EPA Science Inventory

Phototoxicity of TiO2 Nanoparticles under Solar Radiation to Two Aquatic Species: Daphnia magna and Japanese Medaka

Citation:

MA, H., A. BRENNAN, AND S. A. DIAMOND. Phototoxicity of TiO2 Nanoparticles under Solar Radiation to Two Aquatic Species: Daphnia magna and Japanese Medaka. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY. Society of Environmental Toxicology and Chemistry, Pensacola, FL, 31(7):1621-1629, (2012).

Description:

One target of development and application of TiO2 nanoparticles (nano-TiO2) is photochemical degredation of contaminants and photo-killing of microbes and fouling organisms. However, few ecotoxicological studies have focused on this aspect of nano-TiO2, specifically whether this photoreactivity might significantly increase hazard and risk of the materials in the natural environment. In this study, we evaluated acute phototoxicity of nano-TiO2 under simulated solar radiation (SSR) to two aquatic species - Daphnia magna and Japanese Medaka, using 48-h and 96-h assays, respectively. A thorough characterization of the exposure system was performed by measuring particle agglomerationand TiO2 concentration in suspension in a time-course manner. Sedimentation and loss of bulk concentration of nano-TiO2 particles occurred at all concentrations above 2 mg/L and was more significant as concentration increased. Phototoxicity of nano-TiO2 under SSR was enhanced by two to four orders of magnitude as compared to toxicity under ambient laboratory light, with a 48-h LC50 of 29.8 µg/L in D. magna and a 96-h LC50 of 2.2 mg/L in Medaka. Our results also indicate that these effects are dependent on simultaneous exposure of the organisms to nanoparticles and SSR. This dramatic increase in toxicity of nano-TiO2 at environmentally-realistic levels of SSR indicates the need for incorporating this mode of action into risk assessment for nano-TiO2 and other photoreactive nanomaterials.

Purpose/Objective:

To document research results.

Record Details:

Record Type: DOCUMENT (JOURNAL/PEER REVIEWED JOURNAL)
Start Date: 07/01/2012
Completion Date: 07/01/2012
Record Last Revised: 10/29/2012
Record Created: 12/23/2011
Record Released: 12/23/2011
OMB Category: Other
Record ID: 240206

Organization:

U.S. ENVIRONMENTAL PROTECTION AGENCY

OFFICE OF RESEARCH AND DEVELOPMENT

NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LAB

MID-CONTINENT ECOLOGY DIVISION

ECOLOGICAL TOXICOLOGY RESEARCH BRANCH