Laser Ablation Mass Spectrometry Analyzing Heavy Metal Concentration in Teeth

Objective: This is a pilot study to test the feasibility of using Laser Ablation Mass Spectrometry in analyzing heavy metal concentrations within a tooth. Lead and Mercury in particular are known to have deleterious effects on cognitive development. The long-term objective is to employ this method in using heavy metal deposition in teeth as a longitudinal and historical biomarker for environmental contaminants. By analyzing concentrations of heavy metals within a tooth from enamel to dentin, the goal is to trace an individual’s exposure to these contaminants over time as heavy metals are incorporated into hydroxyapatite during tooth calcification.

Method: Five human or animal teeth from the US or China, one each of human, skunk and raccoon from New England, and one each of human and pig teeth from China, were longitudinally sectioned using an Isomet diamond saw.  Laser ablation (Merchantek Research UP213) coupled with ICPMS (ThermoFinnigan Element 2) was used to analyze the concentration ratio of Hg, Cd, Sr and Pb 206, 207, 208 to Ca along the cut surface of each tooth from enamel to dentin in a continuous line of 55 microns width.

Results: The concentrations of heavy metals were reported in proportion to calcium.

ave. heavy metal ratio	tooth
	human-China	pig-China	human-US	raccoon-US	skunk-US
Cd/Ca	0.0502	0.0014	0.0017	0.0566	0.0058
Hg/Ca	0.0099	0.0003	0.0128	0.0106	0.0011
Pb206/Ca	0.0074	0.0003	0.0005	0.0376	0.0149
Pb207/Ca	0.0068	0.0003	0.0004	0.0309	0.0127
Pb208/Ca	0.0143	0.0007	0.0011	0.0751	0.0308
Sr/Ca	0.2712	0.1301	0.1545	0.5634	0.1974

Conclusion:  These initial findings show differences in heavy metal concentrations of teeth in individuals of different species and geographic locations. This methodology appears useful in evaluating heavy metal deposition in teeth as a biomarker for environmental contaminants.