(Beyond Pesticides, May 8, 2025) A study, published in Environmental Pollutants and Bioavailability, assesses the impacts on Nile tilapia (Oreochromis niloticus) with subacute and chronic exposure to thiamethoxam, a neonicotinoid insecticide, and finds genotoxicity, oxidative stress, and changes in tissue structure, among other threats to organ function and overall fish health. “The study focused on biochemical markers, genetic damage, pesticide residue levels in fish flesh, and histopathological changes in fish exposed to different concentrations of thiamethoxam,” the authors state. The threats do not end there; human health is also at risk from the consumption of these contaminated fish. “Unfortunately, neonicotinoids, rapidly washed into surface water from agricultural areas, pose a significant threat to environmental water quality and can harm non-target species, particularly aquatic organisms,” the researchers state. The accumulation of these chemicals leads to “ultimately harming both aquatic ecosystems and human health,” they say. In particular, the study highlights that prolonged exposure to high doses of thiamethoxam can cause “significant negative effects on fish health,” the authors note. They continue: “This exposure led to increased levels of urea and ALT [alanine aminotransferase] in the blood, indicating potential damage to the kidneys and liver. Additionally, thiamethoxam caused oxidative stress, as evidenced […]

(Beyond Pesticides, May 6, 2025) A study in Ecology Letters finds “severe degradation of ecosystem functioning in the form of loss of organic matter consumption and dramatic shifts in primary productivity,” the researchers state, after performing an experiment with “36 naturally established freshwater ecosystems exposed to increasing field-realistic concentrations of the neonicotinoid thiacloprid.” Aquatic communities contribute to overall biodiversity and are crucial in maintaining healthy ecosystems; without them, the entire food web and vital ecosystem services, such as nutrient cycling, water filtration, and climate regulation, are threatened. As the authors reference, there is a current unprecedented decline in biodiversity that can be attributed to anthropogenic impacts. A multitude of studies connect pesticides, and more specifically neonicotinoid insecticides, to impacts on aquatic ecosystems. (See studies here and here.) “Since the community of organisms locally present is responsible for the functioning of the local ecosystems,” the researchers begin, “this begs the question: do neonicotinoid-induced shifts in community composition result in a degradation of ecosystem functioning?” Previous research finds that neonicotinoids can “impede several freshwater ecosystem processes such as organic matter (‘OM’) decomposition, primary production or biomass transfer to neighbouring ecosystems,” the authors say. (See studies here, here, and here.) They continue: “However, […]

(Beyond Pesticides, April 29, 2025) A study in Environment International finds pesticide-induced alterations in the gut microbiota of a farmland raptor species. In collecting blood and cloacal samples from Montagu’s harrier (Circus pygargus) nestlings, the authors “shed light on an overlooked collateral effect of pesticides, i.e., a general modification of gut bacterial assemblages,” which can lead to an imbalance of microorganisms (dysbiosis) and the promotion of potential pathogens, as well as negatively impact the health of birds of prey. “Additionally, our findings support the ‘One Health‘ framework, stressing the interconnectedness of wildlife, ecosystem, and human health, particularly in pesticide-affected agricultural areas,” the researchers share. “The gut microbiota is crucial for host health and can be impacted by various environmental disruptions, yet the effects of multiple pesticide exposures on farmland organisms’ microbiomes remain largely unexplored,” the authors state. In the study, they “assessed microbiota changes in a wild apex predator exposed to multiple pesticides in agricultural landscapes,” which “provides evidence of pesticide impacts on wildlife gut microbiota, highlighting links between pesticide exposure and changes in microbiota composition,” the researchers note. The Montagu’s harrier, as an apex predator, serves as a ‘bio-sentinel’ or bioindicator species for assessing ecosystem health. “As top-level predators […]

(Beyond Pesticides, March 20, 2025) An article, published by the National Audubon Society, titled “A Sweeping New Report Shows U.S. Birds Declining Sharply Across a Range of Habitats” reviews the latest State of the Birds 2025 report and finds concerning news for bird species across the country. As the article says: “Whether they hop around the prairie, dabble in wetlands, flit through forests, or forage along the shore, birds are suffering rapid population declines across the United States… If these habitats are struggling to support bird species, it’s a sign that they’re not healthy for other wildlife, or even humans—but working to restore them will have benefits across ecosystems.” The 2025 edition of the State of the Birds report, showcasing a status assessment of the health of the nation’s bird populations, was cultivated by scientists from bird conservation groups through the U.S. Committee of the North American Bird Conservation Initiative (NABCI). The report notes, “Despite ample evidence that conservation can work, the status quo approach to conservation is not turning bird populations around.” As NABCI shares, the report contains “[s]obering evidence that America’s birds continue to decline across the board.” They continue, saying: “Birds are telling us that the habitats […]

(Beyond Pesticides, March 18, 2025) The November 2024 press release by the U.S. Environmental Protection Agency (EPA) for its Rodenticide Strategy includes the final biological evaluation (BE) of 11 rodenticides. Prior to the finalization of the BE, Beyond Pesticides commented to EPA’s Office of Pesticide Programs in early 2024, disagreeing with the categorical no effect (NE) determinations for all freshwater and marine fish, aquatic mammals, aquatic amphibians, aquatic reptiles, and aquatic invertebrates. (See related Daily News and Action of the Week.) The latest scientific literature highlights the impacts of rodenticides on nontarget organisms, including aquatic organisms that the agency failed to evaluate due to harm that was, as EPA says, “not reasonably certain to occur.” Many rodenticides, intended to target rats, mice, squirrels, nutria, and more, are anticoagulants and stop normal blood clotting. Active ingredients in these pesticides can include bromadiolone, chlorophacinone, difethialone, brodifacoum, and warfarin. Anticoagulant rodenticides (ARs), contrary to the agency’s assertions, can be transported to aquatic ecosystems, including both freshwater and marine environments. As mentioned in Beyond Pesticides’ comments, ARs have been detected in raw and treated wastewater, sewage sludge, estuarine sediments, suspended particulate matter, and liver tissues of sampled fish, demonstrating that the aquatic environment experiences […]

(Beyond Pesticides, December 10, 2024) Scientists from the Engineering Research Center of Protection and Utilization of Plant Resources at Shenyang Agricultural University in China reveal adverse effects of imidacloprid on soil communities in a study published in Pesticide Biochemistry and Physiology. The researchers highlight risks to nematodes from imidacloprid exposure in maize soil, as well as potential resistance mechanisms that impact not only nematode populations but also overall soil health. Maize, or corn, a productive crop grown worldwide, is a source of food and biofuel. In assessing the soil and species in maize fields after exposure to imidacloprid at various concentrations, the study researchers assess the impact of neonicotinoid insecticides on nontarget organisms and the health of soil communities. The assessment includes an evaluation of nematodes’ survival, growth, reproduction, and chemotaxis/locomotion behavior. With a statistical analysis of lipid and lipofuscin accumulation, acetylcholinesterase (an enzyme necessary for neurotransmission) activity, and gene expression levels, the study results show that imidacloprid induces: significantly reduced abundance and diversity of nematode species. negative effects on body length, reproduction, locomotion, lipid accumulation, lipofuscin accumulation, and acetylcholinesterase activity in Caenorhabditis elegans ( elegans). the upregulation of gpa-1, cyp-35a2, fat-2, fat-6, hsp-16.41, and hsp-16.2, along with the downregulation […]

(Beyond Pesticides, October 25, 2024) To better understand synergistic interactions between multiple stressors, researchers from the Helmholtz Centre for Environmental Research in Leipzig, Germany, analyze exposure to the pyrethroid insecticide esfenvalerate with two nonchemical environmental factors: elevated temperature and food limitation. In their recent publication in Environmental Pollution, the authors find the greatest synergistic effects when Daphnia magna (D. magna) are subjected to esfenvalerate under conditions experienced with climate change including lower food availability and increased temperature. D. magna, also known as daphnids or water fleas, are small planktonic crustaceans that represent an essential part of the food web in lakes and ponds. Impacts on populations of daphnids can lead to effects throughout multiple trophic levels that impact overall biodiversity. As the researchers state, “Global biodiversity is declining at an unprecedented rate in response to multiple environmental stressors… A key challenge is understanding synergistic interactions between multiple stressors and predicting their combined effects.” To study this, a Stress Addition Model (SAM), which predicts the cumulative effects of interacting stressors, was utilized and compared to laboratory data using 24-hour-old neonates of D. magna. The organisms were subjected to various conditions, singularly and in combination, including increased temperature, lower quantities of food, […]

(Beyond Pesticides, October 22, 2024) A recent study, published through the American Chemical Society, analyzes pesticide contamination in riparian soil and plants as a result of flooding from streams in Germany. The authors hypothesize, and then prove, that frequently flooded sites have higher levels of pesticides present due to the pesticides in surface waters contaminating the soil. Results show that the plant vegetation in the contaminated soil then takes up the pesticides, which bioaccumulate and lead to higher contamination that can further cascade throughout the ecosystem and affect terrestrial food webs. “[O]ur study provides evidence from the field that nontarget plant species typical for riparian stream sites receive considerable pesticide exposure via flooding events,” the authors share. This exposure, and subsequent bioaccumulation in plants, threatens the food web, as many riparian plants are a vital food source for insects. According to the authors, flooding events, and their impact on pesticide contamination within soil and plants, are rarely investigated. This study, “measur[ing] 98 pesticides and metabolites in plants and root-zone soils sampled at five streams situated in an area in Southwest Germany characterized by intensive agricultural land use,” highlights the differences in contamination between frequently flooded and rarely flooded areas and […]

(Beyond Pesticides, May 22, 2024) A study in the journal of Environmental Science and Technology Letters, funded by the National Oceanic and Atmospheric Administration, is the first to find halogenated organic compounds (HOCs) in deep ocean sediment and biota off the coast of California. The test area, known as the Southern California Bight (SCB), is home to historic offshore DDT waste dumping, with part of the SCB designated as a U.S. Environmental Protection Agency (EPA) Superfund site. 49 HOCs were detected in the sediment and biota, many of which are DDT-related and not previously screened for. The presence of these “unmonitored compounds can significantly contribute to the contaminant body burden across a range of marine taxa,” the study states, which leads to impacts on critical food webs and biodiversity. While this study is the first to specifically analyze previously overlooked DDT+ compounds, the results are nothing new. There is a body of science around the bioaccumulation and biomagnification of harmful pollutants that continue to lead to a decline in biodiversity, negative impacts on water and soil, and detrimental human health effects.       To assess the bioavailability of DDT+ and HOCs in the deep ocean food web, this study focused on […]