Effects of glyphosate (GLY) and GLY-based herbicides (GBH) on animals: A meta-analytical approach

Glyphosate (GLY)-based herbicides (GBHs) are the most commonly applied pesticide worldwide, and non-target organisms (e.g., animals) are now regularly exposed to GLY and GBHs due to their accumulation in many environments. Although GLY/GBH was previously considered to be non-toxic, growing evidence indicates that GLY/GBH negatively affects some animal taxa. However, there has been no systematic analysis quantifying its effects in animals. Therefore, we used a meta-analytical approach to review previously published literature to address four questions: Do the effects of GLY/GBH vary due to (1) taxon (invertebrate vs. vertebrate), (2) habitat (aquatic vs. terrestrial), (3) type of exposure (ingestion vs. absorption through water in the environment), or (4) measured variable (behavior vs. physiology vs. survival). Our approach also allowed us to determine whether effects were caused by the GLY itself, or by other surfactants found in GBHs. The Scopus scientific database was used to analyze 833 observations across six types of dependent variables (survival; reproduction; growth, development, or morphology; physiology; behavior; and population level) from 85 articles. Hedge’s g values were calculated to determine the effect size for each observation, and statistical analysis was performed using the JASP freeware program. Our meta-analysis will be the first to examine the effects of GLY/GBH on ecosystems by comprehensively quantifying its impacts on animals