Non-dietary ingestion

Route of exposure is defined as the portal of entry to the body. Pathway is defined as the course that the contaminant takes from its source to the exposure medium, and then to the portal of entry. For a given source, exposure media and exposure routes can define the pathways. Depending upon the life stage of the child, exposure media can include amniotic fluid, breast milk, air, water, soil/dust/ sediments, food, and objects/surfaces. Exposure routes include transplacental transfer, inhalation, ingestion, dermal absorption, and indirect (non-dietary) ingestion. 

Hubal, C.E., K. Thomas, J. Quackenboss, E. Furtaw, and L. Sheldon (1999). Dermal and Non-Dietary Ingestion Workshop, EPA 600/R-99/039, United States Environmental Protection Agency, Research Triangle Park, NC, USA. 

Abstract Indoor contamination is one source of exposure to toxic pollutants and has been classified as a high environmental risk. Epidemiological research linked health effects including childhood leukemia and neuroblastoma to the indoor occurrence of pesticides. Pesticides in indoor environments contribute to human exposure via inhalation, non dietary ingestion and dermal contact. Sources for pesticides indoors are direct applications, pesticides used in varnishes, colors, adhesives, etc., or in finishing textiles, leather, carpets, etc., and pesticides brought in from outdoors. Results for pesticides in indoor environments from different countries and obtained under different conditions are compiled in this chapter. They are discussed by applying two approaches (1) the comparison with reference values... 

Indirect ingestion (dietary and non-dietary) exposure (Ejngmj) Ejngmi = Csurfx x TEx x SAx x EF ... 

The concept of bioavailability was developed to explain the difference between the total amount of mineral in a food and the amount which was used by the individual consuming the food. Over the past sixty years or more, there have been numerous studies related to dietary calcium requirements and bioavailability (1,2). As a result, much is known about non-calcium food components which influence the absorption and utilization of dietary calcium under experimental conditions. What now is lacking is a detailed knowledge of how these factors interact with calcium under normal conditions of ingestion in meals. 

The explanation of why almost all non-essential heavy metals are toxic, and thereby contrast sharply with the non-toxicity of essential iron, copper, and zinc is biological, not chemical. When the evolutionary process selected a heavy metal to carry out one or more essential biological functions it also apparently developed homeostatic mechanisms to rid the organism of inadvertently ingested excesses of the metal (and, incidentally, to conserve the element in times of dietary scarcity). Moreover, evolution was also required to reduce the inherent chemical toxicity of the free ions of an essential metal by providing a protective macro-molecular structure (usually a protein) that would envelop the metal and permit it to play the physiologic role for which it was selected while reducing its thermodynamic activity to zero. 

---