ORIGINAL ABSTRACT

Over the last decade and worldwide, an enormous investment in research and data collection has been made in the hope of better understanding the possible ecological and toxicological impacts triggered by glyphosate (GLY). This broad-spectrum, systemic herbicide became the most heavily applied pesticide ever in the 2000s. It is sprayed in many different ways in both agricultural and non-agricultural settings, resulting in multiple routes of exposure to organisms up and down the tree of life. Yet, relatively little is known about the environmental fate of GLY-based herbicide (GBH) formulations, and even less on how GBH co-formulants alter the absorption, distribution, metabolism, excretion, and toxicity of GLY. The environmental fate of GLY depends on several abiotic and biotic factors. As a result of heavy annual GBH use over several decades, GLY residues are ubiquitous, and sometimes adversely affect non-target terrestrial and aquatic organisms. GLY has become a frequent contaminant in drinking water and food chains. Human exposures have been associated with numerous adverse health outcomes including carcinogenicity, metabolic syndrome, and reproductive and endocrine-system effects. Nonetheless, the existence and magnitude of GLY-induced effects on human health remain in dispute, especially in the case of heavily exposed applicators. A wide range of biochemical/physiological modes of action have been elucidated. Various GBH co-formulants have long been considered as inert ingredients relative to herbicidal activity but clearly contribute to GLY-induced hazards and risk gradients. In light of already-identified toxicological and ecosystem impacts, the intensive research focuses on GLY and GBHs should continue, coupled in the interim with commonsense, low-cost changes in use patterns and label requirements crafted to slow the spread of GLY-resistant weeds and reduce applicator and general-population exposures.