Citation:

Kitchin, K., J. Richards, B. Robinette, K. Wallace, N. Coates, AND B. Castellon. Biochemical effects of six TiO2 and four CeO2 nanomaterials in HepG2 cells. Society of Toxicology, San Diego, CA, March 22 - 27, 2015.

Impact/Purpose:

To be presented at the annual SOT Meeting, March, 2015

Description:

Biochemical effects of six TiO2 and four CeO2 nanomaterials in HepG2 cellsBecause of their growing number of uses, nanoparticles composed of CeO2 (cosmetics, polishing materials and automotive fuel additives) and TiO2 (pigments, sunscreens and photocatalysts) are of particular toxicological interest. In dose-response and structure-activity studies, human hepatic HepG2 cells were exposed in vitro to between 10 and 1000 ug/ml of six different TiO2 and four CeO2 nanomaterials for 3 days. Various biochemical parameters were then evaluated to study cytotoxicity, cell growth, hepatic function and oxidative stress. Few indications of cytotoxicity were observed between 10 and 100 ug/ml. But between 300 to 1000 ug/ml a moderate to substantial degree of cytotoxicity was observed. The four major biochemical effects observed were decreased activities of glucose 6-phosphate dehydrogenase (G6PDH), superoxide dismutase, glutathione reductase and glutathione peroxidase. The two largest contributors to hepatic oxidative stress may be (a) GSH depletion (~80%) by free radical attack generated by the nanomaterials and (b) inhibition of G6PDH (~30% decrease) which will decrease the concentration of NADPH and the effectiveness of the GPX enzyme (~20% decrease observed). Nanomaterials with 99.9% chemical identity can be surprisingly different in their biological effects. Disclaimer: [This is an abstract or a proposed presentation and does not necessarily reflect EPA policy. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.]

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