Sources Of Exposure Error In Particulate Matter Epidemiology And Risk Assessment
On this page:
Exposure is defined here as the amount of a substance that comes into contact with an absorbing surface during a specified period of time. The normal units of exposure are expressed as micrograms per day. The two components of exposure are the concentration of the substance in the medium, such as ingested food or dust, and the amount of the medium that is ingested per day. Thus, if dust has a concentration of 2000 micrograms of Pb per gram and 100 milligrams (0.1 g) of dust are ingested per day, then the exposure would be 200 micrograms Pb per day from this source.
In some ways, the routes of exposure for lead are the same as for nutrient methal such as calcium: food and drinking water. In this sense, lead is similar to calcium in the way the metal is ingested, absorbed into the body, and distributed among the various body tissues and organs. A substantial amount of lead is also ingested with soil and dust, and some is inhaled with air. In natural circumstances, lead is found in biogeochemical reservoirs similar to naturally occurring nutrient metals, and moves between reservoirs along natural pathways in the same manner as nutrient metals. In many ways, human exposure to lead is subject to the same natural processes that control the movement of nutrient metals such as calcium.
In some ways, the routes of exposure for lead are the same as for nutrient methal such as calcium: food and drinking water. In this sense, lead is similar to calcium in the way the metal is ingested, absorbed into the body, and distributed among the various body tissues and organs. A substantial amount of lead is also ingested with soil and dust, and some is inhaled with air. In natural circumstances, lead is found in biogeochemical reservoirs similar to naturally occurring nutrient metals, and moves between reservoirs along natural pathways in the same manner as nutrient metals. In many ways, human exposure to lead is subject to the same natural processes that control the movement of nutrient metals such as calcium.