Nanoparticle silver coexposure reduces the accumulation of weathered persistent pesticides by earthworms

Abstract

Although the use of engineered nanomaterials continues to increase, how these materials interact with coexisting contaminants in the environment is largely unknown. The effect of silver (Ag) in bulk, ionic, and nanoparticle (NP; bare and polyvinyl pyrrolidone-coated) forms at 3 concentrations (0 mg/kg, 500 mg/kg, 1000 mg/kg, 2000 mg/kg; ion at 69 mg/kg, 138 mg/kg, 276 mg/kg) on the accumulation of field-weathered chlordane and dichlorodiphenyldichloroethylene + metabolites (DDX) by Eisenia fetida (earthworm) was investigated. Earthworm biomass and survival were unaffected by treatment. At the 500 mg/kg and 1000 mg/kg exposure levels, NP-exposed earthworms contained significantly greater Ag (194-245%) than did the bulk exposed organisms; NP size or coating had no impact on element content. Generally, exposure to Ag of any type or at any concentration significantly reduced pesticide accumulation, although reductions for DDX (35.1%; 8.9-47.0%) were more modest than those for chlordane (79.0%; 17.4-92.9%). For DDX, the reduction in pesticide accumulation was not significantly affected by Ag type or concentration. For chlordane, the 3 NP exposures suppressed chlordane accumulation significantly more than did bulk exposure; earthworms exposed to bulk Ag contained 1170 ng/g chlordane, but levels in the NP-exposed earthworms were 279 ng/g. At the 500 mg/kg exposure, the smallest coated NPs exerted the greatest suppression in chlordane accumulation; at the 2 higher concentrations, chlordane uptake was unaffected by NP size or coating. The findings show that in exposed earthworms Ag particle size does significantly impact accumulation of the element itself, as well as that of coexisting weathered pesticides. The implications of these findings with regard to NP exposure and risk are unknown but are the topic of current investigation. Environ Toxicol Chem 2017;36:1864-1871. © 2016 SETAC.

Anxiety Curing Evaluation with the Aqueous Extract of <i>Securidaca longepedunculata </i>(<i>Polygalaceae</i>) <i>Decoction</i> in Mice on the Stress Paradigm Tests

“…The results obtained in the open field test showed a significant increase of the number of crossings, the time spent in the centre of mice treated with S. longepedunculata extract. So, these parameters indicate the increase of locomotor activity and the level of exploration in rodents, this is an intrinsic manifestation of the reduction of anxiety [17,18]. Our results suggest that the decoction of S. longepedunculata could contain compounds that possess anxiolytic properties.…”

“…These results suggest that the plant extract like the diazepam would have anxiolytics properties. This aqueous extract would act through to the complex GAbA-A receptor at the level of barbiturates receptor sites, benzodiazepine, alcohol, thiroidian or gaba sites too, by extending the opening of voltage-dependent chloride channel to produce the anxiolytic effect [16,17]. The results obtained in the open field test showed a significant increase of the number of crossings, the time spent in the centre of mice treated with S. longepedunculata extract.…”

A critical review of the environmental impacts of manufactured nano-objects on earthworm species

“…Toxicity in general is dependent on several factors, including particle size, exposure concentration and duration, experimental conditions and Ag-NPs properties, such as surface stabilization or coating, surface speciation, shape etc. (Bourdineaud et al, 2019;Mukherjee et al, 2017). A consistent finding was that the toxicity of AgNPs increased with decreasing size of the NPs; this is likely due to the higher surface to volume ratio of smaller NPs that results in both faster dissolution and likely greater uptake of discrete particles (Hu et al, 2012).…”