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Obstacle 9 - Our limited knowledge on the impact of mixtures of multiple pollutants

Updated December 2021

Massive pollution by thousands of pollutants is one of the main drivers of biosphere’s disintegration (Landrigan et al. 2017; Wilkinson et al. 2017; Geissen et al. 2018; Wiesinger et al. 2021).


Most existing legislation on pollution control (BAT- Best Available Technology standards and EQOs - Environmental Quality Objectives) is restricted to the control of single pollutants. This is due to the limited knowledge available on the accumulative and synergistic effects of mixtures of multiple pollutants, mixtures found in most situations today (Russo 2018; Altenburger et al. 2019; Figure 1). Thus, the lack of tools to actually control pollution becomes a conspicuous obstacle to sustainability.

The toxicity tests and bioassays are potential alternatives to overcome this limitation. They evaluate the toxicity of a sample (e.g., a water sample) on some specific organisms. The test does not identify the pollutants present in the sample but the combined toxicity of the mixture of pollutants in it. Unfortunately, toxicity tests are available for a very limited number of organisms which by far are not representative of the numerous different communities in biosphere. Bioassays also make use of single organisms and run during limited periods of time. The use of short-term tests on few organisms to evaluate the long-term effect of mixtures of pollutants on real biological communities results into underestimations of the impacts (Moore et al. 2019).


Another potential alternative to overcome the problem is the use of holistic analyses combining EQOs, advanced chemical screening of potential pollutants, biomarkers, bioassays and the assessment of the ecological status of the whole biological community (Martinez-Haro et al. 2015; Altenburger et al. 2019). The approach is correct from a scientific point of view, but it is too time-consuming as a day-to-day administrative tool to handle discharge permits, monitor pollution and assure sustainability (Russo, 2018).

Multiple pollutants.JPG

Figure 1. Pollutants in the environment - past and present situations


Altenburger R, E Back, R Brugess et al. (2019) Future water monitoring: improving the balance between exposure and toxicity assessments of real-world pollutant mixtures. Environ. Sci. Eur. 31:12.  

Geissen V., C. Ritsema, X. Yang, and V. Silva (2018). 60 years of pesticide application – pitfalls and prospects. In: Proc. Global Symposium Soil Pollution, FAO - Rome, p.79.

Landrigan P, R Fuller, N Acosta et al. (2017) - The Lancet Commission on pollution and health. The Lancet 391(10119):462-512.

Martinez-Haro M, R Beiras, J Bellas et al. (2015) A review on the ecological quality status assessment in aquatic systems using community-based indicators and ecotoxicological tools: what might be the added value of their combination? Ecolog. Indicators 48:8-16.

Moore D, D Farrar, S Altman and T Bridges (2019) Comparison of acute and chronic toxicity laboratory bioassay endpoints with benthic community responses in field-exposed contaminated sediments. Envio. Toxic. Chem. 38(8):1784-1802.

Russo G (2018) Can BC’s 40-year-old Water Quality Objectives policy solve today’s challenges for managing cumulative effects? MSc Thesis, Univ Victoria-Canada, 160 pp.

Wiesinger H, Z Wang and S Hellweg (2021) Deep dive into plastic monomers, additives and processing aids. Enviro. Sci. Technol. acs.est.1c00976.

Wilkinson J., P Hooda, J Barker, S Barton and J Swinden (2017) Occurrence, fate and transformation of emerging contaminants in water: An overarching review of the field. Environ. Pollut. 231(1):954-970.

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