January 6, 2021 | Long-term exposure to formulated Roundup (glyphosate) results in significant harm to wildlife species that form the bottom of aquatic food chains, according to a study published in Microbiome by researchers at University of Birmingham, UK. The water flea Daphnia spp. often functions as a keystone species in lakes and ponds, and because of its ecological importance is frequently used as an indicator species in toxicity tests performed by pesticide regulators. Coauthor Luisa Orsini, PhD notes that most of this testing is flawed by limitations in its scope. “The problem is that much of the evidence is rooted in outdated toxicity tests which only look at the number of animals that die on exposure to extremely high concentrations of these chemicals,” Dr. Orsini said. “These tests also overlook the pathological effects arising from long-term exposure to low doses. What we’re proposing is that toxicity is measured by looking at what happens to the animal at a molecular and fitness level following long-term exposure, which encompasses the entire animal life cycle.” Dr. Orsini and her research team exposed populations of Daphnia magna to the maximum contaminant level (1 mg/L), set by the U.S. Environmental Protection Agency (EPA) for both the formulated product Roundup and technical grade glyphosate over the course of the animal’s life. The team then investigated a range of impacts and adverse changes that occurred as a result, including fitness burden, genotoxicity (damage to DNA), and alterations within the water flea’s gut microflora. A control population received no chemical exposure. Changes in fitness were seen for every trait except mortality. Roundup delayed average age of sexual/reproductive maturity, reduced size at maturity, decreased the total number of offspring produced, and increased developmental failure—as determined by the number of aborted eggs, and juveniles borne dead. [Suppa, Antoinio et al. Roundup causes embryonic development failure and alters metabolic pathways and gut microbiota functionality in non-target species. Microbiome. 8(170), 2020.]
