LB 16-176 - Modelling the environmental risk of antibiotics in the global river system

Background/Question/Methods:

Antibiotics are not fully metabolized in human bodies, being excreted to the waste system and later reaching our rivers, posing a risk of severe impacts to the health of aquatic ecosystems, including the bloom of drug-resistant bacteria. Still, there is a lack of observational data in the field since these substances are not typically included in routine monitoring programs, especially in developing regions. With this in mind, we developed a model, called HydroFATE, to estimate the emission of antibiotics and their subsequent transport in river networks at a global scale and a high spatial resolution, providing estimates of concentrations of these substances in every river in the world. A key component of HydroFATE is the integration of a novel global database of 58,502 wastewater treatment plants, which includes sufficient information to geo-locate point sources and estimate the emission of the contaminant discharges into river networks. These predicted concentrations are then used in an environmental risk assessment of the impact of antibiotics in the global river system, based on thresholds protective of antimicrobial resistance and ecological species.

Results/Conclusions:

At low-flow conditions, we estimate a total of 6.9 million km of rivers presenting possible risk of negative environmental impacts of antibiotics. Some of the regions most affected due to population density, high antibiotic consumption, lack of adequate treatment, and low levels of river discharge are Southeast Asia and Africa. On the other hand, locations in high income regions such as Europe and North America also present high risk for some substances. Given the high spatial resolution, these results can be used to identify specific areas in river networks where high risks (or ‘hot-spots’) are expected. Our findings can support decision-making in policy and management efforts to mitigate negative impacts and aid in the prioritization of monitoring or conservation strategies to safeguard aquatic ecosystem health.