Rare earth (REE) and platinum group (PGE) elements are widely applied geochemical techniques in the geological sciences. These trace elements are commonly used to evalaute provenance, meteorite impacts, water-rock interactions, mineral precipiation reactions, and melt crystalization, among other applications. Nonetheless, many of these trace element proxies, specifically rare earth elements, are seldom used as natural tracers of mineral interactions in the medical or biological sciences and only recently considered in environmental assessments. <p">Within the last decade, there has been an increasing awareness and number of applications for REE and PGE geochemistry in the medicinal and environmental sciences. The increased awareness of REE and PGE geochemistry has largely stemmed from the dramatic increase in the medicinal (e.g., contrast enhancemenet agents, chemotherapeutics) and industrial (e.g., nanotechnology, electronics) usage of these metals in the last few decaes. These applications have lead to an increased potential for exposure to toxic REE and PGE in the workplace and the environment. More recently, the geochemical applications of these parameters have been used to evaluate in vivobio-inorganic reactions that are similar to geological minerlization (e.g., hydroxyapatite precipitation).

Here, I will provide a summary of the available geochemical data on REE and PGE in the environment and in the human body. We will examine environmetnal samples including municipal water supplies, sediment cores, and air, as well as human sample types including bone, blood, hair, and placenta of modern humans. The presentation will include a comparison of how the environmental levels of these elements have changed over time and how trace element geochemistry of humans have changed throughout the last 150 years using archaeological, historical, and modern human specimens. While humans have alwasy been effected by the geochemistry of their environment, the current data set shows that types of elements and their levels of exposure have changed rapidly with time.