Modern pesticides found in UK rivers could pose risk to aquatic life

Pesticide pollution can be extremely damaging to the environment. Pesticides are intrinsically toxic chemicals capable of inflicting a wide range of effects on wildlife, which can in turn cause lasting damage to wildlife populations and ecosystems. Despite these concerns, more research needs to be undertaken to understand the level of pesticide pollution in English rivers.

New research has assessed the distribution of current-use pesticides, which are currently on the market and being used in various applications, including agriculture. The research also evaluated the pollution by such pesticides in the waters and sediments of two English rivers; the River Tone in Somerset, which runs through Taunton, and the River Wensum in Norfolk, which runs through Norwich. The data generated by the study represents one of the most comprehensive assessments of pesticides in any English river catchment to date and is widely applicable to other river catchments across the UK.

Water, sediments, fish and invertebrates were collected along the two rivers and analysed for 52 pesticides. The study, undertaken by BGS in collaboration with the University of Nottingham, found that the veterinary pesticide fipronil was measured at high concentrations. Fipronil is commonly used by vets as an anti-flea treatment for dogs and likely gets into our rivers by dogs accessing these waterways. In addition, propiconazole (a systemic fungicide commonly used in agriculture) was found at elevated concentrations in sediments from the rivers Tone and Wensum.

Neonicotinoids, a group of neuro-active insecticides, are used in agriculture to help prevent crops from being eaten by pests and were found in both of the rivers. At one-third of the sites sampled, the level of neonicotinoids exceeded the chronic threshold for aquatic invertebrates, meaning they will be affecting the health of these organisms.

Modern chemical pesticides have positive applications, such as veterinary medicines helping prevent fleas in domestic pets and in UK agriculture where herbicides, insecticides and fungicides can help prevent food shortages by protecting crops from various pests.

However, our research has highlighted that these pesticides are now present in English rivers and could potentially pose threats to the local wildlife. To help mitigate the risk to ecosystem health, additional protective measures are needed to promote more environmentally sustainable practices, alongside the introduction of stricter regulation around the most high-risk pesticides to help protect our rivers from further impact.

Christopher Vane, head of BGS Organic Geochemistry.

The research has highlighted that further studies need to be completed in order to determine the effects that modern pesticides could have on ecosystems of rivers. BGS will also complete additional research in other countries over the next few years, which will continue to assess which pesticides are present in rivers.

The research paper, ‘Widespread pesticide pollution in two English river catchments of contrasting land-use: from sediments to fish’, is available to read.