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Polyamide microplastics in wastewater as vectors of cationic pharmaceutical drugs.

Wagstaff, Antony; Lawton, Linda A.; Petrie, Bruce


Antony Wagstaff


Reported here is the first study to investigate the adsorption of pharmaceutical drugs to microplastics in wastewater. Wastewater is an environmental source of microplastics and pharmaceuticals, which is discharged as treated effluent or combined sewer overflows. In this study, adsorption of cationic pharmaceuticals, with a range of octanol-water distribution coefficients, to polyamide (Nylon 12) microplastics was investigated in real wastewater samples. Significant adsorption was observed for the more hydrophobic pharmaceuticals studied, propranolol, amitriptyline, and fluoxetine, with equilibrium reached within 24 h. Microplastic-wastewater distribution coefficients for these three pharmaceuticals were 191, 749 and 1020 L kg−1, respectively. Favourable wastewater conditions for adsorption of pharmaceuticals to polyamide were at pH>7, summer temperatures (20°C), and no stormwater dilution. Adsorption of the more hydrophilic pharmaceuticals atenolol, pseudoephedrine, metoprolol, and tramadol was ≤7% under all conditions and considered insignificant. Limited desorption (7–17%) of propranolol, amitriptyline, and fluoxetine was observed in river water over 24h. This suggests that microplastics may be able to transport adsorbed pharmaceuticals for considerable distances after discharge. In simulated gastric fluids their desorption increased to 24–27% and 40–58% in cold- and warm-blooded temperatures respectively. The findings demonstrate that wastewater microplastics could act as a vector of pharmaceutical drugs, from wastewater treatment plants to aquatic organisms. However, further research is needed to better appreciate the risks posed by pharmaceuticals adsorbed to microplastics in comparison to other organic particulates found in wastewater.


WAGSTAFF, A., LAWTON, L.A. and PETRIE, B. 2022. Polyamide microplastics in wastewater as vectors of cationic pharmaceutical drugs. Chemosphere [online], 288(Part 2), article 132578. Available from:

Journal Article Type Article
Acceptance Date Oct 13, 2021
Online Publication Date Oct 14, 2021
Publication Date Feb 28, 2022
Deposit Date Oct 18, 2021
Publicly Available Date Oct 15, 2022
Journal Chemosphere
Print ISSN 0045-6535
Electronic ISSN 1879-1298
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 288
Issue Part 2
Article Number 132578
Keywords Emerging contaminant; Adsorption; Desorption; Environmental chemistry; Water pollution; Microplastic
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