Can a single strand of hair be used to monitor exposure to toxic metals?

Hair is a growing keratinous tissue comprised of sulfur. As such, the sulfur in the hair can bind the many elements present in circulating blood, including toxic metals. Since hair is metabolically inert once formed, the elements retained in the tissue become locked in, so as the hair grows it can record changes in blood element concentrations over time. Using laser ablation on single strands of hair, exposure histories can be revealed for toxic metals. But, there are some caveats, including external contamination by air, water, and hair treatments. Here we will discuss occupational exposure to lead and other metals, compare hair and blood concentrations, effects of contamination on hair concentrations, examine another growing keratinous tissue (nails) for metal monitoring, and provide forensic case studies from an inadvertent poisoning event, and the historic Franklin Expedition.