Microplastics in agriculture – a potential novel mechanism for the delivery of human pathogens onto crops

Abstract

Mulching with plastic sheeting, the use of plastic carriers in seed coatings, and irrigation with wastewater or contaminated surface water have resulted in plastics, and microplastics, becoming ubiquitous in agricultural soils. Once in the environment, plastic surfaces quickly become colonised by microbial biofilm comprised of a diverse microbial community. This so-called ‘plastisphere’ community can also include human pathogens, particularly if the plastic has been exposed to faecal contamination (e.g., from wastewater or organic manures and livestock faeces). The plastisphere is hypothesised to facilitate the survival and dissemination of pathogens, and therefore plastics in agricultural systems could play a significant role in transferring human pathogens to crops, particularly as microplastics adhering to ready to eat crops are difficult to remove by washing. In this paper we critically discuss the pathways for human pathogens associated with microplastics to interact with crop leaves and roots, and the potential for the transfer, adherence, and uptake of human pathogens from the plastisphere to plants. Globally, the concentration of plastics in agricultural soils are increasing, therefore, quantifying the potential for the plastisphere to transfer human pathogens into the food chain needs to be treated as a priority.

Plastic Pollution in Agriculture as a Threat to Food Security, the Ecosystem, and the Environment: An Overview

“…Studies have reported that primary and secondary sources are the two main pathways through which plastic contaminants can enter agriculture. Both sources can be further defined as (1) primary sources include leakage or entry of plastic pollution from agricultural activities (such as mulching, irrigation, and fertigation) and ( 2) secondary sources include leakage or entry of plastic pollution from non-agricultural activities (such as plastic particles blowing in the air in urban areas and landfills) [152][153][154][155][156][157]. Climate variables such as high temperature, solar radiation, precipitation, and wind are among the factors responsible for physical weathering, aging, and quality deterioration of plastics in soils [158][159][160][161].…”

Towards a Sustainable Future: Advancing an Integrated Approach for the Recycling and Valorization of Agricultural Plastics

“…In addition to the negative effects of microplastics on soil health and productivity, there are also concerns regarding their consequences to ecosystems and the exposure of humans through food and water chains. In a recent study, researchers investigated the nature of microbial biofilms—the so-called “plastisphere”—that colonize microplastic surfaces [ 91 ]. They found that this community, when attached to plastic that has come into contact with feces (such as those from organic manures, wastewater, or animal waste), as is often the case for agricultural plastics, might be associated with human pathogens.…”

Crafting a Scientific Framework to Mitigate Microplastic Impact on Ecosystems

“…Due to their small size, MPs possess a significantly larger surface area, facilitating the adsorption of a wide range of pollutants on their often-hydrophobic surfaces. These tiny particles enter diverse environmental compartments, from rivers and soils to the atmosphere, and from the deepest depths of the oceans to the most remote areas of the polar regions [1][2][3][4][5][6].…”