(interindividual variability), the uncertainty in extrapolating animal data to the human population (interspecies uncertainty), the uncertainty in extrapolating from data obtained in a study involving less-than-lifetime exposure (extrapolating from subchronic to chronic exposure), the uncertainty in using LOAEL data rather than NOAEL data, and the uncertainty associated with extrapolation when the database is incomplete.16 A UF of 10 is considered to be a health-protective default value to be used when little is known about a particular source of variability or uncertainty or when information on a relevant health effect is lacking. As additional research becomes available, UFs change as indicated by the new information.


VGI:

volume of gastrointestinal tract.

Vmax:

describes, in units of milligrams per hour, the maximal capacity or velocity for binding or transport, such as binding or transport of iodide by the NIS.

VmaxC:

describes, in units of milligrams per hour per kilogram of body weight, the maximal capacity or velocity for binding or transport scaled by body weight according to the equation: Vmax (mg/hr) = [VmaxC (mg/hr per kg)][body weight (kg)]0.70.

VSk:

volume of skin.

NOTES

1.  

EPA (U.S. Environmental Protection Agency). 2003. Glossary of IRIS Terms. Integrated Risk Information System (IRIS). [Online]. Available http://www.epa.gov/iris/gloss8.htm [accessed April 16, 2004].

2.  

CanSIS (Canadian Soil Information System). 1996. Glossary: Caliche. Canadian Soil Information System, Canada Department of Agriculture, Ottawa. [Online]. Available: http://sis.agr.gc.ca/cansis/glossary/index.html [accessed April 16, 2004].

3.  

Colton, T. 1974. Statistics in Medicine, 1st Ed. Boston: Little, Brown and Company.

4.  

Stedman, T.L. 2000. Stedman’s Medical Dictionary, 27th Edition. Philadelphia: Lippincott Williams and Wilkins.

5.  

Rosner, B. 1995. Pp. 23-24 in Fundamentals of Biostatistics. Belmont, CA: Duxbury Press.

6.  

Altman, D.G. 1991. Practical Statistics for Medical Research. London: Chapman and Hall.

7.  

IOM (Institute of Medicine). 2000. Iodine. Pp 258-289 in Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press.



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