Microplastics as Vectors of Pharmaceuticals in Ecosystem: A Concern

Close-up on micro plastic particles. The concept for water pollution and global warming. Macro shot on a bunch of microplastics that cannot be recycled. | Image Credit: © SIV Stock Studio - stock.adobe.com

The global ecosystem will always be a primary concern to humans, but with a new industrial revolution currently at its boom, the bio/pharmaceutical industry must be mindful of that revolution’s repercussions. Microplastics, a byproduct of plastics commonly used in packaging, could be vectors for organic contaminants.

When it comes to pharma, these organic contaminants may be considered drugs with intended, efficacious effects as well as unintended and toxic ones. Depending upon levels of drugs that remain in used and/or discarded packages, these organic contaminants can enter the ecosystem and have damaging effects. So, there is a need to be sensitized to this topic, and for the industry to do its part to remedy it.

History and current state of affairs

The advent of plastics has revolutionized the pharmaceutical packaging industry. Whether it is solutions, suspensions, powders, granules, tablets, and capsules in bottles, or ointments, creams, gels, and pastes in tubes, or injectable solutions in infusion bags and syringes, plastics are ubiquitous. Plastics provide advantages in packaging not only to manufacturers but also end-users in terms of ease of storage and handling.

However, evolution comes at a cost. The major menace in the use of plastics is proper disposal. Lack of awareness for adequate segregation of waste from home and hospital setups, and limited facilities for proper treatment of plastic wastes, have added to this bioburden. The degradation or fragmentation of plastics results in macroplastics (>2.5 cm), mesoplastics (0.5–2.0 cm), microplastics (0.5 cm–1.0 µm), and nanoplastics (<1.0 µm) (1).

The real issue is not with the fragments themselves but their capacity to be vectors for transport of hydrophobic organic contaminants (2). These plastics could be of varying chemistries—namely, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate, polyamide, polyacrylonitrile, etc. (3). In the context of pharmaceuticals, these organic contaminants are drugs and chemicals that are absorbed or adsorbed to these plastics depending upon their physicochemical properties (4).

Sources and symptoms

Various molecular properties such as dissociation or ionization constant, or partition or distribution coefficient, govern the solubility of a compound and its differential migration into hydrophilic or lipophilic matrices. Once disposed of after their use, these packages—and the microplastic they contain—enter our ecosystem through wastewater treatment plants or degradation of plastic debris (5).

Wastewater treatment plants could be a further source of transmission of microplastics to agriculture fertilizers. This poses a huge bioburden on the ecosystem in terms of bioaccumulation and biomagnification of organic contaminants; again, for purposes of this discussion, these contaminants should be considered drugs. The aging of microplastics further enhances the adsorption of organic compounds (6).

Sources for human exposure to these organic contaminants could be seafood, terrestrial food, drinking water, inhalation, or salt from sea water, meaning that unintentionally, these drugs may ingress the human body through the food chain. Associated health hazards may be evident in the form of skin irritation, respiratory problems, cardiovascular diseases, digestive problems, reproductive issues, and other symptoms (7).

Future considerations

The bigger threat may be in terms of developing antibiotic resistance, which could be driven by genetic modifications in the aquatic ecosystem (8). According to a World Health Organization report published in 2019, fresh water may contain 1 to 1000 particles per liter, while drinking water may contain 0 to 10,000 particles per liter (9).

While efforts are ongoing to understand and control this growing problem, the impact to the wildlife and aquatic ecosystem of ingested, micropollutant-loaded microplastics remains a concern.

References

1. Blettler, M. C. M.; Ulla, M. A.; Rabuffetti, A. P.; Garello, N. Plastic Pollution in Freshwater Ecosystems: Macro-, Meso-, and Microplastic Debris in a Floodplain Lake. Environ. Monit. Assess. 2017, 189, 581. DOI: 10.1007/s10661-017-6305-8
2. Santos, L. H. M. L. M.; Rodríguez-Mozaz, S.; Barceló, D. Microplastics as Vectors of Pharmaceuticals in Aquatic Organisms—An Overview of Their Environmental Implications. Case Stud. Chem. Environ. Eng. 2021, 3, 100079. DOI: 10.1016/j.cscee.2021.100079
3. European Commission. A European Strategy for Plastics in a Circular Economy; European Commission, 2018.
4. Atugoda, T.; Vithanage, M.; Wijesekara, H.; et al. Interactions Between Microplastics, Pharmaceuticals and Personal Care Products: Implications for Vector Transport. Environ. Int. 2021, 149, 106367. DOI: 10.1016/j.envint.2020.106367
5. Zhou, R.; Lu, G.; Yan, Z.; et al. A Review of the Influences of Microplastics on Toxicity and Transgenerational Effects of Pharmaceutical and Personal Care Products in Aquatic Environment. Sci. Total Environ. 2020, 732, 139222. DOI: 10.1016/j.scitotenv.2020.139222
6. Moura, D. S.; Pestana, C.,J.; Moffat, C. F.; et al. Aging Microplastics Enhances the Adsorption of Pharmaceuticals in Freshwater. Sci. Total Environ. 2024, 912, 169467. DOI: 10.1016/j.scitotenv.2023.169467
7. Klavins, M.; Klavins, L.; Stabnikova, O.; et al. Interaction between Microplastics and Pharmaceuticals Depending on the Composition of Aquatic Environment. Microplastics 2022, 1 (3) 520–535. DOI: 10.3390/microplastics1030037
8. Laganà, P.; Caruso, G.; Corsi, I.; et al. Do Plastics Serve as a Possible Vector for the Spread of Antibiotic Resistance? First Insights from Bacteria Associated to a Polystyrene Piece from King George Island (Antarctica). Int. J. Hyg. Environ. Health 2019, 222 (1) 89–100. DOI: 10.1016/j.ijheh.2018.08.009
9. World Health Organization. Microplastics in Drinking-Water; World Health Organization, August 2019.

About the author

Piyush Gupta is an expert pharmaceutical consultant based in Bengaluru, India.