Quantifying the influence of climate change on pesticide risks in drinking water

Climate change can influence pesticide contamination and resulting human health risks due by altering weather conditions that drive pesticide fate and transport. However limited research has examined these effects, leaving regulatory frameworks and adaptation strategies unable to address future pesticide risks. This study develops a novel probabilistic model to quantify climate change impacts on pesticide-related human health risks under two different climate scenarios, using study locations in the north-east and south-west of Ireland. Results indicate that pesticide concentrations in drinking water are projected to exceed legal limits more frequently, and by greater amounts, under all climate scenarios, with associated health risks increasing by an average of 18 % under RCP 4.5 (2050) and 38 % under RCP8.5 (2100). The model results also indicate significant regional variation in health risk, with risk 48 % higher in the south-west than the north-east under baseline conditions. Climate change effects intensify these regional variances with risk up to 70 % higher under RCP4.5 (2050), and 85 % higher under RCP8.5 (2100). Despite these increases, overall pesticide human health risks are likely to remain low in Ireland under future climates. This study presents a probabilistic framework that may be applied internationally to quantify the impact of climate change on human health risk at a local-scale and may be adapted for different site conditions and climate projections to suit users' needs. This approach can inform future pesticide management programmes by identifying vulnerable areas and key pesticides under changing climate conditions, emphasizing the importance of incorporating climate change into pesticide risk mitigation and public health strategies.