The rise of glyphosate and new opportunities for biosentinel early-warning studies

Glyphosate has become the most commonly used herbicide worldwide, with a reputation of being environmentally benign, non-toxic and safe to wildlife and humans. However, studies have indicated its toxicity has been underestimated, and that its persistence in the environment is greater than once thought. Its actions as a neurotoxin and endocrine disruptor indicate its potential to act in similar ways to persistent organic pollutants (POPs) such as the organochlorine (OC) chemicals dichlorodiphenyltrichloroethane (DDT) and dioxin. Exposure to glyphosate and glyphosate-based herbicides for both wildlife and people is likely to be chronic and at sub-lethal levels, with multiple and ongoing exposure events in both urban and agricultural landscapes. Despite this, little research attention has been given to the impact of glyphosate on wildlife populations, and existing studies appear in the agricultural, toxicology and water chemistry literature that may have limited visibility among wildlife biologists. There is a strong case for the recognition of glyphosate as an ‘emerging organic contaminant’ and significant potential exists for collaborative research between ecologists, toxicologists and chemists to quantify the impact of glyphosate on wildlife and to evaluate the role of biosentinel species in a preemptive move to mitigate downstream impacts on people. Success will depend on the development of new and novel non-destructive sampling and analysis methodologies as ex post facto identification of toxins at lethal levels has limited utility. Concentrating on the chemistry and toxicity of glyphosate, we have examined the published literature to evaluate the extent to which glyphosate based herbicides can cause toxic effects in wildlife and people and the implications of chronic exposure. We then explore the idea of using birds as bioindicators of glyphosate toxicity. We hope this may encourage future research into the uptake and impact of organophosphate chemicals in target species, particularly traditional indicator species such as birds