Brianne Duncan

Project title: Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) as a biomonitoring tool

Degree: PhD | Program: Environmental and Occupational Hygiene (EOHY) | Project type: Thesis/Dissertation
Completed in: 2019 | Faculty advisor: Christopher D. Simpson


Using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), this research analyzed human cadaver hair for gadolinium and mice hair samples for cadmium. This project combined fundamental bench science (analytical chemistry and animal studies), and insight into exposures to an emerging contaminant. This study demonstrated the feasibility of LA-ICP-MS to measure time resolved exposure profiles in hair samples, potentially opening up a transformative new exposure analysis method for investigators conducting both bench toxicology and human epidemiology studies. Consecutive autopsy cases that presented at the University of Washington’s medical department, who had received a gadolinium-based contrasting agent (GBCA) to enhance magnetic resonance imaging procedures constituted the human population component of this research. Multiple hairs from numerous subjects were analyzed using LA-ICP-MS along with calibration gels (bovine-skin based) and a standard reference material glass disc with trace metals. Overall analytical method accuracy and precision was acceptable. There was moderate correlation between gadolinium dose and area under the curve as well as gadolinium peak position and GBCA injection day. Hair concentrations were also compared to the other tissue (brain, bone, and skin) concentrations using linear regression. This analysis showed good correlation between hair gadolinium concentrations and brain and skin gadolinium concentrations. These results suggest that hair may serve as a safe and effective biomonitoring tissue for patients who receive GBCA injections. A mouse animal model was used to evaluate LA-ICP-MS as a biomonitoring tool in assessing cadmium exposure. Hair samples from mice that were part of a mechanistic toxicology study at the University of Washington were opportunistically obtained for inclusion in this analytical methods-focused element of the research. The mice were dosed with cadmium-spiked water at three levels (0, 0.6, and 3 mg/L) for 14 weeks before they were sacrificed. Hairs from seven mice were analyzed using LA-ICP-MS. This research showed that there were increasing concentrations of cadmium in hair shafts with increasing doses of cadmium in drinking water among mice. URI