Investigating the Influence of Pesticide Exposure on the Human Gut Microbiome

Abstract

Background: Pesticides are widely used in the agricultural industry and can cause unintentional harm to non-target organisms, including humans. The public health effects of exposure to pesticides have been widely examined, however impacts on the human gut microbiome have been rarely investigated. Dysbiosis of the gut microbiota has been linked with many disease states and could have critical associations with the adverse health effects observed following pesticide exposure. Experimental animal studies have shown significant alterations of the microbial structure following both short-term and long-term exposure to pesticides but further studies are required to clarify the microbial effects in humans.

Objectives: Our primary aim is to determine whether personal exposure measurements reflecting short- and medium-term pesticide exposure are linked with structural alterations of the human gut microbiome. Additionally, we aim to investigate the impacts of long-term pesticide exposure on microbial structure by comparing the gut microbiomes of organic and non-organic farmers.

Methods: Short-term pesticide exposure will be defined and quantified using measured urine concentrations of five specific pesticide metabolites. Proxies of medium-term pesticide exposure include analysis of compounds adsorbed by silicone wristbands worn by participants and analysis of participant hair samples. Non-organic farmers will represent individuals with long-term pesticide exposure. To explore the impacts of short-, medium- and long-term pesticide exposures on the gut microbial structure, we will inspect different characteristics of the microbiome. Alpha and beta diversity will be explored in relation to pesticide exposures and we will also determine whether there are specific differentially abundant bacterial species in relation to pesticide exposure using differential abundance analysis.

Expectations and applicability of results: As a result of pesticide exposure, we expect to find significant alterations in the gut microbial structure. By elucidating possible pesticide-induced gut microbial alterations, we hope to determine whether the gut microbiome should be a target of interest to investigate in future safety assessments of pesticides. By investigating the effects of different exposure durations, we will be able to identify individuals at greatest risk, which may drive the development of additional exposure prevention strategies.