which they occur in the environment.
Recent analysis of Environment Agency datasets by The Rivers Trust and Wildlife and Countryside Link has quantified the prevalence of five chemical cocktails known to be toxic to aquatic life (see Figure ). Within these cocktails, the presence of six different chemicals was explored: four forever chemicals (PFOS, PFOA, PFBS and PFHxS), the pesticide 2,4-D, and the commonly used painkiller ibuprofen. In specific combinations, these chemicals are known to have increased harmful impacts on a range of species including amphibians, fish, insects, nitrogen-fixing bacteria and algae.
Across England, at least one of the cocktails was found in 814 river and lake sites (out of 1,006 sites with data – 81 per cent) and in 805 groundwater sites (out of 1,086 sites with data – 74 per cent). Around 54 per cent of these sites contained three or more of the five harmful chemical cocktails investigated. Moreover, up to 101 chemicals were identified in river samples, with sites along the rivers Mersey, Stour, Colne, Thames, Trent, Yare, Irwell, Medway, Humber and Avon among those containing the highest number of chemicals.
This, and plenty of other evidence shows us that chemical mixtures are commonplace in our rivers and that we need new legislation to address them, for example, through the application of mixture assessment factors in the determination of safe levels.
Rob Collins,
Director of Policy and Science
Figure: River, lake and pond sites in England where one or more of the five chemical cocktails were found. Derived from Environment Agency semi-quantitative data. Compounds included in these known harmful mixtures were ibuprofen, per-fluorooctanoic acid (PFOA), 2,4-Dichlorophenoxyacetic acid (2,4-D), per-fluorooctane sulfonate (PFOS), per-fluorobutane sulfonate (PFBS) and per-fluorohexane sulfonic acid (PFHxS). (© Environment Agency)