Microplastics as carriers of antibiotic resistance genes in agricultural soils: A call for research

Plastic contamination has become a major environmental concern and impacts human health, and yet this is still a topic that remains largely understudied. Effects of macro- and microplastics on soil physical, chemical, and biological properties, including soil biota, are considered adverse for soils. Due to their small size and porous surface, microplastics can also be a new environmental concern because of their ability to act as carriers of contaminants or diseases. This issue has become particularly relevant in agricultural soils because antibiotics can be present in manure or other kinds of amendments applied to farmlands or adsorbed on agricultural plastics that can be incorporated into soil. Furthermore, plastic debris can serve as a pollutant and carrier of pathogens or antibiotic resistance genes because plastics can favor modifications of bacterial cell membranes, thereby posing increased risks for the environment and humans. Although a vast amount of research has been done on the role of microplastics as tetracycline or oxytetracycline carriers, no studies have considered highly mobile antibiotics such as clarithromycin and combined exposure with microplastics in soil. In addition, more research should focus on the potential impacts of global change on degradation of plastics, especially biodegradable plastics, and plastic impact on the release of contaminants.