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157782 
Journal Article 
Comparative toxicity of nano-scale TiO2, SiO2 and ZnO water suspensions 
Adams, LK; Lyon, DY; Mcintosh, A; Alvarez, PJ 
2006 
1 
Water Science and Technology
ISSN: 0273-1223
EISSN: 1996-9732 
54 
11-12 
327-334 
English 
17302336 
has comment/response 157524 [Personal communication to Amy Wang regarding information of TiO2 used in a 2006 study (Adams et al., 2006)]
TiO2, SiO2 and ZnO are common additives with improved applications at the nanoscale. The antibacterial activity of TiO2, which has important ecosystem health implications, is well understood. However, less attention has been paid to the antibacterial activity of SiO2 and ZnO despite them also producing reactive oxygen species. This paper explores the relative toxicity of TiO2, SiO2 and ZnO water suspensions towards bacteria (B. subtilis, E. coli) and the eukaryotic Daphnia magna. These three photosensitive nanomaterials were hazardous to all test organisms, with toxicity increasing with particle concentration. Toxicity of the three compounds decreased from ZnO to TiO2 to SiO2 and Daphnia were most susceptible to their effects. Nominal particle size did not affect the toxicity of these compounds. Antibacterial activity was noted under both dark and light conditions indicating that mechanisms additional to ROS production were responsible for growth inhibition. These results highlight the need for caution during the use and disposal of such manufactured nanomaterials to prevent unintended environmental impacts, as well as the importance of further research on the mechanisms and factors that increase toxicity to enhance risk management.