parameter space such that the probability that the parameter’s value lies in the interval is at least the given percentage.


coefficient of variation. A metric useful in comparing the variability of multiple datasets calculated by dividing the standard deviation of a dataset by its mean.5


enzymes that metabolize thyroid hormones, including conversion of the prohormone thyroxine to triiodothyronine by removal of an iodide.


an intermediate in the production of thyroid hormones. It contains two iodine atoms.4


deciliter. One-tenth of a liter or 100 milliliters.


day of lactation.

ecologic study:

a type of observational epidemiologic study in which the units of analysis are populations or groups of people rather than individuals.


effective dose 10%. The ED10 is the dose associated with a 10% increase in an adverse effect compared with the control.1


gestation day.

geometric mean:

the nth root of the product of n observations.5 The geometric mean is similar to the median and always less than the arithmetic mean unless the observations are identical, making the geometric mean equal to the arithmetic mean.6


a chronic enlargement of the thyroid gland, not due to a neoplasm.4


any substance that induces goiter.4


human equivalent exposure.


see hypothalamic-pituitary-thyroid axis.


an increase in the number of normal cells in a tissue or organ, excluding tumor formation, whereby the bulk of the part or organ may be increased.4


increased secretion of thyroxine and triiodothyronine from the thyroid gland.


general increase in bulk of a part of organ, not due to tumor formation.4

Hypothalamic-pituitary-thyroid axis:

the body’s regulatory system for the thyroid. Thyrotropin-releasing hormone from the hypothalamus stimulates the pituitary gland to secrete thyroid-stimulating hormone, which acts on the thyroid gland to stimulate thyroid hormone synthesis and secretion. High concentrations of thyroid hormone in the blood feed back to the hypothalamus and pituitary and inhibit thyroid-stimulating hormone secretion.4

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement