engleski

Are rare earth elements safe for use in zootechny?; trophic transfer and effects of lanthanide nanoparticles in a simple food web

Rare earth elements have become a major topic of interest due to their potentially beneficial effects as feed additives in zootechny. For example, the European Food Safety Agency has recently suggested that such use of lanthanides in specific farm animals does not represent a cause for concern in terms of toxicity profile. In contrast, recent evidence suggesting that lanthanides, especially in fine particulate form, may give rise to deleterious effects in a range of organisms indicates more caution is warranted. It is in the context of such conflicting information that we report on lanthanide nanoparticles in an aquatic food web in terms of uptake, bioaccumulation, toxicity and biomagnification. Lanthanum fluoride nanoparticles (25 nm diameter) were synthesised and their impact on growth and photosynthesis in alga Dunaliella biocculata (concentration range 1-10 mg L-1) was determined. While significant effects were not recorded, clear sequestration of the nanoparticles by the micro- algae indicated a potential route to trophic transfer, thus uptake of nanoparticle-treated algae by mussel Mytilus galloprovincialis was investigated. Mussels were exposed to nanoparticle (2 mg L-1) -loaded algae for 24 h and accumulation of nanoparticles was detected in hemolymph, gills and hepatopancreas. It was noted that the uptake of nanoparticles was significantly greater in the presence of algae than for nanoparticles on their own. A significant reduction in mussel total haemocyte count, and accumulation in gills (25 μg g-1) and hepatopancreas (50 μg g-1), was noted after nanoparticle treatment. Depuration of the nanoparticles from the mussels was tracked and over 96 h lanthanide concentrations in the pseudofaeces returned to near background levels. Ultimately, these data indicate that trophic transfer is an efficient route to bioaccumulation and potentially biomagnification of lanthanide nanoparticles and indicates that broader toxicity testing be carried out in a range of non-target organisms when lanthanides are used in zootechny.

animal feed ; nanoparticle ; lanthanides ; enzymatic activity

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