Indexed on: 26 Aug '10Published on: 26 Aug '10Published in: Nanomedicine (London, England)
Double-walled carbon nanotubes (DWNTs) are found in a variety of consumer products, but there are no ecotoxicity data of DWNTs into marine organisms.Chronic toxicity of DWNTs was investigated with the diatom Thalassiosira pseudonana, copepod Tigriopus japonicus and medaka Oryzias melastigma. DWNTs were dispersed using sonication (so-DWNTs) and stirring (st-DWNTs) for comparison.The median aggregation size (0.89 microm(2)) of so-DWNTs was smaller than that of st-DWNTs (21.8 microm(2)). Exposure to DWNTs led to growth inhibition of T. pseudonana with EC(50)s of 1.86 and 22.7 mg/l for so- and st-DWNTs, respectively. Population growth of T. japonicus was reduced to 0.1 mg/l for so-DWNTs and 10 mg/l for st-DWNTs. Growth inhibition in O. melastigma was observed at 10 mg/l for so-DWNTs but not for st-DWNTs.Given that so-DWNTs are consistently significantly more toxic than st-DWNTs, dispersion method and size of aggregations should be considered in DWNT toxicity testing.