To determine if nanoparticles (NPs) could be transferred from soil media to invertebrates and then to secondary consumers, we examined the trophic transfer of Au NPs along a simulated terrestrial food chain. Earthworms (Eisenia fetida) were exposed to Au NPs in artificial soil media and fed to juvenile bullfrogs (Rana catesbeina). Earthworm Au concentrations were continuously monitored so that the cumulative dose to bullfrogs could be accurately estimated throughout the experiment. We exposed a second group of bullfrogs to equivalent doses of Au NPs by oral gavage to compare the bioavailability of NPs through direct exposure to trophic exposure. We observed accumulation of Au in liver, kidney, spleen, muscle, stomach, and intestine in both treatment groups. Tissue concentrations decreased on average of approximately 100-fold with each trophic-step. The total assimilated dose averaged only 0.09% of the administered dose for direct exposure (oral gavage), but 0.12% for the trophic exposure. The results suggest that manufactured NPs present in soil may be taken up into food chains and transferred to higher order consumers. They also suggest that Au NPs may be more bioavailable through trophic exposure than direct exposure and that trophic transfer may influence the biodistribution of particles once absorbed.

Silver nanoparticles have been incorporated into a wide variety of consumer products, ideally acting as antimicrobial agents. Silver exposure has long been known to cause toxic effects to a wide variety of organisms, making large scale production of silver nanoparticles a potential hazard to environmental systems. Here we describe the first evidence that an organism may be able to sense manufactured nanoparticles in a complex, environmentally relevant exposure and that the presence of nanoparticles alters the organism's behavior. We found that earthworms (Eisenia fetida) consistently avoid soils containing silver nanoparticles and AgNO(3) at similar concentrations of Ag. However, avoidance of silver nanoparticles occurred over 48 h, while avoidance of AgNO(3) was immediate. It was determined that avoidance of silver nanoparticles could not be explained by release of silver ions or any changes in microbial communities caused by the introduction of Ag. This leads us to conclude that the earthworms were in some way sensing the presence of nanoparticles over the course of a 48 h exposure and choosing to avoid exposure to them. Our results demonstrate that nanoparticle interactions with organisms may be unpredictable and that these interactions may result in ecologically significant effects on behavior at environmentally relevant concentrations.

Soft tissue infections requiring incision and drainage are common in the pediatric population, with the majority caused by methicillin-resistant Staphylococcus aureus. Infections requiring drainage most frequently occurred in the diaper area of girls younger than 3 years old. Changing to an MI technique significantly decreased the hospital costs and LOS in our patient population.

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