A study carried out at the University of Helsinki has uncovered evidence that the combination of climate change and chemical pollution poses a far greater threat to ecosystems and human health than previously understood.
Traditionally, research has focused on either climate change or chemical pollution in isolation, overlooking their combined effects. This oversight creates a blind spot in understanding the full scope of risks to ecosystems and human health.
"My research demonstrates that the concurrent stresses of heatwaves and chemical pollutants can harm species and disrupt ecosystems , alter food chains, and heighten the risk of human exposure to harmful chemicals through contaminated water and food," says Sabrina Roth, doctoral student at the Faculty of Biological and Environmental Sciences, University of Helsinki.
To explore this, Roth started by testing the impact of heatwaves and an everyday antibiotic on a single species of phytoplankton. She then moved to more complex experiments with a mixed-species planktonic community, studying how a common pesticide used in farming interacts with heat. Finally, she used computer models to predict how extreme weather events caused by climate change combined with chemical pollution could affect people, as an example, she used the Swedish population, by forecasting their exposure to chemicals through water, food, and air. This step-by-step approach highlights how climate change and chemical pollution together can impact everything from tiny organisms to entire ecosystems, and even human health.
Implications for industry and policy
Roth's doctoral thesis highlights a critical issue in industrial practices: safety tests for new chemicals typically do not account for the potential impacts of global climate change. A chemical deemed safe under normal conditions might become much more harmful when combined with extreme climate events like heatwaves. This research calls for more comprehensive regulations and testing protocols that address these combined impacts.
Moreover, Roth suggests that public awareness and changes in everyday chemical use are essential.
"One of the most surprising findings was how ciprofloxacin, widely used in Nordic countries, typically considered safe at low environmental concentrations, became much more harmful during a heatwave. This antibiotic, often prescribed for bacterial infections, disrupts the growth and health of aquatic species like phytoplankton when combined with extreme heat," Roth says.
The modeling study also revealed that dietary choices significantly influence chemical exposure. For example, vegetarians may have higher intake of certain pesticide residues found in crops, while omnivores are more likely to be exposed to pollutants like PCBs, which accumulate in animal products. This highlights how personal food choices, combined with climate change, can alter our exposure to environmental chemicals in unexpected ways.
While the research used simplified scenarios and specific test organisms, it represents a novel approach that opens the door to a deeper understanding of the combined effects of climate change and chemical pollution.
