Agricultural frontiers are dynamic environments characterized by the conversion of native habitats to agriculture. Because they are currently concentrated in diverse tropical habitats, agricultural frontiers are areas where the largest number of species is exposed to hazardous land management practices, including pesticide use. Focusing on the Amazonian frontier, we show that producers have varying access to resources, knowledge, control and reward mechanisms to improve land management practices. With poor education and no technical support, pesticide use by smallholders sharply deviated from agronomical recommendations, tending to overutilization of hazardous compounds. By contrast, with higher levels of technical expertise and resources, and aiming at more restrictive markets, large-scale producers adhered more closely to technical recommendations and even voluntarily replaced more hazardous compounds. However, the ecological footprint increased significantly over time because of increased dosage or because formulations that are less toxic to humans may be more toxic to other biodiversity. Frontier regions appear to be unique in terms of the conflicts between production and conservation, and the necessary pesticide risk management and risk reduction can only be achieved through responsibility-sharing by diverse stakeholders, including governmental and intergovernmental organizations, NGOs, financial institutions, pesticide and agricultural industries, producers, academia and consumers.
The collapse of amphibian populations within pristine reserves worldwide suggests that diffuse, globally distributed factors such as pollution may be a cause of these declines. Nevertheless, cause-effect relationships between pollution and declines have proven difficult to establish at all scales, from local to global. We therefore aimed to quantitatively evaluate the weight of evidence for the role of pollution in global amphibian declines by first quantifying the published research on the effects of pollutants for all amphibian species in the world and then cross-referencing this information with species' biogeographic distribution, range area, and conservation status and with threats to species as summarized in the Global Amphibian Assessment. We found strong biogeographic and related taxonomic research biases, with a few, common, widely distributed generalist species from the northern hemisphere accounting for the majority of studies. Tropical regions, where more species and declines occur, were severely underrepresented in ecotoxicological research; therefore, current knowledge does not permit assessment of the significance of pollution in amphibian declines at a global scale or in regions where most declines occur. Moreover, if broader distributional ranges and occurrence at higher latitudes are correlated with broader environmental tolerances, current knowledge may considerably underestimate the sensitivity of the majority of amphibian species to pollutants. Finally, because species studied represent only a narrow subset of traits that mediate exposure and susceptibility to pollution, the current potential for extrapolation among species, guilds, ontogenetic phases, levels of complexity, habitat types, sites, and regions is weak. Ultimately, to mitigate these research biases and thus improve the basis for risk management, research policy must balance the spatial scale of the problem (global) and the distribution of knowledge (regional) so that biodiversity representation can be increased and regional bioindicators of environmental health can be developed.
Quaternary ammonium compounds (QACs) are cationic surfactants that are widely used as disinfectants. In the present study, we tested two important representatives, namely, benzalkonium chloride (BAC) and dimethyldioctadecyl-ammonium bromide (DDAB) in four genotoxicity tests, namely, in the Salmonella/microsome assay with strains TA 98, TA 100 and TA 102, in the single-cell gel electrophoresis (SCGE) assay with primary rat hepatocytes and in micronucleus (MN) assays with peripheral human lymphocytes and with root tip cells of Vicia faba. In the bacterial experiments, consistently negative results were obtained in the dose range between 0.001 and 110 microg per plate in the presence and absence of metabolic activation while significant induction of DNA migration was detected in the liver cells. With BAC, a moderate but significant effect was found with an exposure concentration of 1.0 mg/l while DDAB caused damage at lower doses (0.3 mg/l). The effects were not altered when the nuclei were treated with formamidopyridine glycosylase, indicating that they are not due to formation of oxidized purines. The MN assays with blood cells were carried out under identical conditions to the SCGE experiments and a significant increase was seen at the highest dose levels (BAC: 1.0 and 3.0 mg/l; DDAB: 1 mg/l). Both compounds also caused significant induction of MN as well as inhibition of cell division in plant cells, the lowest effective levels were 1.0 and 10 mg/l for DDAB and BAC, respectively. Our findings show that both chemicals induce moderate but significant genotoxic effects in eukaryotic cells at concentrations which are found in wastewaters and indicate that their release into the environment may cause genetic damage in exposed organisms. Furthermore, the direct contact of humans to QAC-containing detergents and pharmaceuticals that contain substantially higher concentrations than those which were required to cause effects in eukaryotic cells in the present study should be studied further in regard to potential DNA-damaging effects in man.
Global interest in biofuels is driving a continuous expansion of agroindustrial production in tropical countries, bringing a substantial share of the world's biodiversity into contact with hundreds of potentially hazardous pesticides. We reviewed the hazards imposed by all 784 pesticides currently registered for use on biofuel crops in Brazil. We detected compounds that have been suspended by international conventions, as well as over 80 compounds included in lists of priority concern for exhibiting environmental persistence and/or having the potential to elicit neurotoxic, reprotoxic, carcinogenic, or endocrine‐disrupting effects in humans and wildlife. These chemicals will be used at increased rates, or for the first time, across large expanses of agroin‐dustrially converted pastures and native (ie pristine) habitat in the cerrado (tropical savanna) and Amazonian rainforest biomes. If human and environmental health are to be balanced with productivity to achieve a sustainable agriculture, bolder initiatives on pesticide restriction and control must be implemented in tropical countries.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.