, Bruce A. Buchholz, Eduardo Orias, Patricia Holden
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 with 14C-labeled MWCNT (14C-MWCNT) doses at or below 1 mg/L which proved subtoxic to both bacteria and protozoans, manifesting no adverse effects on the growth or feeding patterns of the test organisms. The bioaccumulation of 14C-MWCNTs at environmentally relevant MWCNT concentrations was quantified by newly employing accelerator mass spectrometry (AMS). After the treatments with MWCNTs at nominal concentrations of 0.01 and 1 mg/L, P. aeruginosa adsorbed considerable amounts of MWCNTs: 0.18±0.04 and 21.9±4.2 µg/mg bacterial dry weight, respectively. At the administered MWCNT dose of 0.3 mg/L, T. thermophila accumulated up to 0.86 and 3.4 µg MWCNTs/mg dry weight by trophic transfer and direct uptake, respectively. MWCNTs bioaccumulated in the protozoan populations, regardless of the feeding regime, which could make MWCNTs bioavailable for organisms at higher trophic levels.
Environmental Science & Technology