ORIGINAL ABSTRACT

Glyphosate, a widely used herbicide in both agricultural and non-agricultural practices, has become pervasive in the environment, leading to significant human and animal exposure. Despite growing evidence of its potential endocrine-disrupting and reproductive toxicity, European regulatory agencies continue to affirm its safety. This study examines the effects of glyphosate on male reproductive health by exposing adult zebrafish to dietary glyphosate at doses within European safety thresholds. After 21 days of exposure, testicular samples were analysed using a combined approach involving transcript analysis, targeted metabolomics and proteomics, epigenetics, as well as immunohistochemistry. At 0.5 mg/kg body weight(bw)/day (the acceptable daily intake, ADI), glyphosate impaired germ cell differentiation and triggered cell-specific changes in histone acetylation within the male germline. Higher exposure levels of 50 mg/kg bw/day (the no observed adverse effect level, NOAEL) induced metabolomic and proteomic disruptions linked to impaired steroidogenesis, DNA damage in germ cells, and alterations in testicular architecture, culminating in reduced reproductive capacity. Interestingly, minimal testicular effects observed at 5 mg/kg bw/day highlighted the non-monotonic dose-response relationship to glyphosate. These findings unveil critical molecular and cellular disruptions caused by glyphosate and emphasize its potential reproductive risks, even at doses considered "safe" by regulatory standards. This research contributes to ongoing discussions surrounding sustainable agricultural practices and public health policies, calling for a re-evaluation of glyphosate safety thresholds.