# Immunomodulatory effects of the herbicide glyphosate following occupational exposure

## TL;DR

This study finds that glyphosate exposure alters immune responses in vineyard workers, favoring Th2 over Th1 activity.

## Contribution

The study provides new evidence linking glyphosate exposure to specific immune system changes in humans.

## Key findings

- Glyphosate exposure increased IL-4 and IL-5 cytokine levels while decreasing IL-8.
- A reduced Th1/Th2 cell ratio was observed, aligning with elevated Th2 cytokines.
- Exposure was associated with decreased miR-500a levels and possible microbiota dysbiosis.

## Abstract

Glyphosate, a widely used herbicide, has raised concerns regarding its impact on human health and the environment due to its widespread and excessive use. Adverse effects on the immune system have been reported. In this study, 26 vineyard workers in Veneto vineyards were examined before and after glyphosate applications to investigate possible immune parameter changes. Glyphosate exposure led to alterations in plasma cytokine levels, including marked increases in IL-4 and IL-5, a modest rise in IFN-γ, and a decrease in IL-8. No changes in plasma IL-12/23p40, IL17 and IL-33 were found. The IFN-γ/IL-4 ratio decreased, accompanied by changes in T cell subpopulations. Notably, a decrease in the T helper 1/T helper 2 cell ratio, attributed to reduced Th1 cells and increased Th2 cells, was observed, aligning with the elevated Th2 cytokines. A reduction in plasmatic extracellular vesicular miR-500a levels following glyphosate exposure was found, potentially contributing to the immunological findings. A slight decrease in plasma lipopolysaccharide levels in exposed workers excluded systemic inflammation from increased intestinal permeability but hinted at a possible association with glyphosate-induced microbiota dysbiosis. Since the shikimate pathway, targeted by glyphosate, is also present in Gram-negative bacteria. Overall, these findings suggest that glyphosate can affect the immune system, favoring Th2 responses. While more research is needed to establish causality with the association of glyphosate exposure with the development of allergic reactions in susceptible individuals, our results shed light on potential underlying mechanisms.

The online version contains supplementary material available at 10.1007/s00204-025-04156-3.