Investigating the environmental fate of active pharmaceutical compounds in a coastal lagoon using a multimedia level III fugacity model

The use of active pharmaceutical ingredients (APIs) has enhanced life quality and longevity but poses significant environmental risks to ecosystems and human health. Evidence-based risk assessments are essential for addressing these issues, requiring detailed data on API presence, behavior, and effects in the environment. In particular, predictive exposure models offer a cost-effective tool to support such investigations. This study focuses on the application of a multimedia level III fugacity model to estimate the predicted environmental concentrations (PECs) and to simulate transport, distribution, and persistence of nine APIs in the Venice Lagoon (Italy), a transitional environment subjected to multiple anthropogenic stressors. Concentrations of the studied APIs in water were estimated within one order of magnitude of measured data, while the model underestimated the concentration of azithromycin and 17-β-estradiol in the sediments due to water half-life overestimation and lack of information about unmonitored emission sources. In detail, the highest levels of APIs in the water were estimated for amoxicillin and clarithromycin, while sediments showed a significant presence of azithromycin and ciprofloxacin. Model results also showed the possibility for sediments to act as sink for azithromycin, ciprofloxacin, erythromycin, estrone, and 17-β-estradiol. For all target APIs, degradation in the water column and adjective outflow were the most important elimination processes, while degradation in the sediments was significant only for erythromycin, ciprofloxacin, and clarithromycin. Monte-Carlo uncertainty and sensitivity analysis showed that degradation in water, affinity to organic matter, and sediment dynamics were the parameters with the strongest influence on model’s results. Overall, this work provided valuable information on the environmental fate and behavior of the investigated APIs in a complex transitional waterbody such as the Venice Lagoon and can be useful to support future environmental risk assessments as well as studies to evaluate the effects of emission control measures (e.g., restriction of use, substitution, or implementation of new technologies for wastewater treatment) on APIs environmental exposure.