Modelling local nanobiomaterial release and concentration hotspots in the environment

Bernd Nowack,Marina Hauser

doi:10.1016/j.envpol.2021.117399

Abstract

Nanobiomaterials (NBMs) are a special category of nanomaterials used in medicine. As applications of NBMs are very similar to pharmaceuticals, their environmental release patterns are likely similar as well. Different pharmaceuticals were detected in surface waters all over the world. Consequently, there exists a need to identify possible NBM exposure routes into the environment. As the application of many NBMs is only carried out at specific locations (hospitals), average predicted environmental concentrations (PECs) may not accurately represent their release to the environment. We estimated the local release of poly(lactic-co-glycolic acid) (PLGA), which is investigated for their use in drug delivery, to Swiss surface waters by using population data as well as type, size and location of hospitals as proxies. The total mean consumption of PGLA in Switzerland using an explorative full-market penetration scenario was calculated to be 770 kg/year. 105 hospitals were considered, which were connected to wastewater treatment plants and the receiving water body using graphic information system (GIS) modelling. The water body dataset contained 20,167 river segments and 210 lake polygons. Using the discharge of the river, we were able to calculate the PECs in different river segments. While we calculated high PLGA releases of 2.24 and 2.03 kg/year in large cities such as Geneva or Zurich, the resulting local PECs of 220 and 660 pg/l, respectively, were low due to the high river discharge (330 and 97 m3/s). High PLGA concentrations (up to 7,900 pg/l) on the other hand were calculated around smaller cities with local hospitals but also smaller receiving rivers (between 0.7 and 1.9 m3/s). Therefore, we conclude that population density does not accurately predict local concentration hotspots of NBMs, such as PLGA, that are administered in a hospital context. In addition, even at the locations with the highest predicted PLGA concentrations, the expected risk is low.

Highlights

Nanomaterials are defined as materials with external dimensions in the nanoscale or with an internal surface structure at the nanoscale between 1 and 100 nm (ISO, 2015)
We estimated the local release of poly(lactic-co-glycolic acid) (PLGA), which is investigated for their use in drug delivery, to Swiss surface waters by using population data as well as type, size and location of hospitals as proxies
While Kawecki and Nowack (2020) calculated emissions to water and soil, we only focused on surface water as emissions to soil are not expected to occur for PLGA

Summary

Introduction

Nanomaterials are defined as materials with external dimensions in the nanoscale or with an internal surface structure at the nanoscale between 1 and 100 nm (ISO, 2015). Engineered nanomaterials (ENMs) are deliberately designed and prepared materials with nanoscale di mensions (Gubala et al, 2018). Nanomaterials are used in the medical field for the use in pharmaceutics and biomedical engi neering (Küster and Adler, 2014). Nanomaterials designed to interact with the biological system for a medical purpose are termed nano biomaterials (NBMs) (Merriam-Webster, 2020). A handful of studies so far have evaluated the flows of NBMs to the environment. The flows of nano-silver (nano-Ag) used in wound dressing were estimated by Arvidsson et al (2011).

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