title: Bioaccumulation of Multiwall Carbon Nanotubes in Tetrahymena thermophila by Direct Feeding or Trophic Transfer.
abstract: Consumer goods contain multiwall carbon nanotubes (MWCNTs) that could be released during product life cycles into the environment, where their effects are uncertain. Here, we assessed MWCNT bioaccumulation in the protozoan Tetrahymena thermophila via trophic transfer from bacterial prey (Pseudomonas aeruginosa) versus direct uptake from growth media. The experiments were conducted using (14)C-labeled MWCNT ((14)C-MWCNT) doses at or below 1 mg/L, which proved subtoxic since there were no adverse effects on the growth of the test organisms. A novel contribution of this study was the demonstration of the ability to quantify MWCNT bioaccumulation at low (sub μg/kg) concentrations accomplished by employing accelerator mass spectrometry (AMS). After the treatments with MWCNTs at nominal concentrations of 0.01 mg/L and 1 mg/L, P. aeruginosa adsorbed considerable amounts of MWCNTs: (0.18 ± 0.04) μg/mg and (21.9 ± 4.2) μg/mg bacterial dry mass, respectively. At the administered MWCNT dose of 0.3 mg/L, T. thermophila accumulated up to (0.86 ± 0.3) μg/mg and (3.4 ± 1.1) μg/mg dry mass by trophic transfer and direct uptake, respectively. Although MWCNTs did not biomagnify in the microbial food chain, MWCNTs bioaccumulated in the protozoan populations regardless of the feeding regime, which could make MWCNTs bioavailable for organisms at higher trophic levels.
authors.affiliation: Bren School of Environmental Science and Management, Earth Research Institute and University of California Center for the Environmental Implications of Nanotechnology (UC CEIN), University of California , Santa Barbara, California 93106, United States.|Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics , Akadeemia tee 23, Tallinn 12618, Estonia.
authors.forename: Monika
authors.initials: M
authors.lastname: Mortimer
authors.affiliation: Biosystems and Biomaterials Division, Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
authors.forename: Elijah J
authors.initials: EJ
authors.lastname: Petersen
authors.affiliation: Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory , Livermore, California 94550, United States.
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Buchholz
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of California , Santa Barbara, California 93106, United States.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Orias
authors.affiliation: Bren School of Environmental Science and Management, Earth Research Institute and University of California Center for the Environmental Implications of Nanotechnology (UC CEIN), University of California , Santa Barbara, California 93106, United States.
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Holden
mesh_terms: D020387:Food Chain; D037742:Nanotubes, Carbon / Q000737:chemistry*; D011550:Pseudomonas aeruginosa; D016808:Tetrahymena thermophila
chemical_list: D037742:Nanotubes, Carbon