Emerging contaminants and public health: Evaluation of the stability, toxicity, and treatment of engineered nanoparticles in drinking water

• Main Author: Abbott Chalew, Talia E
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01.01.2012
• Subjects: Contamination; Drinking water; Nanoparticles; Public health; Toxicity
• ISBN: 9781267770608; 1267770600

Engineered nanoparticles (NPs) are widely used in consumer products, which may release NPs into the domestic waste stream during use and disposal, leading to NPs in the aquatic environment with potential adverse impacts on humans and aquatic organisms. My doctoral research explored NP fate and transport in the aquatic environment and focused on NP ingestion via drinking water and human health effects. This research characterized commercially available silver (Ag), zinc oxide (ZnO), and titanium dioxide (Ti02) NPs, investigated the stability of NPs in synthetic waters, natural waters, and wastewaters, and assessed toxicity to human intestinal epithelial cells. NPs were characterized directly from the manufacturer and after seeding into ultra-pure and test waters. NP characteristics differed from manufacturer specifications and by suspension media, confirming the need to thoroughly characterize NPs in all experimental exposures and time frames. NP aggregation and sedimentation was monitored with dynamic light scattering and ultraviolet-visible light spectroscopy. In some waters, it was observed that natural organic matter (NOM) stabilized NPs so they remained suspended in the water, leading to greater likelihood of human exposure. Removal of NPs from synthetic and natural waters was investigated through simulated conventional drinking water treatment (coagulation/flocculation/sedimentation) and advanced treatment (membrane filtration). Overall, membrane filtration was most effective at removing NPs, based on inductively coupled plasma — mass spectrometry measurements. Despite high NP removal from both conventional and advanced treatment, NPs were still detected in finished waters. Human intestinal epithelial Caco-2 and SW480 cells were exposed to 0-100 ppm NPs in cell culture media and buffered synthetic freshwaters with subsequent measurements of cell viability and cell stress. It was observed that100 ppm Ag NPs and 10-100 ppm ZnO NPs caused significant cell death but no cell death occurred following TiO2 NP exposures. NP exposures also led to increased reactive oxygen species and pro-inflammatory cytokine IL-8 generation. Overall, I determined that NPs could be stabilized in natural and wastewaters and remain in finished waters even after drinking water treatment. Therefore, exposure to NPs via ingestion is a significant possibility and thus it is critical to understand the effects of ingested nanoparticles in an effort to protect human health.