Quantum dots exhibit less bioaccumulation than free cadmium and selenium in the earthworm Eisenia andrei
This work addresses the bioaccumulation behavior of cadmium selenide quantum dots (QD) by Eisenia andrei earthworms in a terrestrial environment. Earthworms were exposed to QD‐treated soil for up to four weeks, and analyzed for cadmium and selenium concentration using inductively coupled plasma mass spectrometry. Results were compared to earthworms exposed to cadmium nitrate and selenious acid, as positive controls, and those exposed in un‐treated soil (negative control). Earthworms exposed to QD showed significant bioaccumulation of cadmium and selenium (5.3 and 1.5 fold higher concentration over negative controls, respectively) after four weeks. Over the same four weeks, positive control earthworms accumulated 9.2 and 2.2 fold higher cadmium and selenium than negative controls for a much more substantial final body burden of the two elements. The concentrations also increased with exposure time; cadmium concentrations increased from 3600±310 ng/g to 8080±660 ng/g, from one to four weeks, suggesting further bioaccumulation may take place with even longer exposure time. The molar ratio of cadmium to selenium in the QD exposed worms (6.2) is closer to the ratios seen in positive control worms (7.2) than to the pure QD (1.8), which implies that QD are taken up predominately in the degraded form. Results from this study suggest that chemical modification of QD to protect them from environmental degradation could potentially reduce bioaccumulation of the nanoparticles by earthworms. Environ. Toxicol. Chem. © 2013 SETAC
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