to have the highest priority. In compiling these recommendations the committee required that the research proposed must involve collaboration between researchers from both the earth science and the public health communities and did not consider the abundant examples of valuable research that could be undertaken primarily within one or other of the disciplines.

Assessment of human exposure to hazards in the environment is often the weakest link in most human health risk assessments. The physical, chemical, and biological processes that create, modify, or alter the transport and bioavailability of natural or anthropogenically generated earth materials remain difficult to quantify, and a vastly improved understanding of the spatial and geochemical attributes of potentially deleterious earth materials is a critical requirement for effective and efficient mitigation of the risk posed by such materials. An improved understanding of the source, fate, rate and transport, and bioavailability of potentially hazardous earth materials is an important research priority. Collaborative research should include:

• Addressing the range of issues associated with airborne mixtures of pathogens and physical and chemical irritants. The anticipation and prevention of health effects caused by earth-sourced air pollution prior to the onset of illness requires quantitative knowledge of the geospatial context of earth materials and related disease vectors.

• Determining the influence of biogeochemical cycling of trace elements in water and soils as it relates to low-dose chronic exposure via toxic elements in foods and ultimately its influence on human health.

• Determining the distribution, survival, and transfer of plant and human pathogens through soil with respect to the geological framework.

• Improving our understanding of the relationship between disease and both metal speciation and metal-metal interaction.

• Identifying and quantifying the health risks posed by “emerging” contaminants, including newly discovered pathogens and pharmaceutical chemicals that are transported by earth processes.

Natural earth processes—including earthquakes, landslides, tsunamis, and volcanoes—continue to cause numerous deaths and immense suffering worldwide. As climates change, the nature and distribution of