NEW CONCEPTS IN EXPOSURE AND DOSE ASSESSMENT FOR PRACTICAL MEDICAL GEOLOGY

Exposure and dose assessment is the key interface between geology and human health. The National Academies of Science, Engineering and Medicine (2017) defined “exposure” broadly as the “contact between a stressor and a receptor at any level of biological organization (organism, organ, tissue, or cell)”. A framework that describes a linear path from introduction of a ‘stressor’ into the environment to the exposure-epidemiology interface and the exposure -toxicology interface is central to applications of Medical Geology in risk assessment, regulatory compliance and basic research.

The concentration relationship between contaminant release and an exposure medium such as air, water or soil is determined by its geoavailability. The exposure- epidemiology interface occurs where environmental presence of contaminants leads to external exposure and is affected by both physical and geochemical processes as well the activity patterns of the population. The exposure -toxicology interface occurs where external exposure leads to internal dose and is controlled by bioaccessibility and bioavailability. Biomarkers of exposure that relate external exposures to internal dose include measurement of metals in bodily fluids and tissues. Biomarkers of effects are used to recognize preclinical manifestations of diseases and include a large number molecular biomarkers as well as changes in cellular function and morphology.

Our understanding of the relationships among external exposure, internal exposure, target exposure and dose have been refined by advances in technology such as GPS and GIS, environmental monitoring, computational exposure assessment, physiologically-based pharmacokinetic (PBPK) modeling, and-omics technology. This presentation introduces new concepts from a variety of geomedical, biomedical and environmental fields that can be used by medical geologists for multidisciplinary studies at the interface between the environment and human health.

National Academies of Sciences, Engineering, and Medicine 2017. Using 21st Century Science to Improve Risk-Related Evaluations. Washington, DC: The National Academies Press. https://doi.org/10.17226/24635