Ecogenotoxicity Measurements of Nanoparticles

Summary

As a result of their novel properties, nanoparticles are expected to be produced and incorporated into consumer products at exponentially increasing quantities. However, the potential risks they may pose during production, during use of the consumer goods, or after disposal are largely unknown. One particularly important toxicological endpoint is genotoxicity, given that oxidatively induced DNA damage can cause mutations, cancer and premature aging.

Description

Intended Impact
Understanding the potential environmental fate of NPs has direct implications to the US economy, as potential environmental and human health impacts of NPs is one of the main factors slowing the commercialization of this technology. Reducing the uncertainty regarding the environmental fate and risks of NPs will facilitate sustainable commercialization of products utilizing NPs. The results from this project are expected to also help other government agencies such as EPA and FDA with a robust and scientifically grounded risk assessment of NPs.

Objective
The objectives of this project are to develop transferable methods to accurately assess the genotoxic effects of various NPs on ecological receptors using mass spectrometry based techniques and develop a mechanistic understanding of DNA damage by investigating the patterns of oxidatively induced DNA lesions.

Goals

1. Measure the extent to which various nanoparticles (i.e., copper oxide NPs and titanium oxide NPs) can cause oxidatively induced DNA damage to plants.
2. Develop methods for assessing the genotoxicity of nanoparticles with various ecological receptors (i.e., earthworms, fish, clams).

Research Activities and Technical Approach
Plants will be exposed to NPs, macro particles, and dissolved ions in hydroponic (i.e., water-only) conditions for a predetermined time period. DNA will then be extracted and analyzed using gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/tandem mass spectrometry (LC-MS/MS) with isotope-dilution to measure DNA base lesions such as 2,4-diamino-5-formamidopyrimidine, 2,6-diamino-4-hydroxy-5-formamidopyrimidine, 8-hydroxyguanine, and (5'R)- and (5'S)-cyclo-2'-deoxyadenosines. The patterns of DNA damage will be observed and analyzed for mechanistic understanding.

Major Accomplishments

• CuO NPs, bulk particles, and ions were found to cause oxidatively induced DNA damage in model ryegrass and radish plant species.
• These effects varied among the plant species indicating that there are significant species-specific capacities of plants to resist oxidatively induced DNA damage.